[RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Thomas Zimmermann]

This patchset adds support for simple-framebuffer platform devices and
a handover mechanism for native drivers to take-over control of the
hardware.

The new driver, called simplekms, binds to a simple-frambuffer platform
device. The kernel's boot code creates such devices for firmware-provided
framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
loader sets up the framebuffers. Description via device tree is also an
option.

Simplekms is small enough to be linked into the kernel. The driver's main
purpose is to provide graphical output during the early phases of the boot
process, before the native DRM drivers are available. Native drivers are
typically loaded from an initrd ram disk. Occationally simplekms can also
serve as interim solution on graphics hardware without native DRM driver.

So far distributions rely on fbdev drivers, such as efifb, vesafb or
simplefb, for early-boot graphical output. However fbdev is deprecated and
the drivers do not provide DRM interfaces for modern userspace.

Patches 1 and 2 prepare the DRM format helpers for simplekms.

Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
pageflips, SHMEM buffers are copied into the framebuffer memory, similar
to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
regulators. It's based on the simplefb drivers, but has been modified for
DRM.

Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
framebuffer's I/O-memory range and provides a callback function to be
removed by a native driver. The native driver will remove simplekms before
taking over the hardware. The removal is integrated into existing helpers,
so drivers use it automatically.

I tested simplekms with x86 EFI and VESA framebuffers, which both work
reliably. The fbdev console and Weston work automatically. Xorg requires
manual configuration of the device. Xorgs current modesetting driver does
not work with both, platform and PCI device, for the same physical
hardware. Once configured, X11 works.

One cosmetical issue is that simplekms's device file is card0 and the
native driver's device file is card1. After simplekms has been kicked out,
only card1 is left. This does not seem to be a practical problem however.

TODO/IDEAS:

	* provide deferred takeover
	* provide bootsplash DRM client
	* make simplekms usable with ARM-EFI fbs

Thomas Zimmermann (9):
  drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()
  drm/format-helper: Add blitter functions
  drm: Add simplekms driver
  drm/simplekms: Add fbdev emulation
  drm/simplekms: Initialize framebuffer data from device-tree node
  drm/simplekms: Acquire clocks from DT device node
  drm/simplekms: Acquire regulators from DT device node
  drm: Add infrastructure for platform devices
  drm/simplekms: Acquire memory aperture for framebuffer

 MAINTAINERS                            |   6 +
 drivers/gpu/drm/Kconfig                |   6 +
 drivers/gpu/drm/Makefile               |   1 +
 drivers/gpu/drm/drm_format_helper.c    |  96 ++-
 drivers/gpu/drm/drm_platform.c         | 118 ++++
 drivers/gpu/drm/mgag200/mgag200_mode.c |   2 +-
 drivers/gpu/drm/tiny/Kconfig           |  17 +
 drivers/gpu/drm/tiny/Makefile          |   1 +
 drivers/gpu/drm/tiny/cirrus.c          |   2 +-
 drivers/gpu/drm/tiny/simplekms.c       | 906 +++++++++++++++++++++++++
 include/drm/drm_fb_helper.h            |  18 +-
 include/drm/drm_format_helper.h        |  10 +-
 include/drm/drm_platform.h             |  42 ++
 13 files changed, 1217 insertions(+), 8 deletions(-)
 create mode 100644 drivers/gpu/drm/drm_platform.c
 create mode 100644 drivers/gpu/drm/tiny/simplekms.c
 create mode 100644 include/drm/drm_platform.h

--
2.27.0

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[PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Thomas Zimmermann]

The memcpy's destination buffer might have a different pitch than the
source. Support different pitches as function argument.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
 drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
 drivers/gpu/drm/tiny/cirrus.c          | 2 +-
 include/drm/drm_format_helper.h        | 2 +-
 4 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index c043ca364c86..8d5a683afea7 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
 /**
  * drm_fb_memcpy_dstclip - Copy clip buffer
  * @dst: Destination buffer (iomem)
+ * @dst_pitch: Number of bytes between two consecutive scanlines within dst
  * @vaddr: Source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
@@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
  * This function applies clipping on dst, i.e. the destination is a
  * full (iomem) framebuffer but only the clip rect content is copied over.
  */
-void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
-			   struct drm_framebuffer *fb,
+void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			   void *vaddr, struct drm_framebuffer *fb,
 			   struct drm_rect *clip)
 {
 	unsigned int cpp = fb->format->cpp[0];
-	unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
+	unsigned int offset = clip_offset(clip, dst_pitch, cpp);
 	size_t len = (clip->x2 - clip->x1) * cpp;
 	unsigned int y, lines = clip->y2 - clip->y1;
 
@@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
 	for (y = 0; y < lines; y++) {
 		memcpy_toio(dst, vaddr, len);
 		vaddr += fb->pitches[0];
-		dst += fb->pitches[0];
+		dst += dst_pitch;
 	}
 }
 EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index f16bd278ab7e..7d4f3a62d885 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
 	if (drm_WARN_ON(dev, !vmap))
 		return; /* BUG: SHMEM BO should always be vmapped */
 
-	drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
+	drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
 
 	drm_gem_shmem_vunmap(fb->obj[0], vmap);
 
diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
index 744a8e337e41..2dd9e5e31e3d 100644
--- a/drivers/gpu/drm/tiny/cirrus.c
+++ b/drivers/gpu/drm/tiny/cirrus.c
@@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 		goto out_dev_exit;
 
 	if (cirrus->cpp == fb->format->cpp[0])
-		drm_fb_memcpy_dstclip(cirrus->vram,
+		drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
 				      vmap, fb, rect);
 
 	else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
index 5f9e37032468..2b5036a5fbe7 100644
--- a/include/drm/drm_format_helper.h
+++ b/include/drm/drm_format_helper.h
@@ -11,7 +11,7 @@ struct drm_rect;
 
 void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
 		   struct drm_rect *clip);
-void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
+void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
 			   struct drm_framebuffer *fb,
 			   struct drm_rect *clip);
 void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
-- 
2.27.0

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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Daniel Vetter]

On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
> The memcpy's destination buffer might have a different pitch than the
> source. Support different pitches as function argument.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

But I do have questions ... why did we allocate a source drm_framebuffer
with mismatching pitch? That sounds backwards, especially for simplekms.

Would be good to add the reasons why we need this to the commit message,
I'm sure I'll discover it later on eventually.
-Daniel

> ---
>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
>  include/drm/drm_format_helper.h        | 2 +-
>  4 files changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> index c043ca364c86..8d5a683afea7 100644
> --- a/drivers/gpu/drm/drm_format_helper.c
> +++ b/drivers/gpu/drm/drm_format_helper.c
> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>  /**
>   * drm_fb_memcpy_dstclip - Copy clip buffer
>   * @dst: Destination buffer (iomem)
> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
>   * @vaddr: Source buffer
>   * @fb: DRM framebuffer
>   * @clip: Clip rectangle area to copy
> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>   * This function applies clipping on dst, i.e. the destination is a
>   * full (iomem) framebuffer but only the clip rect content is copied over.
>   */
> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> -			   struct drm_framebuffer *fb,
> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
> +			   void *vaddr, struct drm_framebuffer *fb,
>  			   struct drm_rect *clip)
>  {
>  	unsigned int cpp = fb->format->cpp[0];
> -	unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
> +	unsigned int offset = clip_offset(clip, dst_pitch, cpp);
>  	size_t len = (clip->x2 - clip->x1) * cpp;
>  	unsigned int y, lines = clip->y2 - clip->y1;
>  
> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>  	for (y = 0; y < lines; y++) {
>  		memcpy_toio(dst, vaddr, len);
>  		vaddr += fb->pitches[0];
> -		dst += fb->pitches[0];
> +		dst += dst_pitch;
>  	}
>  }
>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index f16bd278ab7e..7d4f3a62d885 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
>  	if (drm_WARN_ON(dev, !vmap))
>  		return; /* BUG: SHMEM BO should always be vmapped */
>  
> -	drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
> +	drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
>  
>  	drm_gem_shmem_vunmap(fb->obj[0], vmap);
>  
> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> index 744a8e337e41..2dd9e5e31e3d 100644
> --- a/drivers/gpu/drm/tiny/cirrus.c
> +++ b/drivers/gpu/drm/tiny/cirrus.c
> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
>  		goto out_dev_exit;
>  
>  	if (cirrus->cpp == fb->format->cpp[0])
> -		drm_fb_memcpy_dstclip(cirrus->vram,
> +		drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
>  				      vmap, fb, rect);
>  
>  	else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> index 5f9e37032468..2b5036a5fbe7 100644
> --- a/include/drm/drm_format_helper.h
> +++ b/include/drm/drm_format_helper.h
> @@ -11,7 +11,7 @@ struct drm_rect;
>  
>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
>  		   struct drm_rect *clip);
> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
>  			   struct drm_framebuffer *fb,
>  			   struct drm_rect *clip);
>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
> -- 
> 2.27.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 5216 bytes --]

Hi

Am 29.06.20 um 10:40 schrieb Daniel Vetter:
> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
>> The memcpy's destination buffer might have a different pitch than the
>> source. Support different pitches as function argument.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> 
> But I do have questions ... why did we allocate a source drm_framebuffer
> with mismatching pitch? That sounds backwards, especially for simplekms.

There's userspace that allocates framebuffers in tiles of 64x64 pixels.
I think I've seen this with Gnome. So if you have a 800x600 display
mode, the allocated framebuffer has a scanline pitch of 832 pixels and
the final 32 pixels are ignored.

In regular drivers, we can handle this with the VGA offset register [1]
or some equivalent. That's obviously not an option with simplekms, so
the different pitch is required.

Best regards
Thomas

[1]
https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13

> 
> Would be good to add the reasons why we need this to the commit message,
> I'm sure I'll discover it later on eventually.
> -Daniel
> 
>> ---
>>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
>>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
>>  include/drm/drm_format_helper.h        | 2 +-
>>  4 files changed, 8 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
>> index c043ca364c86..8d5a683afea7 100644
>> --- a/drivers/gpu/drm/drm_format_helper.c
>> +++ b/drivers/gpu/drm/drm_format_helper.c
>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>  /**
>>   * drm_fb_memcpy_dstclip - Copy clip buffer
>>   * @dst: Destination buffer (iomem)
>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
>>   * @vaddr: Source buffer
>>   * @fb: DRM framebuffer
>>   * @clip: Clip rectangle area to copy
>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>   * This function applies clipping on dst, i.e. the destination is a
>>   * full (iomem) framebuffer but only the clip rect content is copied over.
>>   */
>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>> -			   struct drm_framebuffer *fb,
>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
>> +			   void *vaddr, struct drm_framebuffer *fb,
>>  			   struct drm_rect *clip)
>>  {
>>  	unsigned int cpp = fb->format->cpp[0];
>> -	unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
>> +	unsigned int offset = clip_offset(clip, dst_pitch, cpp);
>>  	size_t len = (clip->x2 - clip->x1) * cpp;
>>  	unsigned int y, lines = clip->y2 - clip->y1;
>>  
>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>  	for (y = 0; y < lines; y++) {
>>  		memcpy_toio(dst, vaddr, len);
>>  		vaddr += fb->pitches[0];
>> -		dst += fb->pitches[0];
>> +		dst += dst_pitch;
>>  	}
>>  }
>>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
>> index f16bd278ab7e..7d4f3a62d885 100644
>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
>>  	if (drm_WARN_ON(dev, !vmap))
>>  		return; /* BUG: SHMEM BO should always be vmapped */
>>  
>> -	drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
>> +	drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
>>  
>>  	drm_gem_shmem_vunmap(fb->obj[0], vmap);
>>  
>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
>> index 744a8e337e41..2dd9e5e31e3d 100644
>> --- a/drivers/gpu/drm/tiny/cirrus.c
>> +++ b/drivers/gpu/drm/tiny/cirrus.c
>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
>>  		goto out_dev_exit;
>>  
>>  	if (cirrus->cpp == fb->format->cpp[0])
>> -		drm_fb_memcpy_dstclip(cirrus->vram,
>> +		drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
>>  				      vmap, fb, rect);
>>  
>>  	else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
>> index 5f9e37032468..2b5036a5fbe7 100644
>> --- a/include/drm/drm_format_helper.h
>> +++ b/include/drm/drm_format_helper.h
>> @@ -11,7 +11,7 @@ struct drm_rect;
>>  
>>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
>>  		   struct drm_rect *clip);
>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
>>  			   struct drm_framebuffer *fb,
>>  			   struct drm_rect *clip);
>>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
>> -- 
>> 2.27.0
>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Daniel Vetter]

On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
> Hi
>
> Am 29.06.20 um 10:40 schrieb Daniel Vetter:
> > On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
> >> The memcpy's destination buffer might have a different pitch than the
> >> source. Support different pitches as function argument.
> >>
> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >
> > Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> >
> > But I do have questions ... why did we allocate a source drm_framebuffer
> > with mismatching pitch? That sounds backwards, especially for simplekms.
>
> There's userspace that allocates framebuffers in tiles of 64x64 pixels.
> I think I've seen this with Gnome. So if you have a 800x600 display
> mode, the allocated framebuffer has a scanline pitch of 832 pixels and
> the final 32 pixels are ignored.

At least with dumb buffer allocation ioctls userspace should not do
that. If it wants 800x600, it needs to allocate 800x600, not something
else. The driver is supposed to apply any rounding necessary for the
size. Or is this a buffer allocated somewhere else and then shared?
-Daniel

> In regular drivers, we can handle this with the VGA offset register [1]
> or some equivalent. That's obviously not an option with simplekms, so
> the different pitch is required.
>
> Best regards
> Thomas
>
> [1]
> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13
>
> >
> > Would be good to add the reasons why we need this to the commit message,
> > I'm sure I'll discover it later on eventually.
> > -Daniel
> >
> >> ---
> >>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
> >>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
> >>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
> >>  include/drm/drm_format_helper.h        | 2 +-
> >>  4 files changed, 8 insertions(+), 7 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> >> index c043ca364c86..8d5a683afea7 100644
> >> --- a/drivers/gpu/drm/drm_format_helper.c
> >> +++ b/drivers/gpu/drm/drm_format_helper.c
> >> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>  /**
> >>   * drm_fb_memcpy_dstclip - Copy clip buffer
> >>   * @dst: Destination buffer (iomem)
> >> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
> >>   * @vaddr: Source buffer
> >>   * @fb: DRM framebuffer
> >>   * @clip: Clip rectangle area to copy
> >> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>   * This function applies clipping on dst, i.e. the destination is a
> >>   * full (iomem) framebuffer but only the clip rect content is copied over.
> >>   */
> >> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >> -                       struct drm_framebuffer *fb,
> >> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
> >> +                       void *vaddr, struct drm_framebuffer *fb,
> >>                         struct drm_rect *clip)
> >>  {
> >>      unsigned int cpp = fb->format->cpp[0];
> >> -    unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
> >> +    unsigned int offset = clip_offset(clip, dst_pitch, cpp);
> >>      size_t len = (clip->x2 - clip->x1) * cpp;
> >>      unsigned int y, lines = clip->y2 - clip->y1;
> >>
> >> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>      for (y = 0; y < lines; y++) {
> >>              memcpy_toio(dst, vaddr, len);
> >>              vaddr += fb->pitches[0];
> >> -            dst += fb->pitches[0];
> >> +            dst += dst_pitch;
> >>      }
> >>  }
> >>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
> >> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >> index f16bd278ab7e..7d4f3a62d885 100644
> >> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> >> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
> >>      if (drm_WARN_ON(dev, !vmap))
> >>              return; /* BUG: SHMEM BO should always be vmapped */
> >>
> >> -    drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
> >> +    drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
> >>
> >>      drm_gem_shmem_vunmap(fb->obj[0], vmap);
> >>
> >> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> >> index 744a8e337e41..2dd9e5e31e3d 100644
> >> --- a/drivers/gpu/drm/tiny/cirrus.c
> >> +++ b/drivers/gpu/drm/tiny/cirrus.c
> >> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
> >>              goto out_dev_exit;
> >>
> >>      if (cirrus->cpp == fb->format->cpp[0])
> >> -            drm_fb_memcpy_dstclip(cirrus->vram,
> >> +            drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
> >>                                    vmap, fb, rect);
> >>
> >>      else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
> >> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> >> index 5f9e37032468..2b5036a5fbe7 100644
> >> --- a/include/drm/drm_format_helper.h
> >> +++ b/include/drm/drm_format_helper.h
> >> @@ -11,7 +11,7 @@ struct drm_rect;
> >>
> >>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
> >>                 struct drm_rect *clip);
> >> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
> >>                         struct drm_framebuffer *fb,
> >>                         struct drm_rect *clip);
> >>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
> >> --
> >> 2.27.0
> >>
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 6675 bytes --]

Hi

Am 26.09.20 um 18:42 schrieb Daniel Vetter:
> On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>
>> Hi
>>
>> Am 29.06.20 um 10:40 schrieb Daniel Vetter:
>>> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
>>>> The memcpy's destination buffer might have a different pitch than the
>>>> source. Support different pitches as function argument.
>>>>
>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>
>>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>
>>> But I do have questions ... why did we allocate a source drm_framebuffer
>>> with mismatching pitch? That sounds backwards, especially for simplekms.
>>
>> There's userspace that allocates framebuffers in tiles of 64x64 pixels.
>> I think I've seen this with Gnome. So if you have a 800x600 display
>> mode, the allocated framebuffer has a scanline pitch of 832 pixels and
>> the final 32 pixels are ignored.
> 
> At least with dumb buffer allocation ioctls userspace should not do
> that. If it wants 800x600, it needs to allocate 800x600, not something

That ship has sailed.

> else. The driver is supposed to apply any rounding necessary for the
> size. Or is this a buffer allocated somewhere else and then shared?

I don't quite remember where exactly this was implemented. It was not a
shared buffer, though. IIRC the buffer allocation code in one of the
libs rounded the size towards multiples of 64. I remember thinking that
it was probably done for tiled rendering.

Best regards
Thomas

> -Daniel
> 
>> In regular drivers, we can handle this with the VGA offset register [1]
>> or some equivalent. That's obviously not an option with simplekms, so
>> the different pitch is required.
>>
>> Best regards
>> Thomas
>>
>> [1]
>> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13
>>
>>>
>>> Would be good to add the reasons why we need this to the commit message,
>>> I'm sure I'll discover it later on eventually.
>>> -Daniel
>>>
>>>> ---
>>>>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
>>>>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>>>>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
>>>>  include/drm/drm_format_helper.h        | 2 +-
>>>>  4 files changed, 8 insertions(+), 7 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
>>>> index c043ca364c86..8d5a683afea7 100644
>>>> --- a/drivers/gpu/drm/drm_format_helper.c
>>>> +++ b/drivers/gpu/drm/drm_format_helper.c
>>>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>>>  /**
>>>>   * drm_fb_memcpy_dstclip - Copy clip buffer
>>>>   * @dst: Destination buffer (iomem)
>>>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
>>>>   * @vaddr: Source buffer
>>>>   * @fb: DRM framebuffer
>>>>   * @clip: Clip rectangle area to copy
>>>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>>>   * This function applies clipping on dst, i.e. the destination is a
>>>>   * full (iomem) framebuffer but only the clip rect content is copied over.
>>>>   */
>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>> -                       struct drm_framebuffer *fb,
>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
>>>> +                       void *vaddr, struct drm_framebuffer *fb,
>>>>                         struct drm_rect *clip)
>>>>  {
>>>>      unsigned int cpp = fb->format->cpp[0];
>>>> -    unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
>>>> +    unsigned int offset = clip_offset(clip, dst_pitch, cpp);
>>>>      size_t len = (clip->x2 - clip->x1) * cpp;
>>>>      unsigned int y, lines = clip->y2 - clip->y1;
>>>>
>>>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>>      for (y = 0; y < lines; y++) {
>>>>              memcpy_toio(dst, vaddr, len);
>>>>              vaddr += fb->pitches[0];
>>>> -            dst += fb->pitches[0];
>>>> +            dst += dst_pitch;
>>>>      }
>>>>  }
>>>>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
>>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>> index f16bd278ab7e..7d4f3a62d885 100644
>>>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
>>>>      if (drm_WARN_ON(dev, !vmap))
>>>>              return; /* BUG: SHMEM BO should always be vmapped */
>>>>
>>>> -    drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
>>>> +    drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
>>>>
>>>>      drm_gem_shmem_vunmap(fb->obj[0], vmap);
>>>>
>>>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
>>>> index 744a8e337e41..2dd9e5e31e3d 100644
>>>> --- a/drivers/gpu/drm/tiny/cirrus.c
>>>> +++ b/drivers/gpu/drm/tiny/cirrus.c
>>>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
>>>>              goto out_dev_exit;
>>>>
>>>>      if (cirrus->cpp == fb->format->cpp[0])
>>>> -            drm_fb_memcpy_dstclip(cirrus->vram,
>>>> +            drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
>>>>                                    vmap, fb, rect);
>>>>
>>>>      else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
>>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
>>>> index 5f9e37032468..2b5036a5fbe7 100644
>>>> --- a/include/drm/drm_format_helper.h
>>>> +++ b/include/drm/drm_format_helper.h
>>>> @@ -11,7 +11,7 @@ struct drm_rect;
>>>>
>>>>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
>>>>                 struct drm_rect *clip);
>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
>>>>                         struct drm_framebuffer *fb,
>>>>                         struct drm_rect *clip);
>>>>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
>>>> --
>>>> 2.27.0
>>>>
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Felix Imendörffer
>>
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Daniel Vetter]

On Mon, Sep 28, 2020 at 9:22 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
> Hi
>
> Am 26.09.20 um 18:42 schrieb Daniel Vetter:
> > On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> >>
> >> Hi
> >>
> >> Am 29.06.20 um 10:40 schrieb Daniel Vetter:
> >>> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
> >>>> The memcpy's destination buffer might have a different pitch than the
> >>>> source. Support different pitches as function argument.
> >>>>
> >>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >>>
> >>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> >>>
> >>> But I do have questions ... why did we allocate a source drm_framebuffer
> >>> with mismatching pitch? That sounds backwards, especially for simplekms.
> >>
> >> There's userspace that allocates framebuffers in tiles of 64x64 pixels.
> >> I think I've seen this with Gnome. So if you have a 800x600 display
> >> mode, the allocated framebuffer has a scanline pitch of 832 pixels and
> >> the final 32 pixels are ignored.
> >
> > At least with dumb buffer allocation ioctls userspace should not do
> > that. If it wants 800x600, it needs to allocate 800x600, not something
>
> That ship has sailed.

Not really, right now that ship is simply leaking and sinking. If we
decide to patch this up from the kernel side, then indeed it has
sailed. And I'm not sure that's a good idea.

> > else. The driver is supposed to apply any rounding necessary for the
> > size. Or is this a buffer allocated somewhere else and then shared?
>
> I don't quite remember where exactly this was implemented. It was not a
> shared buffer, though. IIRC the buffer allocation code in one of the
> libs rounded the size towards multiples of 64. I remember thinking that
> it was probably done for tiled rendering.

Yeah, but you don't do rendering on dumb buffers. Like ever. So this
smells like a userspace bug.

If it's for shared buffers then I think that sounds more reasonable.
-Daniel

>
> Best regards
> Thomas
>
> > -Daniel
> >
> >> In regular drivers, we can handle this with the VGA offset register [1]
> >> or some equivalent. That's obviously not an option with simplekms, so
> >> the different pitch is required.
> >>
> >> Best regards
> >> Thomas
> >>
> >> [1]
> >> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13
> >>
> >>>
> >>> Would be good to add the reasons why we need this to the commit message,
> >>> I'm sure I'll discover it later on eventually.
> >>> -Daniel
> >>>
> >>>> ---
> >>>>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
> >>>>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
> >>>>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
> >>>>  include/drm/drm_format_helper.h        | 2 +-
> >>>>  4 files changed, 8 insertions(+), 7 deletions(-)
> >>>>
> >>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> >>>> index c043ca364c86..8d5a683afea7 100644
> >>>> --- a/drivers/gpu/drm/drm_format_helper.c
> >>>> +++ b/drivers/gpu/drm/drm_format_helper.c
> >>>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>>>  /**
> >>>>   * drm_fb_memcpy_dstclip - Copy clip buffer
> >>>>   * @dst: Destination buffer (iomem)
> >>>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
> >>>>   * @vaddr: Source buffer
> >>>>   * @fb: DRM framebuffer
> >>>>   * @clip: Clip rectangle area to copy
> >>>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>>>   * This function applies clipping on dst, i.e. the destination is a
> >>>>   * full (iomem) framebuffer but only the clip rect content is copied over.
> >>>>   */
> >>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>> -                       struct drm_framebuffer *fb,
> >>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
> >>>> +                       void *vaddr, struct drm_framebuffer *fb,
> >>>>                         struct drm_rect *clip)
> >>>>  {
> >>>>      unsigned int cpp = fb->format->cpp[0];
> >>>> -    unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
> >>>> +    unsigned int offset = clip_offset(clip, dst_pitch, cpp);
> >>>>      size_t len = (clip->x2 - clip->x1) * cpp;
> >>>>      unsigned int y, lines = clip->y2 - clip->y1;
> >>>>
> >>>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>>      for (y = 0; y < lines; y++) {
> >>>>              memcpy_toio(dst, vaddr, len);
> >>>>              vaddr += fb->pitches[0];
> >>>> -            dst += fb->pitches[0];
> >>>> +            dst += dst_pitch;
> >>>>      }
> >>>>  }
> >>>>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
> >>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>> index f16bd278ab7e..7d4f3a62d885 100644
> >>>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
> >>>>      if (drm_WARN_ON(dev, !vmap))
> >>>>              return; /* BUG: SHMEM BO should always be vmapped */
> >>>>
> >>>> -    drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
> >>>> +    drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
> >>>>
> >>>>      drm_gem_shmem_vunmap(fb->obj[0], vmap);
> >>>>
> >>>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> >>>> index 744a8e337e41..2dd9e5e31e3d 100644
> >>>> --- a/drivers/gpu/drm/tiny/cirrus.c
> >>>> +++ b/drivers/gpu/drm/tiny/cirrus.c
> >>>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
> >>>>              goto out_dev_exit;
> >>>>
> >>>>      if (cirrus->cpp == fb->format->cpp[0])
> >>>> -            drm_fb_memcpy_dstclip(cirrus->vram,
> >>>> +            drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
> >>>>                                    vmap, fb, rect);
> >>>>
> >>>>      else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
> >>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> >>>> index 5f9e37032468..2b5036a5fbe7 100644
> >>>> --- a/include/drm/drm_format_helper.h
> >>>> +++ b/include/drm/drm_format_helper.h
> >>>> @@ -11,7 +11,7 @@ struct drm_rect;
> >>>>
> >>>>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
> >>>>                 struct drm_rect *clip);
> >>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
> >>>>                         struct drm_framebuffer *fb,
> >>>>                         struct drm_rect *clip);
> >>>>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
> >>>> --
> >>>> 2.27.0
> >>>>
> >>>
> >>
> >> --
> >> Thomas Zimmermann
> >> Graphics Driver Developer
> >> SUSE Software Solutions Germany GmbH
> >> Maxfeldstr. 5, 90409 Nürnberg, Germany
> >> (HRB 36809, AG Nürnberg)
> >> Geschäftsführer: Felix Imendörffer
> >>
> >
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 8125 bytes --]

Hi

Am 28.09.20 um 10:53 schrieb Daniel Vetter:
> On Mon, Sep 28, 2020 at 9:22 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>
>> Hi
>>
>> Am 26.09.20 um 18:42 schrieb Daniel Vetter:
>>> On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>>>
>>>> Hi
>>>>
>>>> Am 29.06.20 um 10:40 schrieb Daniel Vetter:
>>>>> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
>>>>>> The memcpy's destination buffer might have a different pitch than the
>>>>>> source. Support different pitches as function argument.
>>>>>>
>>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>>>
>>>>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>>>
>>>>> But I do have questions ... why did we allocate a source drm_framebuffer
>>>>> with mismatching pitch? That sounds backwards, especially for simplekms.
>>>>
>>>> There's userspace that allocates framebuffers in tiles of 64x64 pixels.
>>>> I think I've seen this with Gnome. So if you have a 800x600 display
>>>> mode, the allocated framebuffer has a scanline pitch of 832 pixels and
>>>> the final 32 pixels are ignored.
>>>
>>> At least with dumb buffer allocation ioctls userspace should not do
>>> that. If it wants 800x600, it needs to allocate 800x600, not something
>>
>> That ship has sailed.
> 
> Not really, right now that ship is simply leaking and sinking. If we
> decide to patch this up from the kernel side, then indeed it has
> sailed. And I'm not sure that's a good idea.

We have code in at least cirrus, ast and mgag200 to support this. And
userspace has been behaving like this since at least when I got involved
(2017).

> 
>>> else. The driver is supposed to apply any rounding necessary for the
>>> size. Or is this a buffer allocated somewhere else and then shared?
>>
>> I don't quite remember where exactly this was implemented. It was not a
>> shared buffer, though. IIRC the buffer allocation code in one of the
>> libs rounded the size towards multiples of 64. I remember thinking that
>> it was probably done for tiled rendering.
> 
> Yeah, but you don't do rendering on dumb buffers. Like ever. So this
> smells like a userspace bug.

It's also part of the software rendering. It is not a bug, but
implemented deliberately in one of the userspace components that
allocates framebuffers (but I cannot remember which one.)

Best regards
Thomas

> 
> If it's for shared buffers then I think that sounds more reasonable.
> -Daniel
> 
>>
>> Best regards
>> Thomas
>>
>>> -Daniel
>>>
>>>> In regular drivers, we can handle this with the VGA offset register [1]
>>>> or some equivalent. That's obviously not an option with simplekms, so
>>>> the different pitch is required.
>>>>
>>>> Best regards
>>>> Thomas
>>>>
>>>> [1]
>>>> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13
>>>>
>>>>>
>>>>> Would be good to add the reasons why we need this to the commit message,
>>>>> I'm sure I'll discover it later on eventually.
>>>>> -Daniel
>>>>>
>>>>>> ---
>>>>>>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
>>>>>>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>>>>>>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
>>>>>>  include/drm/drm_format_helper.h        | 2 +-
>>>>>>  4 files changed, 8 insertions(+), 7 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
>>>>>> index c043ca364c86..8d5a683afea7 100644
>>>>>> --- a/drivers/gpu/drm/drm_format_helper.c
>>>>>> +++ b/drivers/gpu/drm/drm_format_helper.c
>>>>>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>>>>>  /**
>>>>>>   * drm_fb_memcpy_dstclip - Copy clip buffer
>>>>>>   * @dst: Destination buffer (iomem)
>>>>>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
>>>>>>   * @vaddr: Source buffer
>>>>>>   * @fb: DRM framebuffer
>>>>>>   * @clip: Clip rectangle area to copy
>>>>>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>>>>>   * This function applies clipping on dst, i.e. the destination is a
>>>>>>   * full (iomem) framebuffer but only the clip rect content is copied over.
>>>>>>   */
>>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>>>> -                       struct drm_framebuffer *fb,
>>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
>>>>>> +                       void *vaddr, struct drm_framebuffer *fb,
>>>>>>                         struct drm_rect *clip)
>>>>>>  {
>>>>>>      unsigned int cpp = fb->format->cpp[0];
>>>>>> -    unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
>>>>>> +    unsigned int offset = clip_offset(clip, dst_pitch, cpp);
>>>>>>      size_t len = (clip->x2 - clip->x1) * cpp;
>>>>>>      unsigned int y, lines = clip->y2 - clip->y1;
>>>>>>
>>>>>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>>>>      for (y = 0; y < lines; y++) {
>>>>>>              memcpy_toio(dst, vaddr, len);
>>>>>>              vaddr += fb->pitches[0];
>>>>>> -            dst += fb->pitches[0];
>>>>>> +            dst += dst_pitch;
>>>>>>      }
>>>>>>  }
>>>>>>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
>>>>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>>>> index f16bd278ab7e..7d4f3a62d885 100644
>>>>>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>>>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>>>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
>>>>>>      if (drm_WARN_ON(dev, !vmap))
>>>>>>              return; /* BUG: SHMEM BO should always be vmapped */
>>>>>>
>>>>>> -    drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
>>>>>> +    drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
>>>>>>
>>>>>>      drm_gem_shmem_vunmap(fb->obj[0], vmap);
>>>>>>
>>>>>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
>>>>>> index 744a8e337e41..2dd9e5e31e3d 100644
>>>>>> --- a/drivers/gpu/drm/tiny/cirrus.c
>>>>>> +++ b/drivers/gpu/drm/tiny/cirrus.c
>>>>>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
>>>>>>              goto out_dev_exit;
>>>>>>
>>>>>>      if (cirrus->cpp == fb->format->cpp[0])
>>>>>> -            drm_fb_memcpy_dstclip(cirrus->vram,
>>>>>> +            drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
>>>>>>                                    vmap, fb, rect);
>>>>>>
>>>>>>      else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
>>>>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
>>>>>> index 5f9e37032468..2b5036a5fbe7 100644
>>>>>> --- a/include/drm/drm_format_helper.h
>>>>>> +++ b/include/drm/drm_format_helper.h
>>>>>> @@ -11,7 +11,7 @@ struct drm_rect;
>>>>>>
>>>>>>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
>>>>>>                 struct drm_rect *clip);
>>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
>>>>>>                         struct drm_framebuffer *fb,
>>>>>>                         struct drm_rect *clip);
>>>>>>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
>>>>>> --
>>>>>> 2.27.0
>>>>>>
>>>>>
>>>>
>>>> --
>>>> Thomas Zimmermann
>>>> Graphics Driver Developer
>>>> SUSE Software Solutions Germany GmbH
>>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>>>> (HRB 36809, AG Nürnberg)
>>>> Geschäftsführer: Felix Imendörffer
>>>>
>>>
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Felix Imendörffer
>>
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Daniel Vetter]

On Mon, Sep 28, 2020 at 11:13:06AM +0200, Thomas Zimmermann wrote:
> Hi
> 
> Am 28.09.20 um 10:53 schrieb Daniel Vetter:
> > On Mon, Sep 28, 2020 at 9:22 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> >>
> >> Hi
> >>
> >> Am 26.09.20 um 18:42 schrieb Daniel Vetter:
> >>> On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> >>>>
> >>>> Hi
> >>>>
> >>>> Am 29.06.20 um 10:40 schrieb Daniel Vetter:
> >>>>> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
> >>>>>> The memcpy's destination buffer might have a different pitch than the
> >>>>>> source. Support different pitches as function argument.
> >>>>>>
> >>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >>>>>
> >>>>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> >>>>>
> >>>>> But I do have questions ... why did we allocate a source drm_framebuffer
> >>>>> with mismatching pitch? That sounds backwards, especially for simplekms.
> >>>>
> >>>> There's userspace that allocates framebuffers in tiles of 64x64 pixels.
> >>>> I think I've seen this with Gnome. So if you have a 800x600 display
> >>>> mode, the allocated framebuffer has a scanline pitch of 832 pixels and
> >>>> the final 32 pixels are ignored.
> >>>
> >>> At least with dumb buffer allocation ioctls userspace should not do
> >>> that. If it wants 800x600, it needs to allocate 800x600, not something
> >>
> >> That ship has sailed.
> > 
> > Not really, right now that ship is simply leaking and sinking. If we
> > decide to patch this up from the kernel side, then indeed it has
> > sailed. And I'm not sure that's a good idea.
> 
> We have code in at least cirrus, ast and mgag200 to support this. And
> userspace has been behaving like this since at least when I got involved
> (2017).

Hm where do these drivers copy stuff around and rematch the stride?

> >>> else. The driver is supposed to apply any rounding necessary for the
> >>> size. Or is this a buffer allocated somewhere else and then shared?
> >>
> >> I don't quite remember where exactly this was implemented. It was not a
> >> shared buffer, though. IIRC the buffer allocation code in one of the
> >> libs rounded the size towards multiples of 64. I remember thinking that
> >> it was probably done for tiled rendering.
> > 
> > Yeah, but you don't do rendering on dumb buffers. Like ever. So this
> > smells like a userspace bug.
> 
> It's also part of the software rendering. It is not a bug, but
> implemented deliberately in one of the userspace components that
> allocates framebuffers (but I cannot remember which one.)

I think it would be good to document this.

We already fake xrgb8888 everywhere because userspace is not flexible
enough, I guess having to fake 64b stride support everywhere isn't that
much worse.

But it's definitely not great either :-/
-Daniel

> 
> Best regards
> Thomas
> 
> > 
> > If it's for shared buffers then I think that sounds more reasonable.
> > -Daniel
> > 
> >>
> >> Best regards
> >> Thomas
> >>
> >>> -Daniel
> >>>
> >>>> In regular drivers, we can handle this with the VGA offset register [1]
> >>>> or some equivalent. That's obviously not an option with simplekms, so
> >>>> the different pitch is required.
> >>>>
> >>>> Best regards
> >>>> Thomas
> >>>>
> >>>> [1]
> >>>> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13
> >>>>
> >>>>>
> >>>>> Would be good to add the reasons why we need this to the commit message,
> >>>>> I'm sure I'll discover it later on eventually.
> >>>>> -Daniel
> >>>>>
> >>>>>> ---
> >>>>>>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
> >>>>>>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
> >>>>>>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
> >>>>>>  include/drm/drm_format_helper.h        | 2 +-
> >>>>>>  4 files changed, 8 insertions(+), 7 deletions(-)
> >>>>>>
> >>>>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> >>>>>> index c043ca364c86..8d5a683afea7 100644
> >>>>>> --- a/drivers/gpu/drm/drm_format_helper.c
> >>>>>> +++ b/drivers/gpu/drm/drm_format_helper.c
> >>>>>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>>>>>  /**
> >>>>>>   * drm_fb_memcpy_dstclip - Copy clip buffer
> >>>>>>   * @dst: Destination buffer (iomem)
> >>>>>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
> >>>>>>   * @vaddr: Source buffer
> >>>>>>   * @fb: DRM framebuffer
> >>>>>>   * @clip: Clip rectangle area to copy
> >>>>>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>>>>>   * This function applies clipping on dst, i.e. the destination is a
> >>>>>>   * full (iomem) framebuffer but only the clip rect content is copied over.
> >>>>>>   */
> >>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>>>> -                       struct drm_framebuffer *fb,
> >>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
> >>>>>> +                       void *vaddr, struct drm_framebuffer *fb,
> >>>>>>                         struct drm_rect *clip)
> >>>>>>  {
> >>>>>>      unsigned int cpp = fb->format->cpp[0];
> >>>>>> -    unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
> >>>>>> +    unsigned int offset = clip_offset(clip, dst_pitch, cpp);
> >>>>>>      size_t len = (clip->x2 - clip->x1) * cpp;
> >>>>>>      unsigned int y, lines = clip->y2 - clip->y1;
> >>>>>>
> >>>>>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>>>>      for (y = 0; y < lines; y++) {
> >>>>>>              memcpy_toio(dst, vaddr, len);
> >>>>>>              vaddr += fb->pitches[0];
> >>>>>> -            dst += fb->pitches[0];
> >>>>>> +            dst += dst_pitch;
> >>>>>>      }
> >>>>>>  }
> >>>>>>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
> >>>>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>>>> index f16bd278ab7e..7d4f3a62d885 100644
> >>>>>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>>>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>>>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
> >>>>>>      if (drm_WARN_ON(dev, !vmap))
> >>>>>>              return; /* BUG: SHMEM BO should always be vmapped */
> >>>>>>
> >>>>>> -    drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
> >>>>>> +    drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
> >>>>>>
> >>>>>>      drm_gem_shmem_vunmap(fb->obj[0], vmap);
> >>>>>>
> >>>>>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> >>>>>> index 744a8e337e41..2dd9e5e31e3d 100644
> >>>>>> --- a/drivers/gpu/drm/tiny/cirrus.c
> >>>>>> +++ b/drivers/gpu/drm/tiny/cirrus.c
> >>>>>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
> >>>>>>              goto out_dev_exit;
> >>>>>>
> >>>>>>      if (cirrus->cpp == fb->format->cpp[0])
> >>>>>> -            drm_fb_memcpy_dstclip(cirrus->vram,
> >>>>>> +            drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
> >>>>>>                                    vmap, fb, rect);
> >>>>>>
> >>>>>>      else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
> >>>>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> >>>>>> index 5f9e37032468..2b5036a5fbe7 100644
> >>>>>> --- a/include/drm/drm_format_helper.h
> >>>>>> +++ b/include/drm/drm_format_helper.h
> >>>>>> @@ -11,7 +11,7 @@ struct drm_rect;
> >>>>>>
> >>>>>>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
> >>>>>>                 struct drm_rect *clip);
> >>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
> >>>>>>                         struct drm_framebuffer *fb,
> >>>>>>                         struct drm_rect *clip);
> >>>>>>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
> >>>>>> --
> >>>>>> 2.27.0
> >>>>>>
> >>>>>
> >>>>
> >>>> --
> >>>> Thomas Zimmermann
> >>>> Graphics Driver Developer
> >>>> SUSE Software Solutions Germany GmbH
> >>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
> >>>> (HRB 36809, AG Nürnberg)
> >>>> Geschäftsführer: Felix Imendörffer
> >>>>
> >>>
> >>>
> >>
> >> --
> >> Thomas Zimmermann
> >> Graphics Driver Developer
> >> SUSE Software Solutions Germany GmbH
> >> Maxfeldstr. 5, 90409 Nürnberg, Germany
> >> (HRB 36809, AG Nürnberg)
> >> Geschäftsführer: Felix Imendörffer
> >>
> > 
> > 
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
> 




-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Thomas Zimmermann]

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Hi

Am 29.09.20 um 11:19 schrieb Daniel Vetter:
> On Mon, Sep 28, 2020 at 11:13:06AM +0200, Thomas Zimmermann wrote:
>> Hi
>>
>> Am 28.09.20 um 10:53 schrieb Daniel Vetter:
>>> On Mon, Sep 28, 2020 at 9:22 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>>>
>>>> Hi
>>>>
>>>> Am 26.09.20 um 18:42 schrieb Daniel Vetter:
>>>>> On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>>>>>
>>>>>> Hi
>>>>>>
>>>>>> Am 29.06.20 um 10:40 schrieb Daniel Vetter:
>>>>>>> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
>>>>>>>> The memcpy's destination buffer might have a different pitch than the
>>>>>>>> source. Support different pitches as function argument.
>>>>>>>>
>>>>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>>>>>
>>>>>>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>>>>>
>>>>>>> But I do have questions ... why did we allocate a source drm_framebuffer
>>>>>>> with mismatching pitch? That sounds backwards, especially for simplekms.
>>>>>>
>>>>>> There's userspace that allocates framebuffers in tiles of 64x64 pixels.
>>>>>> I think I've seen this with Gnome. So if you have a 800x600 display
>>>>>> mode, the allocated framebuffer has a scanline pitch of 832 pixels and
>>>>>> the final 32 pixels are ignored.
>>>>>
>>>>> At least with dumb buffer allocation ioctls userspace should not do
>>>>> that. If it wants 800x600, it needs to allocate 800x600, not something
>>>>
>>>> That ship has sailed.
>>>
>>> Not really, right now that ship is simply leaking and sinking. If we
>>> decide to patch this up from the kernel side, then indeed it has
>>> sailed. And I'm not sure that's a good idea.
>>
>> We have code in at least cirrus, ast and mgag200 to support this. And
>> userspace has been behaving like this since at least when I got involved
>> (2017).
> 
> Hm where do these drivers copy stuff around and rematch the stride?

They don't. These drivers adopt their HW stride to match whatever
userspace framebuffers tell them. [1] And that's because userspace gives
them framebuffer sizes like 832*640. And then they do a memcpy with the
given width.

My sole point here was that userspace already relies on this behavior.

Best regards
Thomas

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/tiny/cirrus.c#n285

> 
>>>>> else. The driver is supposed to apply any rounding necessary for the
>>>>> size. Or is this a buffer allocated somewhere else and then shared?
>>>>
>>>> I don't quite remember where exactly this was implemented. It was not a
>>>> shared buffer, though. IIRC the buffer allocation code in one of the
>>>> libs rounded the size towards multiples of 64. I remember thinking that
>>>> it was probably done for tiled rendering.
>>>
>>> Yeah, but you don't do rendering on dumb buffers. Like ever. So this
>>> smells like a userspace bug.
>>
>> It's also part of the software rendering. It is not a bug, but
>> implemented deliberately in one of the userspace components that
>> allocates framebuffers (but I cannot remember which one.)
> 
> I think it would be good to document this.
> 
> We already fake xrgb8888 everywhere because userspace is not flexible
> enough, I guess having to fake 64b stride support everywhere isn't that
> much worse.
> 
> But it's definitely not great either :-/
> -Daniel
> 
>>
>> Best regards
>> Thomas
>>
>>>
>>> If it's for shared buffers then I think that sounds more reasonable.
>>> -Daniel
>>>
>>>>
>>>> Best regards
>>>> Thomas
>>>>
>>>>> -Daniel
>>>>>
>>>>>> In regular drivers, we can handle this with the VGA offset register [1]
>>>>>> or some equivalent. That's obviously not an option with simplekms, so
>>>>>> the different pitch is required.
>>>>>>
>>>>>> Best regards
>>>>>> Thomas
>>>>>>
>>>>>> [1]
>>>>>> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13
>>>>>>
>>>>>>>
>>>>>>> Would be good to add the reasons why we need this to the commit message,
>>>>>>> I'm sure I'll discover it later on eventually.
>>>>>>> -Daniel
>>>>>>>
>>>>>>>> ---
>>>>>>>>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
>>>>>>>>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
>>>>>>>>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
>>>>>>>>  include/drm/drm_format_helper.h        | 2 +-
>>>>>>>>  4 files changed, 8 insertions(+), 7 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
>>>>>>>> index c043ca364c86..8d5a683afea7 100644
>>>>>>>> --- a/drivers/gpu/drm/drm_format_helper.c
>>>>>>>> +++ b/drivers/gpu/drm/drm_format_helper.c
>>>>>>>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>>>>>>>  /**
>>>>>>>>   * drm_fb_memcpy_dstclip - Copy clip buffer
>>>>>>>>   * @dst: Destination buffer (iomem)
>>>>>>>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
>>>>>>>>   * @vaddr: Source buffer
>>>>>>>>   * @fb: DRM framebuffer
>>>>>>>>   * @clip: Clip rectangle area to copy
>>>>>>>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
>>>>>>>>   * This function applies clipping on dst, i.e. the destination is a
>>>>>>>>   * full (iomem) framebuffer but only the clip rect content is copied over.
>>>>>>>>   */
>>>>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>>>>>> -                       struct drm_framebuffer *fb,
>>>>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
>>>>>>>> +                       void *vaddr, struct drm_framebuffer *fb,
>>>>>>>>                         struct drm_rect *clip)
>>>>>>>>  {
>>>>>>>>      unsigned int cpp = fb->format->cpp[0];
>>>>>>>> -    unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
>>>>>>>> +    unsigned int offset = clip_offset(clip, dst_pitch, cpp);
>>>>>>>>      size_t len = (clip->x2 - clip->x1) * cpp;
>>>>>>>>      unsigned int y, lines = clip->y2 - clip->y1;
>>>>>>>>
>>>>>>>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>>>>>>      for (y = 0; y < lines; y++) {
>>>>>>>>              memcpy_toio(dst, vaddr, len);
>>>>>>>>              vaddr += fb->pitches[0];
>>>>>>>> -            dst += fb->pitches[0];
>>>>>>>> +            dst += dst_pitch;
>>>>>>>>      }
>>>>>>>>  }
>>>>>>>>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
>>>>>>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>>>>>> index f16bd278ab7e..7d4f3a62d885 100644
>>>>>>>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>>>>>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
>>>>>>>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
>>>>>>>>      if (drm_WARN_ON(dev, !vmap))
>>>>>>>>              return; /* BUG: SHMEM BO should always be vmapped */
>>>>>>>>
>>>>>>>> -    drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
>>>>>>>> +    drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
>>>>>>>>
>>>>>>>>      drm_gem_shmem_vunmap(fb->obj[0], vmap);
>>>>>>>>
>>>>>>>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
>>>>>>>> index 744a8e337e41..2dd9e5e31e3d 100644
>>>>>>>> --- a/drivers/gpu/drm/tiny/cirrus.c
>>>>>>>> +++ b/drivers/gpu/drm/tiny/cirrus.c
>>>>>>>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
>>>>>>>>              goto out_dev_exit;
>>>>>>>>
>>>>>>>>      if (cirrus->cpp == fb->format->cpp[0])
>>>>>>>> -            drm_fb_memcpy_dstclip(cirrus->vram,
>>>>>>>> +            drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
>>>>>>>>                                    vmap, fb, rect);
>>>>>>>>
>>>>>>>>      else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
>>>>>>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
>>>>>>>> index 5f9e37032468..2b5036a5fbe7 100644
>>>>>>>> --- a/include/drm/drm_format_helper.h
>>>>>>>> +++ b/include/drm/drm_format_helper.h
>>>>>>>> @@ -11,7 +11,7 @@ struct drm_rect;
>>>>>>>>
>>>>>>>>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
>>>>>>>>                 struct drm_rect *clip);
>>>>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
>>>>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
>>>>>>>>                         struct drm_framebuffer *fb,
>>>>>>>>                         struct drm_rect *clip);
>>>>>>>>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
>>>>>>>> --
>>>>>>>> 2.27.0
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>> --
>>>>>> Thomas Zimmermann
>>>>>> Graphics Driver Developer
>>>>>> SUSE Software Solutions Germany GmbH
>>>>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>>>>>> (HRB 36809, AG Nürnberg)
>>>>>> Geschäftsführer: Felix Imendörffer
>>>>>>
>>>>>
>>>>>
>>>>
>>>> --
>>>> Thomas Zimmermann
>>>> Graphics Driver Developer
>>>> SUSE Software Solutions Germany GmbH
>>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>>>> (HRB 36809, AG Nürnberg)
>>>> Geschäftsführer: Felix Imendörffer
>>>>
>>>
>>>
>>
>> -- 
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Felix Imendörffer
>>
> 
> 
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Daniel Vetter]

On Tue, Sep 29, 2020 at 11:39:21AM +0200, Thomas Zimmermann wrote:
> Hi
> 
> Am 29.09.20 um 11:19 schrieb Daniel Vetter:
> > On Mon, Sep 28, 2020 at 11:13:06AM +0200, Thomas Zimmermann wrote:
> >> Hi
> >>
> >> Am 28.09.20 um 10:53 schrieb Daniel Vetter:
> >>> On Mon, Sep 28, 2020 at 9:22 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> >>>>
> >>>> Hi
> >>>>
> >>>> Am 26.09.20 um 18:42 schrieb Daniel Vetter:
> >>>>> On Fri, Sep 25, 2020 at 4:55 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> >>>>>>
> >>>>>> Hi
> >>>>>>
> >>>>>> Am 29.06.20 um 10:40 schrieb Daniel Vetter:
> >>>>>>> On Thu, Jun 25, 2020 at 02:00:03PM +0200, Thomas Zimmermann wrote:
> >>>>>>>> The memcpy's destination buffer might have a different pitch than the
> >>>>>>>> source. Support different pitches as function argument.
> >>>>>>>>
> >>>>>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >>>>>>>
> >>>>>>> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> >>>>>>>
> >>>>>>> But I do have questions ... why did we allocate a source drm_framebuffer
> >>>>>>> with mismatching pitch? That sounds backwards, especially for simplekms.
> >>>>>>
> >>>>>> There's userspace that allocates framebuffers in tiles of 64x64 pixels.
> >>>>>> I think I've seen this with Gnome. So if you have a 800x600 display
> >>>>>> mode, the allocated framebuffer has a scanline pitch of 832 pixels and
> >>>>>> the final 32 pixels are ignored.
> >>>>>
> >>>>> At least with dumb buffer allocation ioctls userspace should not do
> >>>>> that. If it wants 800x600, it needs to allocate 800x600, not something
> >>>>
> >>>> That ship has sailed.
> >>>
> >>> Not really, right now that ship is simply leaking and sinking. If we
> >>> decide to patch this up from the kernel side, then indeed it has
> >>> sailed. And I'm not sure that's a good idea.
> >>
> >> We have code in at least cirrus, ast and mgag200 to support this. And
> >> userspace has been behaving like this since at least when I got involved
> >> (2017).
> > 
> > Hm where do these drivers copy stuff around and rematch the stride?
> 
> They don't. These drivers adopt their HW stride to match whatever
> userspace framebuffers tell them. [1] And that's because userspace gives
> them framebuffer sizes like 832*640. And then they do a memcpy with the
> given width.
> 
> My sole point here was that userspace already relies on this behavior.

Yeah but the problem is, if we support this through copying, then we rob
userspace of the change to do something better.

I guess the reason that userspace aligns to 64b is because of i915 gbm
(iirc 64b is the requirement for being able to render, or maybe it's the
requirement for scanout). So you get zero-copy buffer sharing.

But if the kernel now does copies on its own, without telling userspace,
then we might end up with a fairly crappy path. It might not matter much
for old devices like this one, but for cases where we really care about
zero-copy it does. And unlike the kernel userspace can perhaps do the
copying using a different gpu for these cases.

So that's kinda why I'm vary of rolling this out at large scale. Since
once we've done it, we cannot ever undo it since that breaks existing
userspace on existing hardware. Which means even if we fix userspace to
have a better/different fallback that uses a correctly sized buffer and
maybe even a gpu copy, that code wont run because the kernel papers over
the problem with a dog-slow re-stride cpu copy.
-Daniel

> 
> Best regards
> Thomas
> 
> [1]
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/tiny/cirrus.c#n285
> 
> > 
> >>>>> else. The driver is supposed to apply any rounding necessary for the
> >>>>> size. Or is this a buffer allocated somewhere else and then shared?
> >>>>
> >>>> I don't quite remember where exactly this was implemented. It was not a
> >>>> shared buffer, though. IIRC the buffer allocation code in one of the
> >>>> libs rounded the size towards multiples of 64. I remember thinking that
> >>>> it was probably done for tiled rendering.
> >>>
> >>> Yeah, but you don't do rendering on dumb buffers. Like ever. So this
> >>> smells like a userspace bug.
> >>
> >> It's also part of the software rendering. It is not a bug, but
> >> implemented deliberately in one of the userspace components that
> >> allocates framebuffers (but I cannot remember which one.)
> > 
> > I think it would be good to document this.
> > 
> > We already fake xrgb8888 everywhere because userspace is not flexible
> > enough, I guess having to fake 64b stride support everywhere isn't that
> > much worse.
> > 
> > But it's definitely not great either :-/
> > -Daniel
> > 
> >>
> >> Best regards
> >> Thomas
> >>
> >>>
> >>> If it's for shared buffers then I think that sounds more reasonable.
> >>> -Daniel
> >>>
> >>>>
> >>>> Best regards
> >>>> Thomas
> >>>>
> >>>>> -Daniel
> >>>>>
> >>>>>> In regular drivers, we can handle this with the VGA offset register [1]
> >>>>>> or some equivalent. That's obviously not an option with simplekms, so
> >>>>>> the different pitch is required.
> >>>>>>
> >>>>>> Best regards
> >>>>>> Thomas
> >>>>>>
> >>>>>> [1]
> >>>>>> https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/crtcreg.htm#13
> >>>>>>
> >>>>>>>
> >>>>>>> Would be good to add the reasons why we need this to the commit message,
> >>>>>>> I'm sure I'll discover it later on eventually.
> >>>>>>> -Daniel
> >>>>>>>
> >>>>>>>> ---
> >>>>>>>>  drivers/gpu/drm/drm_format_helper.c    | 9 +++++----
> >>>>>>>>  drivers/gpu/drm/mgag200/mgag200_mode.c | 2 +-
> >>>>>>>>  drivers/gpu/drm/tiny/cirrus.c          | 2 +-
> >>>>>>>>  include/drm/drm_format_helper.h        | 2 +-
> >>>>>>>>  4 files changed, 8 insertions(+), 7 deletions(-)
> >>>>>>>>
> >>>>>>>> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> >>>>>>>> index c043ca364c86..8d5a683afea7 100644
> >>>>>>>> --- a/drivers/gpu/drm/drm_format_helper.c
> >>>>>>>> +++ b/drivers/gpu/drm/drm_format_helper.c
> >>>>>>>> @@ -52,6 +52,7 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>>>>>>>  /**
> >>>>>>>>   * drm_fb_memcpy_dstclip - Copy clip buffer
> >>>>>>>>   * @dst: Destination buffer (iomem)
> >>>>>>>> + * @dst_pitch: Number of bytes between two consecutive scanlines within dst
> >>>>>>>>   * @vaddr: Source buffer
> >>>>>>>>   * @fb: DRM framebuffer
> >>>>>>>>   * @clip: Clip rectangle area to copy
> >>>>>>>> @@ -59,12 +60,12 @@ EXPORT_SYMBOL(drm_fb_memcpy);
> >>>>>>>>   * This function applies clipping on dst, i.e. the destination is a
> >>>>>>>>   * full (iomem) framebuffer but only the clip rect content is copied over.
> >>>>>>>>   */
> >>>>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>>>>>> -                       struct drm_framebuffer *fb,
> >>>>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch,
> >>>>>>>> +                       void *vaddr, struct drm_framebuffer *fb,
> >>>>>>>>                         struct drm_rect *clip)
> >>>>>>>>  {
> >>>>>>>>      unsigned int cpp = fb->format->cpp[0];
> >>>>>>>> -    unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
> >>>>>>>> +    unsigned int offset = clip_offset(clip, dst_pitch, cpp);
> >>>>>>>>      size_t len = (clip->x2 - clip->x1) * cpp;
> >>>>>>>>      unsigned int y, lines = clip->y2 - clip->y1;
> >>>>>>>>
> >>>>>>>> @@ -73,7 +74,7 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>>>>>>      for (y = 0; y < lines; y++) {
> >>>>>>>>              memcpy_toio(dst, vaddr, len);
> >>>>>>>>              vaddr += fb->pitches[0];
> >>>>>>>> -            dst += fb->pitches[0];
> >>>>>>>> +            dst += dst_pitch;
> >>>>>>>>      }
> >>>>>>>>  }
> >>>>>>>>  EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
> >>>>>>>> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>>>>>> index f16bd278ab7e..7d4f3a62d885 100644
> >>>>>>>> --- a/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>>>>>> +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
> >>>>>>>> @@ -1586,7 +1586,7 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
> >>>>>>>>      if (drm_WARN_ON(dev, !vmap))
> >>>>>>>>              return; /* BUG: SHMEM BO should always be vmapped */
> >>>>>>>>
> >>>>>>>> -    drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
> >>>>>>>> +    drm_fb_memcpy_dstclip(mdev->vram, fb->pitches[0], vmap, fb, clip);
> >>>>>>>>
> >>>>>>>>      drm_gem_shmem_vunmap(fb->obj[0], vmap);
> >>>>>>>>
> >>>>>>>> diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
> >>>>>>>> index 744a8e337e41..2dd9e5e31e3d 100644
> >>>>>>>> --- a/drivers/gpu/drm/tiny/cirrus.c
> >>>>>>>> +++ b/drivers/gpu/drm/tiny/cirrus.c
> >>>>>>>> @@ -327,7 +327,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
> >>>>>>>>              goto out_dev_exit;
> >>>>>>>>
> >>>>>>>>      if (cirrus->cpp == fb->format->cpp[0])
> >>>>>>>> -            drm_fb_memcpy_dstclip(cirrus->vram,
> >>>>>>>> +            drm_fb_memcpy_dstclip(cirrus->vram, fb->pitches[0],
> >>>>>>>>                                    vmap, fb, rect);
> >>>>>>>>
> >>>>>>>>      else if (fb->format->cpp[0] == 4 && cirrus->cpp == 2)
> >>>>>>>> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> >>>>>>>> index 5f9e37032468..2b5036a5fbe7 100644
> >>>>>>>> --- a/include/drm/drm_format_helper.h
> >>>>>>>> +++ b/include/drm/drm_format_helper.h
> >>>>>>>> @@ -11,7 +11,7 @@ struct drm_rect;
> >>>>>>>>
> >>>>>>>>  void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
> >>>>>>>>                 struct drm_rect *clip);
> >>>>>>>> -void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
> >>>>>>>> +void drm_fb_memcpy_dstclip(void __iomem *dst, unsigned int dst_pitch, void *vaddr,
> >>>>>>>>                         struct drm_framebuffer *fb,
> >>>>>>>>                         struct drm_rect *clip);
> >>>>>>>>  void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
> >>>>>>>> --
> >>>>>>>> 2.27.0
> >>>>>>>>
> >>>>>>>
> >>>>>>
> >>>>>> --
> >>>>>> Thomas Zimmermann
> >>>>>> Graphics Driver Developer
> >>>>>> SUSE Software Solutions Germany GmbH
> >>>>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
> >>>>>> (HRB 36809, AG Nürnberg)
> >>>>>> Geschäftsführer: Felix Imendörffer
> >>>>>>
> >>>>>
> >>>>>
> >>>>
> >>>> --
> >>>> Thomas Zimmermann
> >>>> Graphics Driver Developer
> >>>> SUSE Software Solutions Germany GmbH
> >>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
> >>>> (HRB 36809, AG Nürnberg)
> >>>> Geschäftsführer: Felix Imendörffer
> >>>>
> >>>
> >>>
> >>
> >> -- 
> >> Thomas Zimmermann
> >> Graphics Driver Developer
> >> SUSE Software Solutions Germany GmbH
> >> Maxfeldstr. 5, 90409 Nürnberg, Germany
> >> (HRB 36809, AG Nürnberg)
> >> Geschäftsführer: Felix Imendörffer
> >>
> > 
> > 
> > 
> > 
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
> 




-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Gerd Hoffmann]

  Hi,

> > I don't quite remember where exactly this was implemented. It was not a
> > shared buffer, though. IIRC the buffer allocation code in one of the
> > libs rounded the size towards multiples of 64. I remember thinking that
> > it was probably done for tiled rendering.

Happens when running gnome in wayland mode, so whatever the display
server is in that case (mutter?) or one of the libraries it uses.

> Yeah, but you don't do rendering on dumb buffers. Like ever. So this
> smells like a userspace bug.
> 
> If it's for shared buffers then I think that sounds more reasonable.

Well, wayland can use dma-bufs for buffer sharing between wayland server
and wayland client.  Dunno whenever it also does that for the software
rendering case, and I have absolutely no idea how the buffer allocation
code paths look like.  But possibly it isn't known at buffer allocation
time whenever a given buffer will be touched by a gpu at some point in
the future?

take care,
  Gerd

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Re: [PATCH 1/9] drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()

[Pekka Paalanen]

[-- Attachment #1.1: Type: text/plain, Size: 1722 bytes --]

On Mon, 28 Sep 2020 12:24:28 +0200
Gerd Hoffmann <kraxel@redhat.com> wrote:

>   Hi,
> 
> > > I don't quite remember where exactly this was implemented. It was not a
> > > shared buffer, though. IIRC the buffer allocation code in one of the
> > > libs rounded the size towards multiples of 64. I remember thinking that
> > > it was probably done for tiled rendering.  
> 
> Happens when running gnome in wayland mode, so whatever the display
> server is in that case (mutter?) or one of the libraries it uses.
> 
> > Yeah, but you don't do rendering on dumb buffers. Like ever. So this
> > smells like a userspace bug.
> > 
> > If it's for shared buffers then I think that sounds more reasonable.  
> 
> Well, wayland can use dma-bufs for buffer sharing between wayland server
> and wayland client.  Dunno whenever it also does that for the software
> rendering case, and I have absolutely no idea how the buffer allocation
> code paths look like.  But possibly it isn't known at buffer allocation
> time whenever a given buffer will be touched by a gpu at some point in
> the future?

Hi,

generally, all buffer allocation is in Mesa GBM with Mutter, even for
software rendering, as IIRC Mutter does not have a software renderer at
all, it only has (various?) GL paths.

Mutter does have code for allocating dumb buffers on "secondary GPUs"
that I touched this or last year, and I'm fairly certain that does not
do any tricks with size or stride. You also never touch that code if
you only have one DRM device in use.

Wayland apps OTOH should not have access to allocate dumb buffers in
the first place, AFAIU, unless maybe vgem or something.

Added Jonas to CC.


Thanks,
pq

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[PATCH 2/9] drm/format-helper: Add blitter functions

[Thomas Zimmermann]

The blitter functions copy a framebuffer to I/O memory using one of
the existing conversion functions.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_format_helper.c | 87 +++++++++++++++++++++++++++++
 include/drm/drm_format_helper.h     |  8 +++
 2 files changed, 95 insertions(+)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 8d5a683afea7..0e885cd34107 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -344,3 +344,90 @@ void drm_fb_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray8);
 
+/**
+ * drm_fb_blit_rect_dstclip - Copy parts of a framebuffer to display memory
+ * @dst:	The display memory to copy to
+ * @dst_pitch:	Number of bytes between two consecutive scanlines within dst
+ * @dst_format:	FOURCC code of the display's color format
+ * @vmap:	The framebuffer memory to copy from
+ * @fb:		The framebuffer to copy from
+ * @clip:	Clip rectangle area to copy
+ *
+ * This function copies parts of a framebuffer to display memory. If the
+ * formats of the display and the framebuffer mismatch, the blit function
+ * will attempt to convert between them.
+ *
+ * Use drm_fb_blit_dstclip() to copy the full framebuffer.
+ *
+ * Returns:
+ * 0 on success, or
+ * -EINVAL if the color-format conversion failed, or
+ * a negative error code otherwise.
+ */
+int drm_fb_blit_rect_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			     uint32_t dst_format, void *vmap,
+			     struct drm_framebuffer *fb,
+			     struct drm_rect *clip)
+{
+	uint32_t fb_format = fb->format->format;
+
+	/* treat alpha channel like filler bits */
+	if (fb_format == DRM_FORMAT_ARGB8888)
+		fb_format = DRM_FORMAT_XRGB8888;
+	if (dst_format == DRM_FORMAT_ARGB8888)
+		dst_format = DRM_FORMAT_XRGB8888;
+
+	if (dst_format == fb_format) {
+		drm_fb_memcpy_dstclip(dst, dst_pitch, vmap, fb, clip);
+		return 0;
+
+	} else if (dst_format == DRM_FORMAT_RGB565) {
+		if (fb_format == DRM_FORMAT_XRGB8888) {
+			drm_fb_xrgb8888_to_rgb565_dstclip(dst, dst_pitch,
+							  vmap, fb, clip,
+							  false);
+			return 0;
+		}
+	} else if (dst_format == DRM_FORMAT_RGB888) {
+		if (fb_format == DRM_FORMAT_XRGB8888) {
+			drm_fb_xrgb8888_to_rgb888_dstclip(dst, dst_pitch,
+							  vmap, fb, clip);
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL(drm_fb_blit_rect_dstclip);
+
+/**
+ * drm_fb_blit_dstclip - Copy framebuffer to display memory
+ * @dst:	The display memory to copy to
+ * @dst_pitch:	Number of bytes between two consecutive scanlines within dst
+ * @dst_format:	FOURCC code of the display's color format
+ * @vmap:	The framebuffer memory to copy from
+ * @fb:		The framebuffer to copy from
+ *
+ * This function copies a full framebuffer to display memory. If the formats
+ * of the display and the framebuffer mismatch, the copy function will
+ * attempt to convert between them.
+ *
+ * See drm_fb_blit_rect_dstclip() for more inforamtion.
+ *
+ * Returns:
+ * 0 on success, or a negative error code otherwise.
+ */
+int drm_fb_blit_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			uint32_t dst_format, void *vmap,
+			struct drm_framebuffer *fb)
+{
+	struct drm_rect fullscreen = {
+		.x1 = 0,
+		.x2 = fb->width,
+		.y1 = 0,
+		.y2 = fb->height,
+	};
+	return drm_fb_blit_rect_dstclip(dst, dst_pitch, dst_format, vmap, fb,
+					&fullscreen);
+}
+EXPORT_SYMBOL(drm_fb_blit_dstclip);
diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
index 2b5036a5fbe7..4e0258a61311 100644
--- a/include/drm/drm_format_helper.h
+++ b/include/drm/drm_format_helper.h
@@ -28,4 +28,12 @@ void drm_fb_xrgb8888_to_rgb888_dstclip(void __iomem *dst, unsigned int dst_pitch
 void drm_fb_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 			      struct drm_rect *clip);
 
+int drm_fb_blit_rect_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			     uint32_t dst_format, void *vmap,
+			     struct drm_framebuffer *fb,
+			     struct drm_rect *rect);
+int drm_fb_blit_dstclip(void __iomem *dst, unsigned int dst_pitch,
+			uint32_t dst_format, void *vmap,
+			struct drm_framebuffer *fb);
+
 #endif /* __LINUX_DRM_FORMAT_HELPER_H */
-- 
2.27.0

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Re: [PATCH 2/9] drm/format-helper: Add blitter functions

[Daniel Vetter]

On Thu, Jun 25, 2020 at 02:00:04PM +0200, Thomas Zimmermann wrote:
> The blitter functions copy a framebuffer to I/O memory using one of
> the existing conversion functions.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Hm I guess reason for adding dst_pitch in the previous patch is so that
there wouldn't be a special case here. Makes sense.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> ---
>  drivers/gpu/drm/drm_format_helper.c | 87 +++++++++++++++++++++++++++++
>  include/drm/drm_format_helper.h     |  8 +++
>  2 files changed, 95 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
> index 8d5a683afea7..0e885cd34107 100644
> --- a/drivers/gpu/drm/drm_format_helper.c
> +++ b/drivers/gpu/drm/drm_format_helper.c
> @@ -344,3 +344,90 @@ void drm_fb_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
>  }
>  EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray8);
>  
> +/**
> + * drm_fb_blit_rect_dstclip - Copy parts of a framebuffer to display memory
> + * @dst:	The display memory to copy to
> + * @dst_pitch:	Number of bytes between two consecutive scanlines within dst
> + * @dst_format:	FOURCC code of the display's color format
> + * @vmap:	The framebuffer memory to copy from
> + * @fb:		The framebuffer to copy from
> + * @clip:	Clip rectangle area to copy
> + *
> + * This function copies parts of a framebuffer to display memory. If the
> + * formats of the display and the framebuffer mismatch, the blit function
> + * will attempt to convert between them.
> + *
> + * Use drm_fb_blit_dstclip() to copy the full framebuffer.
> + *
> + * Returns:
> + * 0 on success, or
> + * -EINVAL if the color-format conversion failed, or
> + * a negative error code otherwise.
> + */
> +int drm_fb_blit_rect_dstclip(void __iomem *dst, unsigned int dst_pitch,
> +			     uint32_t dst_format, void *vmap,
> +			     struct drm_framebuffer *fb,
> +			     struct drm_rect *clip)
> +{
> +	uint32_t fb_format = fb->format->format;
> +
> +	/* treat alpha channel like filler bits */
> +	if (fb_format == DRM_FORMAT_ARGB8888)
> +		fb_format = DRM_FORMAT_XRGB8888;
> +	if (dst_format == DRM_FORMAT_ARGB8888)
> +		dst_format = DRM_FORMAT_XRGB8888;
> +
> +	if (dst_format == fb_format) {
> +		drm_fb_memcpy_dstclip(dst, dst_pitch, vmap, fb, clip);
> +		return 0;
> +
> +	} else if (dst_format == DRM_FORMAT_RGB565) {
> +		if (fb_format == DRM_FORMAT_XRGB8888) {
> +			drm_fb_xrgb8888_to_rgb565_dstclip(dst, dst_pitch,
> +							  vmap, fb, clip,
> +							  false);
> +			return 0;
> +		}
> +	} else if (dst_format == DRM_FORMAT_RGB888) {
> +		if (fb_format == DRM_FORMAT_XRGB8888) {
> +			drm_fb_xrgb8888_to_rgb888_dstclip(dst, dst_pitch,
> +							  vmap, fb, clip);
> +			return 0;
> +		}
> +	}
> +
> +	return -EINVAL;
> +}
> +EXPORT_SYMBOL(drm_fb_blit_rect_dstclip);
> +
> +/**
> + * drm_fb_blit_dstclip - Copy framebuffer to display memory
> + * @dst:	The display memory to copy to
> + * @dst_pitch:	Number of bytes between two consecutive scanlines within dst
> + * @dst_format:	FOURCC code of the display's color format
> + * @vmap:	The framebuffer memory to copy from
> + * @fb:		The framebuffer to copy from
> + *
> + * This function copies a full framebuffer to display memory. If the formats
> + * of the display and the framebuffer mismatch, the copy function will
> + * attempt to convert between them.
> + *
> + * See drm_fb_blit_rect_dstclip() for more inforamtion.
> + *
> + * Returns:
> + * 0 on success, or a negative error code otherwise.
> + */
> +int drm_fb_blit_dstclip(void __iomem *dst, unsigned int dst_pitch,
> +			uint32_t dst_format, void *vmap,
> +			struct drm_framebuffer *fb)

I do wonder whether we shouldn't have to some safety checks for this
stuff, like maybe something like:

struct dst_info {
	void __iomem *dst;
	unsigned int size;
	unsigned int dst_pitch;
	uint32_t dst_format;
};

And then the helpers would splat a WARNING if a driver ever gets this
wrong. Thinking about this because syzkaller has found tons of little
off-by-a-bit bugs in the vt/fbcon/fbdev code, and maybe we should try to
be better :-)

But that's material for another patch, and maybe once we have a few more
helpers in this library we can figure out a nice struct to package up
these long&confusing argument lists a bit.

Cheers, Daniel

> +{
> +	struct drm_rect fullscreen = {
> +		.x1 = 0,
> +		.x2 = fb->width,
> +		.y1 = 0,
> +		.y2 = fb->height,
> +	};
> +	return drm_fb_blit_rect_dstclip(dst, dst_pitch, dst_format, vmap, fb,
> +					&fullscreen);
> +}
> +EXPORT_SYMBOL(drm_fb_blit_dstclip);
> diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
> index 2b5036a5fbe7..4e0258a61311 100644
> --- a/include/drm/drm_format_helper.h
> +++ b/include/drm/drm_format_helper.h
> @@ -28,4 +28,12 @@ void drm_fb_xrgb8888_to_rgb888_dstclip(void __iomem *dst, unsigned int dst_pitch
>  void drm_fb_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
>  			      struct drm_rect *clip);
>  
> +int drm_fb_blit_rect_dstclip(void __iomem *dst, unsigned int dst_pitch,
> +			     uint32_t dst_format, void *vmap,
> +			     struct drm_framebuffer *fb,
> +			     struct drm_rect *rect);
> +int drm_fb_blit_dstclip(void __iomem *dst, unsigned int dst_pitch,
> +			uint32_t dst_format, void *vmap,
> +			struct drm_framebuffer *fb);
> +
>  #endif /* __LINUX_DRM_FORMAT_HELPER_H */
> -- 
> 2.27.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[PATCH 3/9] drm: Add simplekms driver

[Thomas Zimmermann]

The simplekms driver is a DRM driver for simplefb framebuffers as
provided by the kernel's boot code. This driver enables basic
graphical output on many different graphics devices that are provided
by the platform (e.g., EFI, VESA, embedded framebuffers).

With the kernel's simplefb infrastructure, the kernel receives a
pre-configured framebuffer from the system (i.e., firmware, boot
loader). It creates a platform device to which simplekms attaches.
The system's framebuffer consists of a memory range, size and format.
Based on these values, simplekms creates a DRM devices. No actual
modesetting is possible.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 MAINTAINERS                      |   6 +
 drivers/gpu/drm/tiny/Kconfig     |  16 +
 drivers/gpu/drm/tiny/Makefile    |   1 +
 drivers/gpu/drm/tiny/simplekms.c | 495 +++++++++++++++++++++++++++++++
 4 files changed, 518 insertions(+)
 create mode 100644 drivers/gpu/drm/tiny/simplekms.c

diff --git a/MAINTAINERS b/MAINTAINERS
index f17d99164a77..ac517dc8d05d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5505,6 +5505,12 @@ S:	Orphan / Obsolete
 F:	drivers/gpu/drm/savage/
 F:	include/uapi/drm/savage_drm.h
 
+DRM DRIVER FOR SIMPLE FRAMEBUFFERS
+M:	Thomas Zimmermann <tzimmermann@suse.de>
+S:	Maintained
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	drivers/gpu/drm/tiny/simplekms.c
+
 DRM DRIVER FOR SIS VIDEO CARDS
 S:	Orphan / Obsolete
 F:	drivers/gpu/drm/sis/
diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index 2b6414f0fa75..50dbde8bdcb2 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -28,6 +28,22 @@ config DRM_GM12U320
 	 This is a KMS driver for projectors which use the GM12U320 chipset
 	 for video transfer over USB2/3, such as the Acer C120 mini projector.
 
+config DRM_SIMPLEKMS
+	tristate "Simple framebuffer driver"
+	depends on DRM
+	select DRM_GEM_SHMEM_HELPER
+	select DRM_KMS_HELPER
+	help
+	  DRM driver for simple platform-provided framebuffers.
+
+	  This driver assumes that the display hardware has been initialized
+	  by the firmware or bootloader before the kernel boots. Scanout
+	  buffer, size, and display format must be provided via device tree,
+	  UEFI, VESA, etc.
+
+	  On x86 and compatible, you should also select CONFIG_X86_SYSFB to
+	  use UEFI and VESA framebuffers.
+
 config TINYDRM_HX8357D
 	tristate "DRM support for HX8357D display panels"
 	depends on DRM && SPI
diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
index 6ae4e9e5a35f..e83fbbfa7344 100644
--- a/drivers/gpu/drm/tiny/Makefile
+++ b/drivers/gpu/drm/tiny/Makefile
@@ -2,6 +2,7 @@
 
 obj-$(CONFIG_DRM_CIRRUS_QEMU)		+= cirrus.o
 obj-$(CONFIG_DRM_GM12U320)		+= gm12u320.o
+obj-$(CONFIG_DRM_SIMPLEKMS)		+= simplekms.o
 obj-$(CONFIG_TINYDRM_HX8357D)		+= hx8357d.o
 obj-$(CONFIG_TINYDRM_ILI9225)		+= ili9225.o
 obj-$(CONFIG_TINYDRM_ILI9341)		+= ili9341.o
diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
new file mode 100644
index 000000000000..dc7cf3983945
--- /dev/null
+++ b/drivers/gpu/drm/tiny/simplekms.c
@@ -0,0 +1,495 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/platform_data/simplefb.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#define DRIVER_NAME	"simplekms"
+#define DRIVER_DESC	"DRM driver for simple-framebuffer platform devices"
+#define DRIVER_DATE	"20200625"
+#define DRIVER_MAJOR	1
+#define DRIVER_MINOR	0
+
+/*
+ * Assume a monitor resolution of 96 dpi to
+ * get a somewhat reasonable screen size.
+ */
+#define RES_MM(d)	\
+	(((d) * 254ul) / (96ul * 10ul))
+
+#define SIMPLEKMS_MODE(hd, vd)	\
+	DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
+
+/*
+ * Helpers for simplefb
+ */
+
+static int
+simplefb_get_validated_int(struct drm_device *dev, const char *name,
+			   uint32_t value)
+{
+	if (value > INT_MAX) {
+		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
+			name, value);
+		return -EINVAL;
+	}
+	return (int)value;
+}
+
+static int
+simplefb_get_validated_int0(struct drm_device *dev, const char *name,
+			    uint32_t value)
+{
+	if (!value) {
+		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
+			name, value);
+		return -EINVAL;
+	}
+	return simplefb_get_validated_int(dev, name, value);
+}
+
+static const struct drm_format_info *
+simplefb_get_validated_format(struct drm_device *dev, const char *format_name)
+{
+	static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
+	const struct simplefb_format *fmt = formats;
+	const struct simplefb_format *end = fmt + ARRAY_SIZE(formats);
+
+	if (!format_name) {
+		drm_err(dev, "simplefb: missing framebuffer format\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	while (fmt < end) {
+		if (!strcmp(format_name, fmt->name))
+			return drm_format_info(fmt->fourcc);
+		++fmt;
+	}
+
+	drm_err(dev, "simplefb: unknown framebuffer format %s\n",
+		format_name);
+
+	return ERR_PTR(-EINVAL);
+}
+
+static int
+simplefb_get_width_pd(struct drm_device *dev,
+		      const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_int0(dev, "width", pd->width);
+}
+
+static int
+simplefb_get_height_pd(struct drm_device *dev,
+		       const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_int0(dev, "height", pd->height);
+}
+
+static int
+simplefb_get_stride_pd(struct drm_device *dev,
+		       const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_int(dev, "stride", pd->stride);
+}
+
+static const struct drm_format_info *
+simplefb_get_format_pd(struct drm_device *dev,
+		       const struct simplefb_platform_data *pd)
+{
+	return simplefb_get_validated_format(dev, pd->format);
+}
+
+/*
+ * Simple Framebuffer device
+ */
+
+struct simplekms_device {
+	struct drm_device dev;
+	struct platform_device *pdev;
+
+	/* simplefb settings */
+	struct drm_display_mode mode;
+	const struct drm_format_info *format;
+	unsigned int pitch;
+
+	/* memory management */
+	struct resource *mem;
+	void __iomem *screen_base;
+
+	/* modesetting */
+	struct drm_connector connector;
+	struct drm_simple_display_pipe pipe;
+};
+
+static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
+{
+	return container_of(dev, struct simplekms_device, dev);
+}
+
+/*
+ *  Simplefb settings
+ */
+
+static struct drm_display_mode simplekms_mode(unsigned int width,
+					      unsigned int height)
+{
+	struct drm_display_mode mode = { SIMPLEKMS_MODE(width, height) };
+
+	mode.clock = 60 /* Hz */ * mode.hdisplay * mode.vdisplay;
+	drm_mode_set_name(&mode);
+
+	return mode;
+}
+
+static int simplekms_device_init_fb(struct simplekms_device *sdev)
+{
+	int width, height, stride;
+	const struct drm_format_info *format;
+	struct drm_format_name_buf buf;
+	struct drm_device *dev = &sdev->dev;
+	struct platform_device *pdev = sdev->pdev;
+	const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
+
+	if (pd) {
+		width = simplefb_get_width_pd(dev, pd);
+		if (width < 0)
+			return width;
+		height = simplefb_get_height_pd(dev, pd);
+		if (height < 0)
+			return height;
+		stride = simplefb_get_stride_pd(dev, pd);
+		if (stride < 0)
+			return stride;
+		format = simplefb_get_format_pd(dev, pd);
+		if (IS_ERR(format))
+			return PTR_ERR(format);
+	} else {
+		drm_err(dev, "no simplefb configuration found\n");
+		return -ENODEV;
+	}
+
+	sdev->mode = simplekms_mode(width, height);
+	sdev->format = format;
+	sdev->pitch = stride;
+
+	drm_dbg_kms(dev, "display mode={" DRM_MODE_FMT "}\n",
+		    DRM_MODE_ARG(&sdev->mode));
+	drm_dbg_kms(dev,
+		    "framebuffer format=\"%s\", size=%dx%d, stride=%d byte\n",
+		    drm_get_format_name(format->format, &buf), width,
+		    height, stride);
+
+	return 0;
+}
+
+/*
+ * Memory management
+ */
+
+static int simplekms_device_init_mm(struct simplekms_device *sdev)
+{
+	struct platform_device *pdev = sdev->pdev;
+	struct resource *mem;
+	void __iomem *screen_base;
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!mem)
+		return -EINVAL;
+
+	screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
+				      resource_size(mem));
+	if (!screen_base)
+		return -ENOMEM;
+
+	sdev->mem = mem;
+	sdev->screen_base = screen_base;
+
+	return 0;
+}
+
+/*
+ * Modesetting
+ */
+
+/*
+ * Support all formats of simplefb and maybe more; in order
+ * of preference. The display's update function will do any
+ * conversion necessary.
+ *
+ * TODO: Add blit helpers for remaining formats and uncomment
+ *       constants.
+ */
+static const uint32_t simplekms_formats[] = {
+	DRM_FORMAT_XRGB8888,
+	DRM_FORMAT_ARGB8888,
+	DRM_FORMAT_RGB565,
+	//DRM_FORMAT_XRGB1555,
+	//DRM_FORMAT_ARGB1555,
+	DRM_FORMAT_RGB888,
+	//DRM_FORMAT_XRGB2101010,
+	//DRM_FORMAT_ARGB2101010,
+};
+
+static const uint64_t simplekms_format_modifiers[] = {
+	DRM_FORMAT_MOD_LINEAR,
+	DRM_FORMAT_MOD_INVALID
+};
+
+static int simplekms_connector_get_modes(struct drm_connector *connector)
+{
+	struct simplekms_device *sdev = simplekms_device_of_dev(connector->dev);
+	struct drm_display_mode *mode;
+
+	mode = drm_mode_duplicate(connector->dev, &sdev->mode);
+	if (!mode)
+                return 0;
+
+	if (mode->name[0] == '\0')
+		drm_mode_set_name(mode);
+
+	mode->type |= DRM_MODE_TYPE_PREFERRED;
+	drm_mode_probed_add(connector, mode);
+
+	if (mode->width_mm)
+                connector->display_info.width_mm = mode->width_mm;
+	if (mode->height_mm)
+                connector->display_info.height_mm = mode->height_mm;
+
+        return 1;
+}
+
+static const struct drm_connector_helper_funcs simplekms_connector_helper_funcs = {
+	.get_modes = simplekms_connector_get_modes,
+};
+
+static const struct drm_connector_funcs simplekms_connector_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = drm_connector_cleanup,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static int
+simplekms_simple_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
+				    const struct drm_display_mode *mode)
+{
+	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
+
+	if (mode->hdisplay != sdev->mode.hdisplay &&
+	    mode->vdisplay != sdev->mode.vdisplay)
+		return MODE_ONE_SIZE;
+	else if (mode->hdisplay != sdev->mode.hdisplay)
+		return MODE_ONE_WIDTH;
+	else if (mode->vdisplay != sdev->mode.vdisplay)
+		return MODE_ONE_HEIGHT;
+
+	return MODE_OK;
+}
+
+static void
+simplekms_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
+				struct drm_crtc_state *crtc_state,
+				struct drm_plane_state *plane_state)
+{
+	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_framebuffer *fb = state->fb;
+	void *vmap;
+
+	vmap = drm_gem_shmem_vmap(fb->obj[0]);
+	if (!vmap)
+		return;
+
+	drm_fb_blit_dstclip(sdev->screen_base, sdev->pitch,
+			    sdev->format->format, vmap, fb);
+
+	drm_gem_shmem_vunmap(fb->obj[0], vmap);
+}
+
+static void
+simplekms_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
+				struct drm_plane_state *old_plane_state)
+{
+	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_framebuffer *fb = state->fb;
+	struct drm_rect clip;
+	void *vmap;
+
+	if (!drm_atomic_helper_damage_merged(old_plane_state, state, &clip))
+		return;
+
+	vmap = drm_gem_shmem_vmap(fb->obj[0]);
+	if (!vmap)
+		return;
+
+	drm_fb_blit_rect_dstclip(sdev->screen_base, sdev->pitch,
+				 sdev->format->format, vmap, fb, &clip);
+
+	drm_gem_shmem_vunmap(fb->obj[0], vmap);
+}
+
+static const struct drm_simple_display_pipe_funcs
+simplekms_simple_display_pipe_funcs = {
+	.mode_valid = simplekms_simple_display_pipe_mode_valid,
+	.enable = simplekms_simple_display_pipe_enable,
+	.update = simplekms_simple_display_pipe_update,
+	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+static const struct drm_mode_config_funcs simplekms_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static int simplekms_device_init_modeset(struct simplekms_device *sdev)
+{
+	struct drm_device *dev = &sdev->dev;
+	struct drm_display_mode *mode = &sdev->mode;
+	struct drm_connector *connector = &sdev->connector;
+	struct drm_simple_display_pipe *pipe = &sdev->pipe;
+	int ret;
+
+	ret = drmm_mode_config_init(dev);
+	if (ret)
+		return ret;
+
+	dev->mode_config.min_width = mode->hdisplay;
+	dev->mode_config.max_width = mode->hdisplay;
+	dev->mode_config.min_height = mode->vdisplay;
+	dev->mode_config.max_height = mode->vdisplay;
+	dev->mode_config.prefer_shadow = true;
+	dev->mode_config.preferred_depth = sdev->format->cpp[0] * 8;
+	dev->mode_config.funcs = &simplekms_mode_config_funcs;
+
+	drm_connector_helper_add(connector, &simplekms_connector_helper_funcs);
+	ret = drm_connector_init(dev, connector, &simplekms_connector_funcs,
+				 DRM_MODE_CONNECTOR_Unknown);
+	if (ret)
+		return ret;
+
+	ret = drm_simple_display_pipe_init(dev, pipe,
+					   &simplekms_simple_display_pipe_funcs,
+					   simplekms_formats,
+					   ARRAY_SIZE(simplekms_formats),
+					   simplekms_format_modifiers,
+					   connector);
+	if (ret)
+		return ret;
+
+	drm_mode_config_reset(dev);
+
+	return 0;
+}
+
+/*
+ * Init / Cleanup
+ */
+
+static void simplekms_device_cleanup(struct simplekms_device* sdev)
+{
+	struct drm_device *dev = &sdev->dev;
+
+	drm_dev_unregister(dev);
+}
+
+static struct simplekms_device *
+simplekms_device_create(struct drm_driver *drv, struct platform_device *pdev)
+{
+	struct simplekms_device *sdev;
+	int ret;
+
+	sdev = devm_drm_dev_alloc(&pdev->dev, drv, struct simplekms_device,
+				  dev);
+	if (IS_ERR(sdev))
+		return ERR_CAST(sdev);
+	sdev->pdev = pdev;
+
+	ret = simplekms_device_init_fb(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+	ret = simplekms_device_init_mm(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+	ret = simplekms_device_init_modeset(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return sdev;
+}
+
+/*
+ * DRM driver
+ */
+
+DEFINE_DRM_GEM_FOPS(simplekms_fops);
+
+static struct drm_driver simplekms_driver = {
+	DRM_GEM_SHMEM_DRIVER_OPS,
+	.name			= DRIVER_NAME,
+	.desc			= DRIVER_DESC,
+	.date			= DRIVER_DATE,
+	.major			= DRIVER_MAJOR,
+	.minor			= DRIVER_MINOR,
+	.driver_features	= DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
+	.fops			= &simplekms_fops,
+};
+
+/*
+ * Platform driver
+ */
+
+static int simplekms_probe(struct platform_device *pdev)
+{
+	struct simplekms_device *sdev;
+	struct drm_device *dev;
+	int ret;
+
+	sdev = simplekms_device_create(&simplekms_driver, pdev);
+	if (IS_ERR(sdev))
+		return PTR_ERR(sdev);
+	dev = &sdev->dev;
+
+	ret = drm_dev_register(dev, 0);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static int simplekms_remove(struct platform_device *pdev)
+{
+	struct simplekms_device *sdev = platform_get_drvdata(pdev);
+
+	simplekms_device_cleanup(sdev);
+
+	return 0;
+}
+
+static struct platform_driver simplekms_platform_driver = {
+	.driver = {
+		.name = "simple-framebuffer", /* connect to sysfb */
+	},
+	.probe = simplekms_probe,
+	.remove = simplekms_remove,
+};
+
+module_platform_driver(simplekms_platform_driver);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL v2");
-- 
2.27.0

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: [PATCH 3/9] drm: Add simplekms driver

[Daniel Vetter]

On Thu, Jun 25, 2020 at 02:00:05PM +0200, Thomas Zimmermann wrote:
> The simplekms driver is a DRM driver for simplefb framebuffers as
> provided by the kernel's boot code. This driver enables basic
> graphical output on many different graphics devices that are provided
> by the platform (e.g., EFI, VESA, embedded framebuffers).
> 
> With the kernel's simplefb infrastructure, the kernel receives a
> pre-configured framebuffer from the system (i.e., firmware, boot
> loader). It creates a platform device to which simplekms attaches.
> The system's framebuffer consists of a memory range, size and format.
> Based on these values, simplekms creates a DRM devices. No actual
> modesetting is possible.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  MAINTAINERS                      |   6 +
>  drivers/gpu/drm/tiny/Kconfig     |  16 +
>  drivers/gpu/drm/tiny/Makefile    |   1 +
>  drivers/gpu/drm/tiny/simplekms.c | 495 +++++++++++++++++++++++++++++++
>  4 files changed, 518 insertions(+)
>  create mode 100644 drivers/gpu/drm/tiny/simplekms.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index f17d99164a77..ac517dc8d05d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5505,6 +5505,12 @@ S:	Orphan / Obsolete
>  F:	drivers/gpu/drm/savage/
>  F:	include/uapi/drm/savage_drm.h
>  
> +DRM DRIVER FOR SIMPLE FRAMEBUFFERS
> +M:	Thomas Zimmermann <tzimmermann@suse.de>
> +S:	Maintained
> +T:	git git://anongit.freedesktop.org/drm/drm-misc
> +F:	drivers/gpu/drm/tiny/simplekms.c
> +
>  DRM DRIVER FOR SIS VIDEO CARDS
>  S:	Orphan / Obsolete
>  F:	drivers/gpu/drm/sis/
> diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> index 2b6414f0fa75..50dbde8bdcb2 100644
> --- a/drivers/gpu/drm/tiny/Kconfig
> +++ b/drivers/gpu/drm/tiny/Kconfig
> @@ -28,6 +28,22 @@ config DRM_GM12U320
>  	 This is a KMS driver for projectors which use the GM12U320 chipset
>  	 for video transfer over USB2/3, such as the Acer C120 mini projector.
>  
> +config DRM_SIMPLEKMS
> +	tristate "Simple framebuffer driver"
> +	depends on DRM
> +	select DRM_GEM_SHMEM_HELPER
> +	select DRM_KMS_HELPER
> +	help
> +	  DRM driver for simple platform-provided framebuffers.
> +
> +	  This driver assumes that the display hardware has been initialized
> +	  by the firmware or bootloader before the kernel boots. Scanout
> +	  buffer, size, and display format must be provided via device tree,
> +	  UEFI, VESA, etc.
> +
> +	  On x86 and compatible, you should also select CONFIG_X86_SYSFB to
> +	  use UEFI and VESA framebuffers.
> +
>  config TINYDRM_HX8357D
>  	tristate "DRM support for HX8357D display panels"
>  	depends on DRM && SPI
> diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
> index 6ae4e9e5a35f..e83fbbfa7344 100644
> --- a/drivers/gpu/drm/tiny/Makefile
> +++ b/drivers/gpu/drm/tiny/Makefile
> @@ -2,6 +2,7 @@
>  
>  obj-$(CONFIG_DRM_CIRRUS_QEMU)		+= cirrus.o
>  obj-$(CONFIG_DRM_GM12U320)		+= gm12u320.o
> +obj-$(CONFIG_DRM_SIMPLEKMS)		+= simplekms.o
>  obj-$(CONFIG_TINYDRM_HX8357D)		+= hx8357d.o
>  obj-$(CONFIG_TINYDRM_ILI9225)		+= ili9225.o
>  obj-$(CONFIG_TINYDRM_ILI9341)		+= ili9341.o
> diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
> new file mode 100644
> index 000000000000..dc7cf3983945
> --- /dev/null
> +++ b/drivers/gpu/drm/tiny/simplekms.c
> @@ -0,0 +1,495 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/platform_data/simplefb.h>
> +#include <linux/platform_device.h>
> +
> +#include <drm/drm_atomic_state_helper.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_damage_helper.h>
> +#include <drm/drm_device.h>
> +#include <drm/drm_drv.h>
> +#include <drm/drm_format_helper.h>
> +#include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_gem_shmem_helper.h>
> +#include <drm/drm_managed.h>
> +#include <drm/drm_modeset_helper_vtables.h>
> +#include <drm/drm_probe_helper.h>
> +#include <drm/drm_simple_kms_helper.h>
> +
> +#define DRIVER_NAME	"simplekms"
> +#define DRIVER_DESC	"DRM driver for simple-framebuffer platform devices"
> +#define DRIVER_DATE	"20200625"
> +#define DRIVER_MAJOR	1
> +#define DRIVER_MINOR	0
> +
> +/*
> + * Assume a monitor resolution of 96 dpi to
> + * get a somewhat reasonable screen size.
> + */
> +#define RES_MM(d)	\
> +	(((d) * 254ul) / (96ul * 10ul))
> +
> +#define SIMPLEKMS_MODE(hd, vd)	\
> +	DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
> +
> +/*
> + * Helpers for simplefb
> + */
> +
> +static int
> +simplefb_get_validated_int(struct drm_device *dev, const char *name,
> +			   uint32_t value)
> +{
> +	if (value > INT_MAX) {
> +		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
> +			name, value);
> +		return -EINVAL;
> +	}
> +	return (int)value;
> +}
> +
> +static int
> +simplefb_get_validated_int0(struct drm_device *dev, const char *name,
> +			    uint32_t value)
> +{
> +	if (!value) {
> +		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
> +			name, value);
> +		return -EINVAL;
> +	}
> +	return simplefb_get_validated_int(dev, name, value);
> +}
> +
> +static const struct drm_format_info *
> +simplefb_get_validated_format(struct drm_device *dev, const char *format_name)
> +{
> +	static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
> +	const struct simplefb_format *fmt = formats;
> +	const struct simplefb_format *end = fmt + ARRAY_SIZE(formats);
> +
> +	if (!format_name) {
> +		drm_err(dev, "simplefb: missing framebuffer format\n");
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	while (fmt < end) {
> +		if (!strcmp(format_name, fmt->name))
> +			return drm_format_info(fmt->fourcc);
> +		++fmt;
> +	}
> +
> +	drm_err(dev, "simplefb: unknown framebuffer format %s\n",
> +		format_name);
> +
> +	return ERR_PTR(-EINVAL);
> +}
> +
> +static int
> +simplefb_get_width_pd(struct drm_device *dev,
> +		      const struct simplefb_platform_data *pd)
> +{
> +	return simplefb_get_validated_int0(dev, "width", pd->width);
> +}
> +
> +static int
> +simplefb_get_height_pd(struct drm_device *dev,
> +		       const struct simplefb_platform_data *pd)
> +{
> +	return simplefb_get_validated_int0(dev, "height", pd->height);
> +}
> +
> +static int
> +simplefb_get_stride_pd(struct drm_device *dev,
> +		       const struct simplefb_platform_data *pd)
> +{
> +	return simplefb_get_validated_int(dev, "stride", pd->stride);
> +}
> +
> +static const struct drm_format_info *
> +simplefb_get_format_pd(struct drm_device *dev,
> +		       const struct simplefb_platform_data *pd)
> +{
> +	return simplefb_get_validated_format(dev, pd->format);
> +}
> +
> +/*
> + * Simple Framebuffer device
> + */
> +
> +struct simplekms_device {
> +	struct drm_device dev;
> +	struct platform_device *pdev;
> +
> +	/* simplefb settings */
> +	struct drm_display_mode mode;
> +	const struct drm_format_info *format;
> +	unsigned int pitch;
> +
> +	/* memory management */
> +	struct resource *mem;
> +	void __iomem *screen_base;
> +
> +	/* modesetting */
> +	struct drm_connector connector;
> +	struct drm_simple_display_pipe pipe;
> +};
> +
> +static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
> +{
> +	return container_of(dev, struct simplekms_device, dev);
> +}
> +
> +/*
> + *  Simplefb settings
> + */
> +
> +static struct drm_display_mode simplekms_mode(unsigned int width,
> +					      unsigned int height)
> +{
> +	struct drm_display_mode mode = { SIMPLEKMS_MODE(width, height) };
> +
> +	mode.clock = 60 /* Hz */ * mode.hdisplay * mode.vdisplay;
> +	drm_mode_set_name(&mode);
> +
> +	return mode;
> +}
> +
> +static int simplekms_device_init_fb(struct simplekms_device *sdev)
> +{
> +	int width, height, stride;
> +	const struct drm_format_info *format;
> +	struct drm_format_name_buf buf;
> +	struct drm_device *dev = &sdev->dev;
> +	struct platform_device *pdev = sdev->pdev;
> +	const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
> +
> +	if (pd) {
> +		width = simplefb_get_width_pd(dev, pd);
> +		if (width < 0)
> +			return width;
> +		height = simplefb_get_height_pd(dev, pd);
> +		if (height < 0)
> +			return height;
> +		stride = simplefb_get_stride_pd(dev, pd);
> +		if (stride < 0)
> +			return stride;
> +		format = simplefb_get_format_pd(dev, pd);
> +		if (IS_ERR(format))
> +			return PTR_ERR(format);
> +	} else {
> +		drm_err(dev, "no simplefb configuration found\n");
> +		return -ENODEV;
> +	}
> +
> +	sdev->mode = simplekms_mode(width, height);
> +	sdev->format = format;
> +	sdev->pitch = stride;
> +
> +	drm_dbg_kms(dev, "display mode={" DRM_MODE_FMT "}\n",
> +		    DRM_MODE_ARG(&sdev->mode));
> +	drm_dbg_kms(dev,
> +		    "framebuffer format=\"%s\", size=%dx%d, stride=%d byte\n",
> +		    drm_get_format_name(format->format, &buf), width,
> +		    height, stride);
> +
> +	return 0;
> +}
> +
> +/*
> + * Memory management
> + */
> +
> +static int simplekms_device_init_mm(struct simplekms_device *sdev)
> +{
> +	struct platform_device *pdev = sdev->pdev;
> +	struct resource *mem;
> +	void __iomem *screen_base;
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	if (!mem)
> +		return -EINVAL;
> +
> +	screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
> +				      resource_size(mem));
> +	if (!screen_base)
> +		return -ENOMEM;
> +
> +	sdev->mem = mem;
> +	sdev->screen_base = screen_base;
> +
> +	return 0;
> +}
> +
> +/*
> + * Modesetting
> + */
> +
> +/*
> + * Support all formats of simplefb and maybe more; in order
> + * of preference. The display's update function will do any
> + * conversion necessary.
> + *
> + * TODO: Add blit helpers for remaining formats and uncomment
> + *       constants.
> + */
> +static const uint32_t simplekms_formats[] = {
> +	DRM_FORMAT_XRGB8888,
> +	DRM_FORMAT_ARGB8888,
> +	DRM_FORMAT_RGB565,
> +	//DRM_FORMAT_XRGB1555,
> +	//DRM_FORMAT_ARGB1555,
> +	DRM_FORMAT_RGB888,
> +	//DRM_FORMAT_XRGB2101010,
> +	//DRM_FORMAT_ARGB2101010,
> +};
> +
> +static const uint64_t simplekms_format_modifiers[] = {
> +	DRM_FORMAT_MOD_LINEAR,
> +	DRM_FORMAT_MOD_INVALID
> +};
> +
> +static int simplekms_connector_get_modes(struct drm_connector *connector)
> +{
> +	struct simplekms_device *sdev = simplekms_device_of_dev(connector->dev);
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(connector->dev, &sdev->mode);
> +	if (!mode)
> +                return 0;
> +
> +	if (mode->name[0] == '\0')
> +		drm_mode_set_name(mode);
> +
> +	mode->type |= DRM_MODE_TYPE_PREFERRED;
> +	drm_mode_probed_add(connector, mode);
> +
> +	if (mode->width_mm)
> +                connector->display_info.width_mm = mode->width_mm;
> +	if (mode->height_mm)
> +                connector->display_info.height_mm = mode->height_mm;
> +
> +        return 1;
> +}
> +
> +static const struct drm_connector_helper_funcs simplekms_connector_helper_funcs = {
> +	.get_modes = simplekms_connector_get_modes,
> +};
> +
> +static const struct drm_connector_funcs simplekms_connector_funcs = {
> +	.reset = drm_atomic_helper_connector_reset,
> +	.fill_modes = drm_helper_probe_single_connector_modes,
> +	.destroy = drm_connector_cleanup,
> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
> +};
> +
> +static int
> +simplekms_simple_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
> +				    const struct drm_display_mode *mode)
> +{
> +	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
> +
> +	if (mode->hdisplay != sdev->mode.hdisplay &&
> +	    mode->vdisplay != sdev->mode.vdisplay)
> +		return MODE_ONE_SIZE;

I'd simplify this to an || and delete the two below. Userspace wont care
anyway.

> +	else if (mode->hdisplay != sdev->mode.hdisplay)
> +		return MODE_ONE_WIDTH;
> +	else if (mode->vdisplay != sdev->mode.vdisplay)
> +		return MODE_ONE_HEIGHT;
> +
> +	return MODE_OK;
> +}
> +
> +static void
> +simplekms_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
> +				struct drm_crtc_state *crtc_state,
> +				struct drm_plane_state *plane_state)
> +{
> +	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
> +	struct drm_plane_state *state = pipe->plane.state;
> +	struct drm_framebuffer *fb = state->fb;
> +	void *vmap;
> +
> +	vmap = drm_gem_shmem_vmap(fb->obj[0]);
> +	if (!vmap)
> +		return;
> +
> +	drm_fb_blit_dstclip(sdev->screen_base, sdev->pitch,
> +			    sdev->format->format, vmap, fb);
> +
> +	drm_gem_shmem_vunmap(fb->obj[0], vmap);
> +}
> +
> +static void
> +simplekms_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
> +				struct drm_plane_state *old_plane_state)
> +{
> +	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
> +	struct drm_plane_state *state = pipe->plane.state;
> +	struct drm_framebuffer *fb = state->fb;
> +	struct drm_rect clip;
> +	void *vmap;
> +
> +	if (!drm_atomic_helper_damage_merged(old_plane_state, state, &clip))
> +		return;
> +
> +	vmap = drm_gem_shmem_vmap(fb->obj[0]);
> +	if (!vmap)
> +		return;
> +
> +	drm_fb_blit_rect_dstclip(sdev->screen_base, sdev->pitch,
> +				 sdev->format->format, vmap, fb, &clip);
> +
> +	drm_gem_shmem_vunmap(fb->obj[0], vmap);
> +}
> +
> +static const struct drm_simple_display_pipe_funcs
> +simplekms_simple_display_pipe_funcs = {
> +	.mode_valid = simplekms_simple_display_pipe_mode_valid,
> +	.enable = simplekms_simple_display_pipe_enable,

A disable hook that clears it all to black would be nice.

> +	.update = simplekms_simple_display_pipe_update,
> +	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
> +};
> +
> +static const struct drm_mode_config_funcs simplekms_mode_config_funcs = {
> +	.fb_create = drm_gem_fb_create_with_dirty,
> +	.atomic_check = drm_atomic_helper_check,
> +	.atomic_commit = drm_atomic_helper_commit,
> +};
> +
> +static int simplekms_device_init_modeset(struct simplekms_device *sdev)
> +{
> +	struct drm_device *dev = &sdev->dev;
> +	struct drm_display_mode *mode = &sdev->mode;
> +	struct drm_connector *connector = &sdev->connector;
> +	struct drm_simple_display_pipe *pipe = &sdev->pipe;
> +	int ret;
> +
> +	ret = drmm_mode_config_init(dev);
> +	if (ret)
> +		return ret;
> +
> +	dev->mode_config.min_width = mode->hdisplay;
> +	dev->mode_config.max_width = mode->hdisplay;
> +	dev->mode_config.min_height = mode->vdisplay;
> +	dev->mode_config.max_height = mode->vdisplay;
> +	dev->mode_config.prefer_shadow = true;
> +	dev->mode_config.preferred_depth = sdev->format->cpp[0] * 8;
> +	dev->mode_config.funcs = &simplekms_mode_config_funcs;
> +
> +	drm_connector_helper_add(connector, &simplekms_connector_helper_funcs);
> +	ret = drm_connector_init(dev, connector, &simplekms_connector_funcs,
> +				 DRM_MODE_CONNECTOR_Unknown);

Quite bad amounts of boilerplate for the connector, but I guess everyone
else with a simple output that's totally fixed just uses drm_panel. Which
doesn't really fit here (but most likely would reduce code a bunch I
suspect).

> +	if (ret)
> +		return ret;
> +
> +	ret = drm_simple_display_pipe_init(dev, pipe,
> +					   &simplekms_simple_display_pipe_funcs,
> +					   simplekms_formats,

I don't think this works, you need to allocate a custom format list with 3
entries:
- actual format of the underlying fb, so we avoid conversion if possible
- the xrgb/argb8888 fallbacks as usual

Announcing all of them userspace might pick something that you can't do.

> +					   ARRAY_SIZE(simplekms_formats),
> +					   simplekms_format_modifiers,
> +					   connector);
> +	if (ret)
> +		return ret;
> +
> +	drm_mode_config_reset(dev);

This breaks fastboot. I think ideally we'd have the state represent
everything is on, and allocate an fb + buffer with the current contents of
the framebuffer. Since we can allocate an fb that matches this shouldn't
be a problem, just a raw memcpy_fromio should do the job.

Having a nice new simplekms drm driver and then losing fastboot feels like
slightly off tradeoff.

Maybe in a follow-up patch, but before fbcon setup? Since ideally fbcon
also takes over the already existing framebuffer we allocated, so that as
long as nothing clears the fb (i.e. fbcon is quiet) we'd preserve the
original framebuffer throughout the boot-up sequence.

> +
> +	return 0;
> +}
> +
> +/*
> + * Init / Cleanup
> + */
> +
> +static void simplekms_device_cleanup(struct simplekms_device* sdev)
> +{
> +	struct drm_device *dev = &sdev->dev;
> +
> +	drm_dev_unregister(dev);

I'd inline this, I guess there was once more before you switched
everything over to devm_

> +}
> +
> +static struct simplekms_device *
> +simplekms_device_create(struct drm_driver *drv, struct platform_device *pdev)
> +{
> +	struct simplekms_device *sdev;
> +	int ret;
> +
> +	sdev = devm_drm_dev_alloc(&pdev->dev, drv, struct simplekms_device,
> +				  dev);
> +	if (IS_ERR(sdev))
> +		return ERR_CAST(sdev);
> +	sdev->pdev = pdev;
> +
> +	ret = simplekms_device_init_fb(sdev);
> +	if (ret)
> +		return ERR_PTR(ret);
> +	ret = simplekms_device_init_mm(sdev);
> +	if (ret)
> +		return ERR_PTR(ret);
> +	ret = simplekms_device_init_modeset(sdev);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return sdev;
> +}
> +
> +/*
> + * DRM driver
> + */
> +
> +DEFINE_DRM_GEM_FOPS(simplekms_fops);
> +
> +static struct drm_driver simplekms_driver = {
> +	DRM_GEM_SHMEM_DRIVER_OPS,
> +	.name			= DRIVER_NAME,
> +	.desc			= DRIVER_DESC,
> +	.date			= DRIVER_DATE,
> +	.major			= DRIVER_MAJOR,
> +	.minor			= DRIVER_MINOR,
> +	.driver_features	= DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
> +	.fops			= &simplekms_fops,
> +};
> +
> +/*
> + * Platform driver
> + */
> +
> +static int simplekms_probe(struct platform_device *pdev)
> +{
> +	struct simplekms_device *sdev;
> +	struct drm_device *dev;
> +	int ret;
> +
> +	sdev = simplekms_device_create(&simplekms_driver, pdev);
> +	if (IS_ERR(sdev))
> +		return PTR_ERR(sdev);
> +	dev = &sdev->dev;
> +
> +	ret = drm_dev_register(dev, 0);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static int simplekms_remove(struct platform_device *pdev)
> +{
> +	struct simplekms_device *sdev = platform_get_drvdata(pdev);
> +
> +	simplekms_device_cleanup(sdev);

If you add the ->disable hook then a comment here that we don't want to
shut down to allow fastboot would be nice.

> +
> +	return 0;
> +}
> +
> +static struct platform_driver simplekms_platform_driver = {
> +	.driver = {
> +		.name = "simple-framebuffer", /* connect to sysfb */
> +	},
> +	.probe = simplekms_probe,
> +	.remove = simplekms_remove,
> +};
> +
> +module_platform_driver(simplekms_platform_driver);
> +
> +MODULE_DESCRIPTION(DRIVER_DESC);
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.27.0
> 

Cheers, Daniel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 3/9] drm: Add simplekms driver

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 20813 bytes --]

Hi Daniel

Am 29.06.20 um 11:06 schrieb Daniel Vetter:
> On Thu, Jun 25, 2020 at 02:00:05PM +0200, Thomas Zimmermann wrote:
>> The simplekms driver is a DRM driver for simplefb framebuffers as
>> provided by the kernel's boot code. This driver enables basic
>> graphical output on many different graphics devices that are provided
>> by the platform (e.g., EFI, VESA, embedded framebuffers).
>>
>> With the kernel's simplefb infrastructure, the kernel receives a
>> pre-configured framebuffer from the system (i.e., firmware, boot
>> loader). It creates a platform device to which simplekms attaches.
>> The system's framebuffer consists of a memory range, size and format.
>> Based on these values, simplekms creates a DRM devices. No actual
>> modesetting is possible.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> ---
>>  MAINTAINERS                      |   6 +
>>  drivers/gpu/drm/tiny/Kconfig     |  16 +
>>  drivers/gpu/drm/tiny/Makefile    |   1 +
>>  drivers/gpu/drm/tiny/simplekms.c | 495 +++++++++++++++++++++++++++++++
>>  4 files changed, 518 insertions(+)
>>  create mode 100644 drivers/gpu/drm/tiny/simplekms.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index f17d99164a77..ac517dc8d05d 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -5505,6 +5505,12 @@ S:	Orphan / Obsolete
>>  F:	drivers/gpu/drm/savage/
>>  F:	include/uapi/drm/savage_drm.h
>>  
>> +DRM DRIVER FOR SIMPLE FRAMEBUFFERS
>> +M:	Thomas Zimmermann <tzimmermann@suse.de>
>> +S:	Maintained
>> +T:	git git://anongit.freedesktop.org/drm/drm-misc
>> +F:	drivers/gpu/drm/tiny/simplekms.c
>> +
>>  DRM DRIVER FOR SIS VIDEO CARDS
>>  S:	Orphan / Obsolete
>>  F:	drivers/gpu/drm/sis/
>> diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
>> index 2b6414f0fa75..50dbde8bdcb2 100644
>> --- a/drivers/gpu/drm/tiny/Kconfig
>> +++ b/drivers/gpu/drm/tiny/Kconfig
>> @@ -28,6 +28,22 @@ config DRM_GM12U320
>>  	 This is a KMS driver for projectors which use the GM12U320 chipset
>>  	 for video transfer over USB2/3, such as the Acer C120 mini projector.
>>  
>> +config DRM_SIMPLEKMS
>> +	tristate "Simple framebuffer driver"
>> +	depends on DRM
>> +	select DRM_GEM_SHMEM_HELPER
>> +	select DRM_KMS_HELPER
>> +	help
>> +	  DRM driver for simple platform-provided framebuffers.
>> +
>> +	  This driver assumes that the display hardware has been initialized
>> +	  by the firmware or bootloader before the kernel boots. Scanout
>> +	  buffer, size, and display format must be provided via device tree,
>> +	  UEFI, VESA, etc.
>> +
>> +	  On x86 and compatible, you should also select CONFIG_X86_SYSFB to
>> +	  use UEFI and VESA framebuffers.
>> +
>>  config TINYDRM_HX8357D
>>  	tristate "DRM support for HX8357D display panels"
>>  	depends on DRM && SPI
>> diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
>> index 6ae4e9e5a35f..e83fbbfa7344 100644
>> --- a/drivers/gpu/drm/tiny/Makefile
>> +++ b/drivers/gpu/drm/tiny/Makefile
>> @@ -2,6 +2,7 @@
>>  
>>  obj-$(CONFIG_DRM_CIRRUS_QEMU)		+= cirrus.o
>>  obj-$(CONFIG_DRM_GM12U320)		+= gm12u320.o
>> +obj-$(CONFIG_DRM_SIMPLEKMS)		+= simplekms.o
>>  obj-$(CONFIG_TINYDRM_HX8357D)		+= hx8357d.o
>>  obj-$(CONFIG_TINYDRM_ILI9225)		+= ili9225.o
>>  obj-$(CONFIG_TINYDRM_ILI9341)		+= ili9341.o
>> diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
>> new file mode 100644
>> index 000000000000..dc7cf3983945
>> --- /dev/null
>> +++ b/drivers/gpu/drm/tiny/simplekms.c
>> @@ -0,0 +1,495 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +
>> +#include <linux/platform_data/simplefb.h>
>> +#include <linux/platform_device.h>
>> +
>> +#include <drm/drm_atomic_state_helper.h>
>> +#include <drm/drm_connector.h>
>> +#include <drm/drm_damage_helper.h>
>> +#include <drm/drm_device.h>
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_format_helper.h>
>> +#include <drm/drm_gem_framebuffer_helper.h>
>> +#include <drm/drm_gem_shmem_helper.h>
>> +#include <drm/drm_managed.h>
>> +#include <drm/drm_modeset_helper_vtables.h>
>> +#include <drm/drm_probe_helper.h>
>> +#include <drm/drm_simple_kms_helper.h>
>> +
>> +#define DRIVER_NAME	"simplekms"
>> +#define DRIVER_DESC	"DRM driver for simple-framebuffer platform devices"
>> +#define DRIVER_DATE	"20200625"
>> +#define DRIVER_MAJOR	1
>> +#define DRIVER_MINOR	0
>> +
>> +/*
>> + * Assume a monitor resolution of 96 dpi to
>> + * get a somewhat reasonable screen size.
>> + */
>> +#define RES_MM(d)	\
>> +	(((d) * 254ul) / (96ul * 10ul))
>> +
>> +#define SIMPLEKMS_MODE(hd, vd)	\
>> +	DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
>> +
>> +/*
>> + * Helpers for simplefb
>> + */
>> +
>> +static int
>> +simplefb_get_validated_int(struct drm_device *dev, const char *name,
>> +			   uint32_t value)
>> +{
>> +	if (value > INT_MAX) {
>> +		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
>> +			name, value);
>> +		return -EINVAL;
>> +	}
>> +	return (int)value;
>> +}
>> +
>> +static int
>> +simplefb_get_validated_int0(struct drm_device *dev, const char *name,
>> +			    uint32_t value)
>> +{
>> +	if (!value) {
>> +		drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
>> +			name, value);
>> +		return -EINVAL;
>> +	}
>> +	return simplefb_get_validated_int(dev, name, value);
>> +}
>> +
>> +static const struct drm_format_info *
>> +simplefb_get_validated_format(struct drm_device *dev, const char *format_name)
>> +{
>> +	static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
>> +	const struct simplefb_format *fmt = formats;
>> +	const struct simplefb_format *end = fmt + ARRAY_SIZE(formats);
>> +
>> +	if (!format_name) {
>> +		drm_err(dev, "simplefb: missing framebuffer format\n");
>> +		return ERR_PTR(-EINVAL);
>> +	}
>> +
>> +	while (fmt < end) {
>> +		if (!strcmp(format_name, fmt->name))
>> +			return drm_format_info(fmt->fourcc);
>> +		++fmt;
>> +	}
>> +
>> +	drm_err(dev, "simplefb: unknown framebuffer format %s\n",
>> +		format_name);
>> +
>> +	return ERR_PTR(-EINVAL);
>> +}
>> +
>> +static int
>> +simplefb_get_width_pd(struct drm_device *dev,
>> +		      const struct simplefb_platform_data *pd)
>> +{
>> +	return simplefb_get_validated_int0(dev, "width", pd->width);
>> +}
>> +
>> +static int
>> +simplefb_get_height_pd(struct drm_device *dev,
>> +		       const struct simplefb_platform_data *pd)
>> +{
>> +	return simplefb_get_validated_int0(dev, "height", pd->height);
>> +}
>> +
>> +static int
>> +simplefb_get_stride_pd(struct drm_device *dev,
>> +		       const struct simplefb_platform_data *pd)
>> +{
>> +	return simplefb_get_validated_int(dev, "stride", pd->stride);
>> +}
>> +
>> +static const struct drm_format_info *
>> +simplefb_get_format_pd(struct drm_device *dev,
>> +		       const struct simplefb_platform_data *pd)
>> +{
>> +	return simplefb_get_validated_format(dev, pd->format);
>> +}
>> +
>> +/*
>> + * Simple Framebuffer device
>> + */
>> +
>> +struct simplekms_device {
>> +	struct drm_device dev;
>> +	struct platform_device *pdev;
>> +
>> +	/* simplefb settings */
>> +	struct drm_display_mode mode;
>> +	const struct drm_format_info *format;
>> +	unsigned int pitch;
>> +
>> +	/* memory management */
>> +	struct resource *mem;
>> +	void __iomem *screen_base;
>> +
>> +	/* modesetting */
>> +	struct drm_connector connector;
>> +	struct drm_simple_display_pipe pipe;
>> +};
>> +
>> +static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
>> +{
>> +	return container_of(dev, struct simplekms_device, dev);
>> +}
>> +
>> +/*
>> + *  Simplefb settings
>> + */
>> +
>> +static struct drm_display_mode simplekms_mode(unsigned int width,
>> +					      unsigned int height)
>> +{
>> +	struct drm_display_mode mode = { SIMPLEKMS_MODE(width, height) };
>> +
>> +	mode.clock = 60 /* Hz */ * mode.hdisplay * mode.vdisplay;
>> +	drm_mode_set_name(&mode);
>> +
>> +	return mode;
>> +}
>> +
>> +static int simplekms_device_init_fb(struct simplekms_device *sdev)
>> +{
>> +	int width, height, stride;
>> +	const struct drm_format_info *format;
>> +	struct drm_format_name_buf buf;
>> +	struct drm_device *dev = &sdev->dev;
>> +	struct platform_device *pdev = sdev->pdev;
>> +	const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
>> +
>> +	if (pd) {
>> +		width = simplefb_get_width_pd(dev, pd);
>> +		if (width < 0)
>> +			return width;
>> +		height = simplefb_get_height_pd(dev, pd);
>> +		if (height < 0)
>> +			return height;
>> +		stride = simplefb_get_stride_pd(dev, pd);
>> +		if (stride < 0)
>> +			return stride;
>> +		format = simplefb_get_format_pd(dev, pd);
>> +		if (IS_ERR(format))
>> +			return PTR_ERR(format);
>> +	} else {
>> +		drm_err(dev, "no simplefb configuration found\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	sdev->mode = simplekms_mode(width, height);
>> +	sdev->format = format;
>> +	sdev->pitch = stride;
>> +
>> +	drm_dbg_kms(dev, "display mode={" DRM_MODE_FMT "}\n",
>> +		    DRM_MODE_ARG(&sdev->mode));
>> +	drm_dbg_kms(dev,
>> +		    "framebuffer format=\"%s\", size=%dx%d, stride=%d byte\n",
>> +		    drm_get_format_name(format->format, &buf), width,
>> +		    height, stride);
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Memory management
>> + */
>> +
>> +static int simplekms_device_init_mm(struct simplekms_device *sdev)
>> +{
>> +	struct platform_device *pdev = sdev->pdev;
>> +	struct resource *mem;
>> +	void __iomem *screen_base;
>> +
>> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	if (!mem)
>> +		return -EINVAL;
>> +
>> +	screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
>> +				      resource_size(mem));
>> +	if (!screen_base)
>> +		return -ENOMEM;
>> +
>> +	sdev->mem = mem;
>> +	sdev->screen_base = screen_base;
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Modesetting
>> + */
>> +
>> +/*
>> + * Support all formats of simplefb and maybe more; in order
>> + * of preference. The display's update function will do any
>> + * conversion necessary.
>> + *
>> + * TODO: Add blit helpers for remaining formats and uncomment
>> + *       constants.
>> + */
>> +static const uint32_t simplekms_formats[] = {
>> +	DRM_FORMAT_XRGB8888,
>> +	DRM_FORMAT_ARGB8888,
>> +	DRM_FORMAT_RGB565,
>> +	//DRM_FORMAT_XRGB1555,
>> +	//DRM_FORMAT_ARGB1555,
>> +	DRM_FORMAT_RGB888,
>> +	//DRM_FORMAT_XRGB2101010,
>> +	//DRM_FORMAT_ARGB2101010,
>> +};
>> +
>> +static const uint64_t simplekms_format_modifiers[] = {
>> +	DRM_FORMAT_MOD_LINEAR,
>> +	DRM_FORMAT_MOD_INVALID
>> +};
>> +
>> +static int simplekms_connector_get_modes(struct drm_connector *connector)
>> +{
>> +	struct simplekms_device *sdev = simplekms_device_of_dev(connector->dev);
>> +	struct drm_display_mode *mode;
>> +
>> +	mode = drm_mode_duplicate(connector->dev, &sdev->mode);
>> +	if (!mode)
>> +                return 0;
>> +
>> +	if (mode->name[0] == '\0')
>> +		drm_mode_set_name(mode);
>> +
>> +	mode->type |= DRM_MODE_TYPE_PREFERRED;
>> +	drm_mode_probed_add(connector, mode);
>> +
>> +	if (mode->width_mm)
>> +                connector->display_info.width_mm = mode->width_mm;
>> +	if (mode->height_mm)
>> +                connector->display_info.height_mm = mode->height_mm;
>> +
>> +        return 1;
>> +}
>> +
>> +static const struct drm_connector_helper_funcs simplekms_connector_helper_funcs = {
>> +	.get_modes = simplekms_connector_get_modes,
>> +};
>> +
>> +static const struct drm_connector_funcs simplekms_connector_funcs = {
>> +	.reset = drm_atomic_helper_connector_reset,
>> +	.fill_modes = drm_helper_probe_single_connector_modes,
>> +	.destroy = drm_connector_cleanup,
>> +	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
>> +	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
>> +};
>> +
>> +static int
>> +simplekms_simple_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
>> +				    const struct drm_display_mode *mode)
>> +{
>> +	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
>> +
>> +	if (mode->hdisplay != sdev->mode.hdisplay &&
>> +	    mode->vdisplay != sdev->mode.vdisplay)
>> +		return MODE_ONE_SIZE;
> 
> I'd simplify this to an || and delete the two below. Userspace wont care
> anyway.
> 
>> +	else if (mode->hdisplay != sdev->mode.hdisplay)
>> +		return MODE_ONE_WIDTH;
>> +	else if (mode->vdisplay != sdev->mode.vdisplay)
>> +		return MODE_ONE_HEIGHT;
>> +
>> +	return MODE_OK;
>> +}
>> +
>> +static void
>> +simplekms_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
>> +				struct drm_crtc_state *crtc_state,
>> +				struct drm_plane_state *plane_state)
>> +{
>> +	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
>> +	struct drm_plane_state *state = pipe->plane.state;
>> +	struct drm_framebuffer *fb = state->fb;
>> +	void *vmap;
>> +
>> +	vmap = drm_gem_shmem_vmap(fb->obj[0]);
>> +	if (!vmap)
>> +		return;
>> +
>> +	drm_fb_blit_dstclip(sdev->screen_base, sdev->pitch,
>> +			    sdev->format->format, vmap, fb);
>> +
>> +	drm_gem_shmem_vunmap(fb->obj[0], vmap);
>> +}
>> +
>> +static void
>> +simplekms_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
>> +				struct drm_plane_state *old_plane_state)
>> +{
>> +	struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
>> +	struct drm_plane_state *state = pipe->plane.state;
>> +	struct drm_framebuffer *fb = state->fb;
>> +	struct drm_rect clip;
>> +	void *vmap;
>> +
>> +	if (!drm_atomic_helper_damage_merged(old_plane_state, state, &clip))
>> +		return;
>> +
>> +	vmap = drm_gem_shmem_vmap(fb->obj[0]);
>> +	if (!vmap)
>> +		return;
>> +
>> +	drm_fb_blit_rect_dstclip(sdev->screen_base, sdev->pitch,
>> +				 sdev->format->format, vmap, fb, &clip);
>> +
>> +	drm_gem_shmem_vunmap(fb->obj[0], vmap);
>> +}
>> +
>> +static const struct drm_simple_display_pipe_funcs
>> +simplekms_simple_display_pipe_funcs = {
>> +	.mode_valid = simplekms_simple_display_pipe_mode_valid,
>> +	.enable = simplekms_simple_display_pipe_enable,
> 
> A disable hook that clears it all to black would be nice.
> 
>> +	.update = simplekms_simple_display_pipe_update,
>> +	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
>> +};
>> +
>> +static const struct drm_mode_config_funcs simplekms_mode_config_funcs = {
>> +	.fb_create = drm_gem_fb_create_with_dirty,
>> +	.atomic_check = drm_atomic_helper_check,
>> +	.atomic_commit = drm_atomic_helper_commit,
>> +};
>> +
>> +static int simplekms_device_init_modeset(struct simplekms_device *sdev)
>> +{
>> +	struct drm_device *dev = &sdev->dev;
>> +	struct drm_display_mode *mode = &sdev->mode;
>> +	struct drm_connector *connector = &sdev->connector;
>> +	struct drm_simple_display_pipe *pipe = &sdev->pipe;
>> +	int ret;
>> +
>> +	ret = drmm_mode_config_init(dev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dev->mode_config.min_width = mode->hdisplay;
>> +	dev->mode_config.max_width = mode->hdisplay;
>> +	dev->mode_config.min_height = mode->vdisplay;
>> +	dev->mode_config.max_height = mode->vdisplay;
>> +	dev->mode_config.prefer_shadow = true;
>> +	dev->mode_config.preferred_depth = sdev->format->cpp[0] * 8;
>> +	dev->mode_config.funcs = &simplekms_mode_config_funcs;
>> +
>> +	drm_connector_helper_add(connector, &simplekms_connector_helper_funcs);
>> +	ret = drm_connector_init(dev, connector, &simplekms_connector_funcs,
>> +				 DRM_MODE_CONNECTOR_Unknown);
> 
> Quite bad amounts of boilerplate for the connector, but I guess everyone
> else with a simple output that's totally fixed just uses drm_panel. Which
> doesn't really fit here (but most likely would reduce code a bunch I
> suspect).
> 
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = drm_simple_display_pipe_init(dev, pipe,
>> +					   &simplekms_simple_display_pipe_funcs,
>> +					   simplekms_formats,
> 
> I don't think this works, you need to allocate a custom format list with 3
> entries:
> - actual format of the underlying fb, so we avoid conversion if possible
> - the xrgb/argb8888 fallbacks as usual
> 
> Announcing all of them userspace might pick something that you can't do.
> 
>> +					   ARRAY_SIZE(simplekms_formats),
>> +					   simplekms_format_modifiers,
>> +					   connector);
>> +	if (ret)
>> +		return ret;
>> +
>> +	drm_mode_config_reset(dev);
> 
> This breaks fastboot. I think ideally we'd have the state represent
> everything is on, and allocate an fb + buffer with the current contents of
> the framebuffer. Since we can allocate an fb that matches this shouldn't
> be a problem, just a raw memcpy_fromio should do the job.

I'm trying to wrap my head around how the fastboot setup is implemented.

Apparently, i915's fbdev code goes through the existing pipeline state
and fills the fb_info structure with compatible settings.

Where is the initial pipeline state created? If I write reset handlers
that initialize the pipeline to the simple-framebuffer's fixed state,
whould that be sufficient? A later stage could then do the equivalent of
intel_fbdev_init_bios().

The simple-kms helpers don't seem to support custom reset handlers or
atomic-state callbacks. I guess that would require and update as well?

Best regards
Thomas

> 
> Having a nice new simplekms drm driver and then losing fastboot feels like
> slightly off tradeoff.
> 
> Maybe in a follow-up patch, but before fbcon setup? Since ideally fbcon
> also takes over the already existing framebuffer we allocated, so that as
> long as nothing clears the fb (i.e. fbcon is quiet) we'd preserve the
> original framebuffer throughout the boot-up sequence.
> 
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Init / Cleanup
>> + */
>> +
>> +static void simplekms_device_cleanup(struct simplekms_device* sdev)
>> +{
>> +	struct drm_device *dev = &sdev->dev;
>> +
>> +	drm_dev_unregister(dev);
> 
> I'd inline this, I guess there was once more before you switched
> everything over to devm_
> 
>> +}
>> +
>> +static struct simplekms_device *
>> +simplekms_device_create(struct drm_driver *drv, struct platform_device *pdev)
>> +{
>> +	struct simplekms_device *sdev;
>> +	int ret;
>> +
>> +	sdev = devm_drm_dev_alloc(&pdev->dev, drv, struct simplekms_device,
>> +				  dev);
>> +	if (IS_ERR(sdev))
>> +		return ERR_CAST(sdev);
>> +	sdev->pdev = pdev;
>> +
>> +	ret = simplekms_device_init_fb(sdev);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +	ret = simplekms_device_init_mm(sdev);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +	ret = simplekms_device_init_modeset(sdev);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	return sdev;
>> +}
>> +
>> +/*
>> + * DRM driver
>> + */
>> +
>> +DEFINE_DRM_GEM_FOPS(simplekms_fops);
>> +
>> +static struct drm_driver simplekms_driver = {
>> +	DRM_GEM_SHMEM_DRIVER_OPS,
>> +	.name			= DRIVER_NAME,
>> +	.desc			= DRIVER_DESC,
>> +	.date			= DRIVER_DATE,
>> +	.major			= DRIVER_MAJOR,
>> +	.minor			= DRIVER_MINOR,
>> +	.driver_features	= DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
>> +	.fops			= &simplekms_fops,
>> +};
>> +
>> +/*
>> + * Platform driver
>> + */
>> +
>> +static int simplekms_probe(struct platform_device *pdev)
>> +{
>> +	struct simplekms_device *sdev;
>> +	struct drm_device *dev;
>> +	int ret;
>> +
>> +	sdev = simplekms_device_create(&simplekms_driver, pdev);
>> +	if (IS_ERR(sdev))
>> +		return PTR_ERR(sdev);
>> +	dev = &sdev->dev;
>> +
>> +	ret = drm_dev_register(dev, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int simplekms_remove(struct platform_device *pdev)
>> +{
>> +	struct simplekms_device *sdev = platform_get_drvdata(pdev);
>> +
>> +	simplekms_device_cleanup(sdev);
> 
> If you add the ->disable hook then a comment here that we don't want to
> shut down to allow fastboot would be nice.
> 
>> +
>> +	return 0;
>> +}
>> +
>> +static struct platform_driver simplekms_platform_driver = {
>> +	.driver = {
>> +		.name = "simple-framebuffer", /* connect to sysfb */
>> +	},
>> +	.probe = simplekms_probe,
>> +	.remove = simplekms_remove,
>> +};
>> +
>> +module_platform_driver(simplekms_platform_driver);
>> +
>> +MODULE_DESCRIPTION(DRIVER_DESC);
>> +MODULE_LICENSE("GPL v2");
>> -- 
>> 2.27.0
>>
> 
> Cheers, Daniel
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 3/9] drm: Add simplekms driver

[Maxime Ripard]

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Hi Thomas,

On Fri, Sep 25, 2020 at 05:01:23PM +0200, Thomas Zimmermann wrote:
> >> +					   ARRAY_SIZE(simplekms_formats),
> >> +					   simplekms_format_modifiers,
> >> +					   connector);
> >> +	if (ret)
> >> +		return ret;
> >> +
> >> +	drm_mode_config_reset(dev);
> > 
> > This breaks fastboot. I think ideally we'd have the state represent
> > everything is on, and allocate an fb + buffer with the current contents of
> > the framebuffer. Since we can allocate an fb that matches this shouldn't
> > be a problem, just a raw memcpy_fromio should do the job.
> 
> I'm trying to wrap my head around how the fastboot setup is implemented.
> 
> Apparently, i915's fbdev code goes through the existing pipeline state
> and fills the fb_info structure with compatible settings.
> 
> Where is the initial pipeline state created? If I write reset handlers
> that initialize the pipeline to the simple-framebuffer's fixed state,
> whould that be sufficient? A later stage could then do the equivalent of
> intel_fbdev_init_bios().
> 
> The simple-kms helpers don't seem to support custom reset handlers or
> atomic-state callbacks. I guess that would require and update as well?

You probably want to read the following :)

https://lore.kernel.org/dri-devel/CAKMK7uHtqHy_oz4W7F+hmp9iqp7W5Ra8CxPvJ=9BwmvfU-O0gg@mail.gmail.com/

It's been on my todo-list since, but I never got to work on it :/

Maxime

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Re: [PATCH 3/9] drm: Add simplekms driver

[Thomas Zimmermann]

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Hi

Am 25.09.20 um 17:14 schrieb Maxime Ripard:
> Hi Thomas,
> 
> On Fri, Sep 25, 2020 at 05:01:23PM +0200, Thomas Zimmermann wrote:
>>>> +					   ARRAY_SIZE(simplekms_formats),
>>>> +					   simplekms_format_modifiers,
>>>> +					   connector);
>>>> +	if (ret)
>>>> +		return ret;
>>>> +
>>>> +	drm_mode_config_reset(dev);
>>>
>>> This breaks fastboot. I think ideally we'd have the state represent
>>> everything is on, and allocate an fb + buffer with the current contents of
>>> the framebuffer. Since we can allocate an fb that matches this shouldn't
>>> be a problem, just a raw memcpy_fromio should do the job.
>>
>> I'm trying to wrap my head around how the fastboot setup is implemented.
>>
>> Apparently, i915's fbdev code goes through the existing pipeline state
>> and fills the fb_info structure with compatible settings.
>>
>> Where is the initial pipeline state created? If I write reset handlers
>> that initialize the pipeline to the simple-framebuffer's fixed state,
>> whould that be sufficient? A later stage could then do the equivalent of
>> intel_fbdev_init_bios().
>>
>> The simple-kms helpers don't seem to support custom reset handlers or
>> atomic-state callbacks. I guess that would require and update as well?
> 
> You probably want to read the following :)
> 
> https://lore.kernel.org/dri-devel/CAKMK7uHtqHy_oz4W7F+hmp9iqp7W5Ra8CxPvJ=9BwmvfU-O0gg@mail.gmail.com/
> 
> It's been on my todo-list since, but I never got to work on it :/

Thanks for the pointer. This looks like the optimal solution, although
overkill for this simple use case.

For now, I'll probably initialize the state during initialization. When
the readout helpers materialize, I'll convert the driver.

Best regards
Thomas

> 
> Maxime
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 3/9] drm: Add simplekms driver

[Thomas Zimmermann]

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Hi

Am 29.06.20 um 11:06 schrieb Daniel Vetter:
> 
>> +					   ARRAY_SIZE(simplekms_formats),
>> +					   simplekms_format_modifiers,
>> +					   connector);
>> +	if (ret)
>> +		return ret;
>> +
>> +	drm_mode_config_reset(dev);
> 
> This breaks fastboot. I think ideally we'd have the state represent
> everything is on, and allocate an fb + buffer with the current contents of
> the framebuffer. Since we can allocate an fb that matches this shouldn't
> be a problem, just a raw memcpy_fromio should do the job.
> 
> Having a nice new simplekms drm driver and then losing fastboot feels like
> slightly off tradeoff.
> 
> Maybe in a follow-up patch, but before fbcon setup? Since ideally fbcon
> also takes over the already existing framebuffer we allocated, so that as
> long as nothing clears the fb (i.e. fbcon is quiet) we'd preserve the
> original framebuffer throughout the boot-up sequence.

I recently looked at how to implement this and it seems fairly complicated.

What we want it to adopt the current mode config into fbcon (and 
probably other in-kernel clients). The kernel client code uses it's own 
file instance to allocate the framebuffer objects against. So we cannot 
read-out the framebuffer state here. We'd ideally do this in the fbdev code.

I read through the proposal for read-out helpers. i915 seems to have 
lots of special cases. Can we adopt a simplified version that is just 
good enough to get the initial state for fbdev?

Best regards
Thomas

> 
>> +
>> +	return 0;
>> +}
>> +
>> +/*
>> + * Init / Cleanup
>> + */
>> +
>> +static void simplekms_device_cleanup(struct simplekms_device* sdev)
>> +{
>> +	struct drm_device *dev = &sdev->dev;
>> +
>> +	drm_dev_unregister(dev);
> 
> I'd inline this, I guess there was once more before you switched
> everything over to devm_
> 
>> +}
>> +
>> +static struct simplekms_device *
>> +simplekms_device_create(struct drm_driver *drv, struct platform_device *pdev)
>> +{
>> +	struct simplekms_device *sdev;
>> +	int ret;
>> +
>> +	sdev = devm_drm_dev_alloc(&pdev->dev, drv, struct simplekms_device,
>> +				  dev);
>> +	if (IS_ERR(sdev))
>> +		return ERR_CAST(sdev);
>> +	sdev->pdev = pdev;
>> +
>> +	ret = simplekms_device_init_fb(sdev);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +	ret = simplekms_device_init_mm(sdev);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +	ret = simplekms_device_init_modeset(sdev);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	return sdev;
>> +}
>> +
>> +/*
>> + * DRM driver
>> + */
>> +
>> +DEFINE_DRM_GEM_FOPS(simplekms_fops);
>> +
>> +static struct drm_driver simplekms_driver = {
>> +	DRM_GEM_SHMEM_DRIVER_OPS,
>> +	.name			= DRIVER_NAME,
>> +	.desc			= DRIVER_DESC,
>> +	.date			= DRIVER_DATE,
>> +	.major			= DRIVER_MAJOR,
>> +	.minor			= DRIVER_MINOR,
>> +	.driver_features	= DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
>> +	.fops			= &simplekms_fops,
>> +};
>> +
>> +/*
>> + * Platform driver
>> + */
>> +
>> +static int simplekms_probe(struct platform_device *pdev)
>> +{
>> +	struct simplekms_device *sdev;
>> +	struct drm_device *dev;
>> +	int ret;
>> +
>> +	sdev = simplekms_device_create(&simplekms_driver, pdev);
>> +	if (IS_ERR(sdev))
>> +		return PTR_ERR(sdev);
>> +	dev = &sdev->dev;
>> +
>> +	ret = drm_dev_register(dev, 0);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int simplekms_remove(struct platform_device *pdev)
>> +{
>> +	struct simplekms_device *sdev = platform_get_drvdata(pdev);
>> +
>> +	simplekms_device_cleanup(sdev);
> 
> If you add the ->disable hook then a comment here that we don't want to
> shut down to allow fastboot would be nice.
> 
>> +
>> +	return 0;
>> +}
>> +
>> +static struct platform_driver simplekms_platform_driver = {
>> +	.driver = {
>> +		.name = "simple-framebuffer", /* connect to sysfb */
>> +	},
>> +	.probe = simplekms_probe,
>> +	.remove = simplekms_remove,
>> +};
>> +
>> +module_platform_driver(simplekms_platform_driver);
>> +
>> +MODULE_DESCRIPTION(DRIVER_DESC);
>> +MODULE_LICENSE("GPL v2");
>> -- 
>> 2.27.0
>>
> 
> Cheers, Daniel
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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[PATCH 4/9] drm/simplekms: Add fbdev emulation

[Thomas Zimmermann]

This displays a console on the simplefb framebuffer. The default
framebuffer format is being used.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/simplekms.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
index dc7cf3983945..ac2ebfcedd22 100644
--- a/drivers/gpu/drm/tiny/simplekms.c
+++ b/drivers/gpu/drm/tiny/simplekms.c
@@ -8,6 +8,7 @@
 #include <drm/drm_damage_helper.h>
 #include <drm/drm_device.h>
 #include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
 #include <drm/drm_format_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_gem_shmem_helper.h>
@@ -469,6 +470,8 @@ static int simplekms_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	drm_fbdev_generic_setup(dev, 0);
+
 	return 0;
 }
 
-- 
2.27.0

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Re: [PATCH 4/9] drm/simplekms: Add fbdev emulation

[Daniel Vetter]

On Thu, Jun 25, 2020 at 02:00:06PM +0200, Thomas Zimmermann wrote:
> This displays a console on the simplefb framebuffer. The default
> framebuffer format is being used.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/tiny/simplekms.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
> index dc7cf3983945..ac2ebfcedd22 100644
> --- a/drivers/gpu/drm/tiny/simplekms.c
> +++ b/drivers/gpu/drm/tiny/simplekms.c
> @@ -8,6 +8,7 @@
>  #include <drm/drm_damage_helper.h>
>  #include <drm/drm_device.h>
>  #include <drm/drm_drv.h>
> +#include <drm/drm_fb_helper.h>
>  #include <drm/drm_format_helper.h>
>  #include <drm/drm_gem_framebuffer_helper.h>
>  #include <drm/drm_gem_shmem_helper.h>
> @@ -469,6 +470,8 @@ static int simplekms_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	drm_fbdev_generic_setup(dev, 0);

I think for the fastboot stuff what we could do is improve the generic
fbdev code with essentially what intel_fbdev_init_bios does. Well actually
just shovel that code into the helpers maybe, the other code to pick
initial configs for fastboot has been moved already too.

Otherwise lgtm ofc.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> +
>  	return 0;
>  }
>  
> -- 
> 2.27.0
> 

-- 
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Software Engineer, Intel Corporation
http://blog.ffwll.ch
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[PATCH 5/9] drm/simplekms: Initialize framebuffer data from device-tree node

[Thomas Zimmermann]

A firmware framebuffer might also be specified via device-tree files. If
no device platform data is given, try the DT device node.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/simplekms.c | 84 ++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)

diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
index ac2ebfcedd22..87636307aa4f 100644
--- a/drivers/gpu/drm/tiny/simplekms.c
+++ b/drivers/gpu/drm/tiny/simplekms.c
@@ -113,6 +113,76 @@ simplefb_get_format_pd(struct drm_device *dev,
 	return simplefb_get_validated_format(dev, pd->format);
 }
 
+static int
+simplefb_read_u32_of(struct drm_device *dev, struct device_node *of_node,
+		     const char* name, u32 *value)
+{
+	int ret = of_property_read_u32(of_node, name, value);
+	if (ret)
+		drm_err(dev, "simplefb: can't parse framebuffer %s: error %d\n",
+			name, ret);
+	return ret;
+}
+
+static int
+simplefb_read_string_of(struct drm_device *dev, struct device_node *of_node,
+			const char* name, const char **value)
+{
+	int ret = of_property_read_string(of_node, name, value);
+	if (ret)
+		drm_err(dev, "simplefb: can't parse framebuffer %s: error %d\n",
+			name, ret);
+	return ret;
+}
+
+static int
+simplefb_get_width_of(struct drm_device *dev, struct device_node *of_node)
+{
+	int ret;
+	u32 width;
+
+	ret = simplefb_read_u32_of(dev, of_node, "width", &width);
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int0(dev, "width", width);
+}
+
+static int
+simplefb_get_height_of(struct drm_device *dev, struct device_node *of_node)
+{
+	int ret;
+	u32 height;
+
+	ret = simplefb_read_u32_of(dev, of_node, "height", &height);
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int0(dev, "height", height);
+}
+
+static int
+simplefb_get_stride_of(struct drm_device *dev, struct device_node *of_node)
+{
+	int ret;
+	u32 stride;
+
+	ret = simplefb_read_u32_of(dev, of_node, "stride", &stride);
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int(dev, "stride", stride);
+}
+
+static const struct drm_format_info *
+simplefb_get_format_of(struct drm_device *dev, struct device_node *of_node)
+{
+	int ret;
+	const char *format;
+
+	ret = simplefb_read_string_of(dev, of_node, "format", &format);
+	if (ret)
+		return ERR_PTR(ret);
+	return simplefb_get_validated_format(dev, format);
+}
+
 /*
  * Simple Framebuffer device
  */
@@ -163,6 +233,7 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
 	struct drm_device *dev = &sdev->dev;
 	struct platform_device *pdev = sdev->pdev;
 	const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
+	struct device_node *of_node = pdev->dev.of_node;
 
 	if (pd) {
 		width = simplefb_get_width_pd(dev, pd);
@@ -177,6 +248,19 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
 		format = simplefb_get_format_pd(dev, pd);
 		if (IS_ERR(format))
 			return PTR_ERR(format);
+	} else if (of_node) {
+		width = simplefb_get_width_of(dev, of_node);
+		if (width < 0)
+			return width;
+		height = simplefb_get_height_of(dev, of_node);
+		if (height < 0)
+			return height;
+		stride = simplefb_get_stride_of(dev, of_node);
+		if (stride < 0)
+			return stride;
+		format = simplefb_get_format_of(dev, of_node);
+		if (IS_ERR(format))
+			return PTR_ERR(format);
 	} else {
 		drm_err(dev, "no simplefb configuration found\n");
 		return -ENODEV;
-- 
2.27.0

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Re: [PATCH 5/9] drm/simplekms: Initialize framebuffer data from device-tree node

[Rob Herring]

On Thu, Jun 25, 2020 at 6:00 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
> A firmware framebuffer might also be specified via device-tree files. If
> no device platform data is given, try the DT device node.

You are missing a DT match table for driver matching and module
loading (if a module is supported).

>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/tiny/simplekms.c | 84 ++++++++++++++++++++++++++++++++
>  1 file changed, 84 insertions(+)
>
> diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
> index ac2ebfcedd22..87636307aa4f 100644
> --- a/drivers/gpu/drm/tiny/simplekms.c
> +++ b/drivers/gpu/drm/tiny/simplekms.c
> @@ -113,6 +113,76 @@ simplefb_get_format_pd(struct drm_device *dev,
>         return simplefb_get_validated_format(dev, pd->format);
>  }
>
> +static int
> +simplefb_read_u32_of(struct drm_device *dev, struct device_node *of_node,
> +                    const char* name, u32 *value)
> +{
> +       int ret = of_property_read_u32(of_node, name, value);
> +       if (ret)
> +               drm_err(dev, "simplefb: can't parse framebuffer %s: error %d\n",
> +                       name, ret);
> +       return ret;
> +}
> +
> +static int
> +simplefb_read_string_of(struct drm_device *dev, struct device_node *of_node,
> +                       const char* name, const char **value)
> +{
> +       int ret = of_property_read_string(of_node, name, value);
> +       if (ret)
> +               drm_err(dev, "simplefb: can't parse framebuffer %s: error %d\n",
> +                       name, ret);
> +       return ret;
> +}
> +
> +static int
> +simplefb_get_width_of(struct drm_device *dev, struct device_node *of_node)
> +{
> +       int ret;
> +       u32 width;
> +
> +       ret = simplefb_read_u32_of(dev, of_node, "width", &width);
> +       if (ret)
> +               return ret;
> +       return simplefb_get_validated_int0(dev, "width", width);
> +}
> +
> +static int
> +simplefb_get_height_of(struct drm_device *dev, struct device_node *of_node)
> +{
> +       int ret;
> +       u32 height;
> +
> +       ret = simplefb_read_u32_of(dev, of_node, "height", &height);
> +       if (ret)
> +               return ret;
> +       return simplefb_get_validated_int0(dev, "height", height);
> +}
> +
> +static int
> +simplefb_get_stride_of(struct drm_device *dev, struct device_node *of_node)
> +{
> +       int ret;
> +       u32 stride;
> +
> +       ret = simplefb_read_u32_of(dev, of_node, "stride", &stride);
> +       if (ret)
> +               return ret;
> +       return simplefb_get_validated_int(dev, "stride", stride);
> +}
> +
> +static const struct drm_format_info *
> +simplefb_get_format_of(struct drm_device *dev, struct device_node *of_node)
> +{
> +       int ret;
> +       const char *format;
> +
> +       ret = simplefb_read_string_of(dev, of_node, "format", &format);
> +       if (ret)
> +               return ERR_PTR(ret);
> +       return simplefb_get_validated_format(dev, format);
> +}
> +
>  /*
>   * Simple Framebuffer device
>   */
> @@ -163,6 +233,7 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
>         struct drm_device *dev = &sdev->dev;
>         struct platform_device *pdev = sdev->pdev;
>         const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
> +       struct device_node *of_node = pdev->dev.of_node;
>
>         if (pd) {
>                 width = simplefb_get_width_pd(dev, pd);
> @@ -177,6 +248,19 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
>                 format = simplefb_get_format_pd(dev, pd);
>                 if (IS_ERR(format))
>                         return PTR_ERR(format);
> +       } else if (of_node) {
> +               width = simplefb_get_width_of(dev, of_node);
> +               if (width < 0)
> +                       return width;
> +               height = simplefb_get_height_of(dev, of_node);
> +               if (height < 0)
> +                       return height;
> +               stride = simplefb_get_stride_of(dev, of_node);
> +               if (stride < 0)
> +                       return stride;
> +               format = simplefb_get_format_of(dev, of_node);
> +               if (IS_ERR(format))
> +                       return PTR_ERR(format);
>         } else {
>                 drm_err(dev, "no simplefb configuration found\n");
>                 return -ENODEV;
> --
> 2.27.0
>
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[PATCH 6/9] drm/simplekms: Acquire clocks from DT device node

[Thomas Zimmermann]

Make sure required hardware clocks are enabled while the firmware
framebuffer is in use.

The basic code has been taken from the simplefb driver and adapted
to DRM. Clocks are released automatically via devres helpers.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/simplekms.c | 108 +++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)

diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
index 87636307aa4f..aca186decb48 100644
--- a/drivers/gpu/drm/tiny/simplekms.c
+++ b/drivers/gpu/drm/tiny/simplekms.c
@@ -1,5 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
+#include <linux/clk.h>
+#include <linux/of_clk.h>
 #include <linux/platform_data/simplefb.h>
 #include <linux/platform_device.h>
 
@@ -191,6 +193,12 @@ struct simplekms_device {
 	struct drm_device dev;
 	struct platform_device *pdev;
 
+	/* clocks */
+#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
+	unsigned int clk_count;
+	struct clk **clks;
+#endif
+
 	/* simplefb settings */
 	struct drm_display_mode mode;
 	const struct drm_format_info *format;
@@ -210,6 +218,103 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
 	return container_of(dev, struct simplekms_device, dev);
 }
 
+/*
+ * Hardware
+ */
+
+#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
+/*
+ * Clock handling code.
+ *
+ * Here we handle the clocks property of our "simple-framebuffer" dt node.
+ * This is necessary so that we can make sure that any clocks needed by
+ * the display engine that the bootloader set up for us (and for which it
+ * provided a simplefb dt node), stay up, for the life of the simplefb
+ * driver.
+ *
+ * When the driver unloads, we cleanly disable, and then release the clocks.
+ *
+ * We only complain about errors here, no action is taken as the most likely
+ * error can only happen due to a mismatch between the bootloader which set
+ * up simplefb, and the clock definitions in the device tree. Chances are
+ * that there are no adverse effects, and if there are, a clean teardown of
+ * the fb probe will not help us much either. So just complain and carry on,
+ * and hope that the user actually gets a working fb at the end of things.
+ */
+
+static void simplekms_device_release_clocks(void *res)
+{
+	struct simplekms_device *sdev = simplekms_device_of_dev(res);
+	unsigned int i;
+
+	for (i = 0; i < sdev->clk_count; ++i) {
+		if (sdev->clks[i]) {
+			clk_disable_unprepare(sdev->clks[i]);
+			clk_put(sdev->clks[i]);
+		}
+	}
+}
+
+static int simplekms_device_init_clocks(struct simplekms_device *sdev)
+{
+	struct drm_device *dev = &sdev->dev;
+	struct platform_device *pdev = sdev->pdev;
+	struct device_node *of_node = pdev->dev.of_node;
+	struct clk *clock;
+	unsigned int i;
+	int ret;
+
+	if (dev_get_platdata(&pdev->dev) || !of_node)
+		return 0;
+
+	sdev->clk_count = of_clk_get_parent_count(of_node);
+	if (!sdev->clk_count)
+		return 0;
+
+	sdev->clks = drmm_kzalloc(dev, sdev->clk_count * sizeof(sdev->clks[0]),
+				  GFP_KERNEL);
+	if (!sdev->clks)
+		return -ENOMEM;
+
+	for (i = 0; i < sdev->clk_count; ++i) {
+		clock = of_clk_get(of_node, i);
+		if (IS_ERR(clock)) {
+			ret = PTR_ERR(clock);
+			if (ret == -EPROBE_DEFER)
+				goto err;
+			drm_err(dev, "clock %u not found: %d\n", i, ret);
+			continue;
+		}
+		ret = clk_prepare_enable(clock);
+		if (ret) {
+			drm_err(dev, "failed to enable clock %u: %d\n",
+				i, ret);
+			clk_put(clock);
+		}
+		sdev->clks[i] = clock;
+	}
+
+	return devm_add_action_or_reset(&pdev->dev,
+					simplekms_device_release_clocks,
+					sdev);
+
+err:
+	while (i) {
+		--i;
+		if (sdev->clks[i]) {
+			clk_disable_unprepare(sdev->clks[i]);
+			clk_put(sdev->clks[i]);
+		}
+	}
+	return ret;
+}
+#else
+static int simplekms_device_init_clocks(struct simplekms_device *sdev)
+{
+	return 0;
+}
+#endif
+
 /*
  *  Simplefb settings
  */
@@ -505,6 +610,9 @@ simplekms_device_create(struct drm_driver *drv, struct platform_device *pdev)
 		return ERR_CAST(sdev);
 	sdev->pdev = pdev;
 
+	ret = simplekms_device_init_clocks(sdev);
+	if (ret)
+		return ERR_PTR(ret);
 	ret = simplekms_device_init_fb(sdev);
 	if (ret)
 		return ERR_PTR(ret);
-- 
2.27.0

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Re: [PATCH 6/9] drm/simplekms: Acquire clocks from DT device node

[Geert Uytterhoeven]

Hi Thomas,

On Thu, Jun 25, 2020 at 2:00 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> Make sure required hardware clocks are enabled while the firmware
> framebuffer is in use.
>
> The basic code has been taken from the simplefb driver and adapted
> to DRM. Clocks are released automatically via devres helpers.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Thanks for your patch!

> --- a/drivers/gpu/drm/tiny/simplekms.c
> +++ b/drivers/gpu/drm/tiny/simplekms.c

> @@ -210,6 +218,103 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
>         return container_of(dev, struct simplekms_device, dev);
>  }
>
> +/*
> + * Hardware
> + */
> +
> +#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
> +/*
> + * Clock handling code.
> + *
> + * Here we handle the clocks property of our "simple-framebuffer" dt node.
> + * This is necessary so that we can make sure that any clocks needed by
> + * the display engine that the bootloader set up for us (and for which it
> + * provided a simplefb dt node), stay up, for the life of the simplefb
> + * driver.
> + *
> + * When the driver unloads, we cleanly disable, and then release the clocks.
> + *
> + * We only complain about errors here, no action is taken as the most likely
> + * error can only happen due to a mismatch between the bootloader which set
> + * up simplefb, and the clock definitions in the device tree. Chances are
> + * that there are no adverse effects, and if there are, a clean teardown of
> + * the fb probe will not help us much either. So just complain and carry on,
> + * and hope that the user actually gets a working fb at the end of things.
> + */
> +
> +static void simplekms_device_release_clocks(void *res)
> +{
> +       struct simplekms_device *sdev = simplekms_device_of_dev(res);
> +       unsigned int i;
> +
> +       for (i = 0; i < sdev->clk_count; ++i) {
> +               if (sdev->clks[i]) {
> +                       clk_disable_unprepare(sdev->clks[i]);
> +                       clk_put(sdev->clks[i]);
> +               }
> +       }
> +}
> +
> +static int simplekms_device_init_clocks(struct simplekms_device *sdev)
> +{
> +       struct drm_device *dev = &sdev->dev;
> +       struct platform_device *pdev = sdev->pdev;
> +       struct device_node *of_node = pdev->dev.of_node;
> +       struct clk *clock;
> +       unsigned int i;
> +       int ret;
> +
> +       if (dev_get_platdata(&pdev->dev) || !of_node)
> +               return 0;
> +
> +       sdev->clk_count = of_clk_get_parent_count(of_node);
> +       if (!sdev->clk_count)
> +               return 0;
> +
> +       sdev->clks = drmm_kzalloc(dev, sdev->clk_count * sizeof(sdev->clks[0]),
> +                                 GFP_KERNEL);
> +       if (!sdev->clks)
> +               return -ENOMEM;
> +
> +       for (i = 0; i < sdev->clk_count; ++i) {
> +               clock = of_clk_get(of_node, i);

clk_bulk_get_all()?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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Re: [PATCH 6/9] drm/simplekms: Acquire clocks from DT device node

[Daniel Vetter]

On Thu, Jun 25, 2020 at 03:34:05PM +0200, Geert Uytterhoeven wrote:
> Hi Thomas,
> 
> On Thu, Jun 25, 2020 at 2:00 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> > Make sure required hardware clocks are enabled while the firmware
> > framebuffer is in use.
> >
> > The basic code has been taken from the simplefb driver and adapted
> > to DRM. Clocks are released automatically via devres helpers.
> >
> > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> Thanks for your patch!
> 
> > --- a/drivers/gpu/drm/tiny/simplekms.c
> > +++ b/drivers/gpu/drm/tiny/simplekms.c
> 
> > @@ -210,6 +218,103 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
> >         return container_of(dev, struct simplekms_device, dev);
> >  }
> >
> > +/*
> > + * Hardware
> > + */
> > +
> > +#if defined CONFIG_OF && defined CONFIG_COMMON_CLK
> > +/*
> > + * Clock handling code.
> > + *
> > + * Here we handle the clocks property of our "simple-framebuffer" dt node.
> > + * This is necessary so that we can make sure that any clocks needed by
> > + * the display engine that the bootloader set up for us (and for which it
> > + * provided a simplefb dt node), stay up, for the life of the simplefb
> > + * driver.
> > + *
> > + * When the driver unloads, we cleanly disable, and then release the clocks.
> > + *
> > + * We only complain about errors here, no action is taken as the most likely
> > + * error can only happen due to a mismatch between the bootloader which set
> > + * up simplefb, and the clock definitions in the device tree. Chances are
> > + * that there are no adverse effects, and if there are, a clean teardown of
> > + * the fb probe will not help us much either. So just complain and carry on,
> > + * and hope that the user actually gets a working fb at the end of things.
> > + */
> > +
> > +static void simplekms_device_release_clocks(void *res)
> > +{
> > +       struct simplekms_device *sdev = simplekms_device_of_dev(res);
> > +       unsigned int i;
> > +
> > +       for (i = 0; i < sdev->clk_count; ++i) {
> > +               if (sdev->clks[i]) {
> > +                       clk_disable_unprepare(sdev->clks[i]);
> > +                       clk_put(sdev->clks[i]);
> > +               }
> > +       }
> > +}
> > +
> > +static int simplekms_device_init_clocks(struct simplekms_device *sdev)
> > +{
> > +       struct drm_device *dev = &sdev->dev;
> > +       struct platform_device *pdev = sdev->pdev;
> > +       struct device_node *of_node = pdev->dev.of_node;
> > +       struct clk *clock;
> > +       unsigned int i;
> > +       int ret;
> > +
> > +       if (dev_get_platdata(&pdev->dev) || !of_node)
> > +               return 0;
> > +
> > +       sdev->clk_count = of_clk_get_parent_count(of_node);
> > +       if (!sdev->clk_count)
> > +               return 0;
> > +
> > +       sdev->clks = drmm_kzalloc(dev, sdev->clk_count * sizeof(sdev->clks[0]),
> > +                                 GFP_KERNEL);
> > +       if (!sdev->clks)
> > +               return -ENOMEM;
> > +
> > +       for (i = 0; i < sdev->clk_count; ++i) {
> > +               clock = of_clk_get(of_node, i);
> 
> clk_bulk_get_all()?

Plus then you can use devm_clk_bulk_get_all, even less code I think.
-Daniel

> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> -- 
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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[PATCH 7/9] drm/simplekms: Acquire regulators from DT device node

[Thomas Zimmermann]

Make sure required hardware regulators are enabled while the firmware
framebuffer is in use.

The basic code has been taken from the simplefb driver and adapted
to DRM. Regulators are released automatically via devres helpers.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/simplekms.c | 128 +++++++++++++++++++++++++++++++
 1 file changed, 128 insertions(+)

diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
index aca186decb48..ae5d3cbadbe8 100644
--- a/drivers/gpu/drm/tiny/simplekms.c
+++ b/drivers/gpu/drm/tiny/simplekms.c
@@ -4,6 +4,7 @@
 #include <linux/of_clk.h>
 #include <linux/platform_data/simplefb.h>
 #include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
 
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_connector.h>
@@ -198,6 +199,11 @@ struct simplekms_device {
 	unsigned int clk_count;
 	struct clk **clks;
 #endif
+	/* regulators */
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+	unsigned int regulator_count;
+	struct regulator **regulators;
+#endif
 
 	/* simplefb settings */
 	struct drm_display_mode mode;
@@ -315,6 +321,125 @@ static int simplekms_device_init_clocks(struct simplekms_device *sdev)
 }
 #endif
 
+#if defined CONFIG_OF && defined CONFIG_REGULATOR
+
+#define SUPPLY_SUFFIX "-supply"
+
+/*
+ * Regulator handling code.
+ *
+ * Here we handle the num-supplies and vin*-supply properties of our
+ * "simple-framebuffer" dt node. This is necessary so that we can make sure
+ * that any regulators needed by the display hardware that the bootloader
+ * set up for us (and for which it provided a simplefb dt node), stay up,
+ * for the life of the simplefb driver.
+ *
+ * When the driver unloads, we cleanly disable, and then release the
+ * regulators.
+ *
+ * We only complain about errors here, no action is taken as the most likely
+ * error can only happen due to a mismatch between the bootloader which set
+ * up simplefb, and the regulator definitions in the device tree. Chances are
+ * that there are no adverse effects, and if there are, a clean teardown of
+ * the fb probe will not help us much either. So just complain and carry on,
+ * and hope that the user actually gets a working fb at the end of things.
+ */
+
+static void simplekms_device_release_regulators(void *res)
+{
+	struct simplekms_device *sdev = simplekms_device_of_dev(res);
+	unsigned int i;
+
+	for (i = 0; i < sdev->regulator_count; ++i) {
+		if (sdev->regulators[i]) {
+			regulator_disable(sdev->regulators[i]);
+			regulator_put(sdev->regulators[i]);
+		}
+	}
+}
+
+static int simplekms_device_init_regulators(struct simplekms_device *sdev)
+{
+	struct drm_device *dev = &sdev->dev;
+	struct platform_device *pdev = sdev->pdev;
+	struct device_node *of_node = pdev->dev.of_node;
+	struct property *prop;
+	struct regulator *regulator;
+	const char *p;
+	unsigned int count = 0, i = 0;
+	int ret;
+
+	if (dev_get_platdata(&pdev->dev) || !of_node)
+		return 0;
+
+	/* Count the number of regulator supplies */
+	for_each_property_of_node(of_node, prop) {
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (p && p != prop->name)
+			++count;
+	}
+
+	if (!count)
+		return 0;
+
+	sdev->regulators = drmm_kzalloc(dev,
+					count * sizeof(sdev->regulators[0]),
+					GFP_KERNEL);
+	if (!sdev->regulators)
+		return -ENOMEM;
+
+	for_each_property_of_node(of_node, prop) {
+		char name[32]; /* 32 is max size of property name */
+		size_t len;
+
+		p = strstr(prop->name, SUPPLY_SUFFIX);
+		if (!p || p == prop->name)
+			continue;
+		len = strlen(prop->name) - strlen(SUPPLY_SUFFIX) + 1;
+		strlcpy(name, prop->name, len);
+
+		regulator = regulator_get_optional(&pdev->dev, name);
+		if (IS_ERR(regulator)) {
+			ret = PTR_ERR(regulator);
+			if (ret == -EPROBE_DEFER)
+				goto err;
+			drm_err(dev, "regulator %s not found: %d\n",
+				name, ret);
+			continue;
+		}
+
+		ret = regulator_enable(regulator);
+		if (ret) {
+			drm_err(dev, "failed to enable regulator %u: %d\n",
+				i, ret);
+			regulator_put(regulator);
+		}
+
+		sdev->regulators[i++] = regulator;
+	}
+	sdev->regulator_count = i;
+
+	return devm_add_action_or_reset(&pdev->dev,
+					simplekms_device_release_regulators,
+					sdev);
+
+err:
+	while (i) {
+		--i;
+		if (sdev->regulators[i]) {
+			regulator_disable(sdev->regulators[i]);
+			regulator_put(sdev->regulators[i]);
+		}
+	}
+	return ret;
+}
+#else
+static int simplekms_device_init_regulators(struct simplekms_device *sdev)
+{
+	return 0;
+}
+#endif
+
 /*
  *  Simplefb settings
  */
@@ -611,6 +736,9 @@ simplekms_device_create(struct drm_driver *drv, struct platform_device *pdev)
 	sdev->pdev = pdev;
 
 	ret = simplekms_device_init_clocks(sdev);
+	if (ret)
+		return ERR_PTR(ret);
+	ret = simplekms_device_init_regulators(sdev);
 	if (ret)
 		return ERR_PTR(ret);
 	ret = simplekms_device_init_fb(sdev);
-- 
2.27.0

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Re: [PATCH 7/9] drm/simplekms: Acquire regulators from DT device node

[Geert Uytterhoeven]

Hi Thomas,

On Thu, Jun 25, 2020 at 2:00 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
> Make sure required hardware regulators are enabled while the firmware
> framebuffer is in use.
>
> The basic code has been taken from the simplefb driver and adapted
> to DRM. Regulators are released automatically via devres helpers.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Thanks for your patch!

> --- a/drivers/gpu/drm/tiny/simplekms.c
> +++ b/drivers/gpu/drm/tiny/simplekms.c
> @@ -4,6 +4,7 @@
>  #include <linux/of_clk.h>
>  #include <linux/platform_data/simplefb.h>
>  #include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
>
>  #include <drm/drm_atomic_state_helper.h>
>  #include <drm/drm_connector.h>
> @@ -198,6 +199,11 @@ struct simplekms_device {
>         unsigned int clk_count;
>         struct clk **clks;
>  #endif
> +       /* regulators */
> +#if defined CONFIG_OF && defined CONFIG_REGULATOR
> +       unsigned int regulator_count;
> +       struct regulator **regulators;
> +#endif
>
>         /* simplefb settings */
>         struct drm_display_mode mode;
> @@ -315,6 +321,125 @@ static int simplekms_device_init_clocks(struct simplekms_device *sdev)
>  }
>  #endif
>
> +#if defined CONFIG_OF && defined CONFIG_REGULATOR
> +
> +#define SUPPLY_SUFFIX "-supply"
> +
> +/*
> + * Regulator handling code.
> + *
> + * Here we handle the num-supplies and vin*-supply properties of our
> + * "simple-framebuffer" dt node. This is necessary so that we can make sure
> + * that any regulators needed by the display hardware that the bootloader
> + * set up for us (and for which it provided a simplefb dt node), stay up,
> + * for the life of the simplefb driver.

Looks like there's a bulk regulator API, too?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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[PATCH 8/9] drm: Add infrastructure for platform devices

[Thomas Zimmermann]

Platform devices might operate on firmware framebuffers, such as VESA or
EFI. Before a native driver for the graphics hardware can take over the
device, it has to remove any platform driver that operates on the firmware
framebuffer. Platform helpers provide the infrastructure for platform
drivers to acquire firmware framebuffers, and for native drivers to remove
them lateron.

It works similar to the related fbdev mechanism. During initialization, the
platform driver acquires the firmware framebuffer's I/O memory and provides
a callback to be removed. The native driver later uses this inforamtion to
remove any platform driver for it's framebuffer I/O memory.

The platform helper's removal code is integrated into the existing code for
removing conflicting fraembuffers, so native drivers use it automatically.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/Kconfig        |   6 ++
 drivers/gpu/drm/Makefile       |   1 +
 drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
 include/drm/drm_fb_helper.h    |  18 ++++-
 include/drm/drm_platform.h     |  42 ++++++++++++
 5 files changed, 184 insertions(+), 1 deletion(-)
 create mode 100644 drivers/gpu/drm/drm_platform.c
 create mode 100644 include/drm/drm_platform.h

diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index c4fd57d8b717..e9d6892f9d38 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -229,6 +229,12 @@ config DRM_SCHED
 	tristate
 	depends on DRM
 
+config DRM_PLATFORM_HELPER
+	bool
+	depends on DRM
+	help
+	  Helpers for DRM platform devices
+
 source "drivers/gpu/drm/i2c/Kconfig"
 
 source "drivers/gpu/drm/arm/Kconfig"
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 2c0e5a7e5953..8ceb21d0770a 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
 drm-$(CONFIG_PCI) += drm_pci.o
 drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
 drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
+drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
 
 drm_vram_helper-y := drm_gem_vram_helper.o
 obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
new file mode 100644
index 000000000000..09a2f2a31aa5
--- /dev/null
+++ b/drivers/gpu/drm/drm_platform.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+#include <linux/mutex.h>
+#include <linux/slab.h>
+
+#include <drm/drm_drv.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_platform.h>
+
+static LIST_HEAD(drm_apertures);
+
+static DEFINE_MUTEX(drm_apertures_lock);
+
+static bool overlap(resource_size_t base1, resource_size_t end1,
+		    resource_size_t base2, resource_size_t end2)
+{
+	return (base1 < end2) && (end1 > base2);
+}
+
+static struct drm_aperture *
+drm_aperture_acquire(struct drm_device *dev,
+		     resource_size_t base, resource_size_t size,
+		     const struct drm_aperture_funcs *funcs)
+{
+	size_t end = base + size;
+	struct list_head *pos;
+	struct drm_aperture *ap;
+
+	mutex_lock(&drm_apertures_lock);
+
+	list_for_each(pos, &drm_apertures) {
+		ap = container_of(pos, struct drm_aperture, lh);
+		if (overlap(base, end, ap->base, ap->base + ap->size))
+			return ERR_PTR(-EBUSY);
+	}
+
+	ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
+	if (!ap)
+		return ERR_PTR(-ENOMEM);
+
+	ap->dev = dev;
+	ap->base = base;
+	ap->size = size;
+	ap->funcs = funcs;
+	INIT_LIST_HEAD(&ap->lh);
+
+	list_add(&ap->lh, &drm_apertures);
+
+	mutex_unlock(&drm_apertures_lock);
+
+	return ap;
+}
+
+static void drm_aperture_release(struct drm_aperture *ap)
+{
+	bool kicked_out = ap->kicked_out;
+
+	if (!kicked_out)
+		mutex_lock(&drm_apertures_lock);
+
+	list_del(&ap->lh);
+	if (ap->funcs->release)
+		ap->funcs->release(ap);
+
+	if (!kicked_out)
+		mutex_unlock(&drm_apertures_lock);
+}
+
+static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
+{
+	struct drm_aperture *ap = ptr;
+
+	drm_aperture_release(ap);
+}
+
+struct drm_aperture *
+drmm_aperture_acquire(struct drm_device *dev,
+		      resource_size_t base, resource_size_t size,
+		      const struct drm_aperture_funcs *funcs)
+{
+	struct drm_aperture *ap;
+	int ret;
+
+	ap = drm_aperture_acquire(dev, base, size, funcs);
+	if (IS_ERR(ap))
+		return ap;
+	ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return ap;
+}
+EXPORT_SYMBOL(drmm_aperture_acquire);
+
+void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
+{
+	resource_size_t end = base + size;
+	struct list_head *pos, *n;
+
+	mutex_lock(&drm_apertures_lock);
+
+	list_for_each_safe(pos, n, &drm_apertures) {
+		struct drm_aperture *ap =
+			container_of(pos, struct drm_aperture, lh);
+
+		if (!overlap(base, end, ap->base, ap->base + ap->size))
+			continue;
+
+		ap->kicked_out = true;
+		if (ap->funcs->kickout)
+			ap->funcs->kickout(ap);
+		else
+			drm_dev_put(ap->dev);
+	}
+
+	mutex_unlock(&drm_apertures_lock);
+}
+EXPORT_SYMBOL(drm_kickout_apertures_at);
diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
index 306aa3a60be9..a919b78b1961 100644
--- a/include/drm/drm_fb_helper.h
+++ b/include/drm/drm_fb_helper.h
@@ -35,7 +35,9 @@ struct drm_fb_helper;
 #include <drm/drm_client.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_device.h>
+#include <drm/drm_platform.h>
 #include <linux/kgdb.h>
+#include <linux/pci.h>
 #include <linux/vgaarb.h>
 
 enum mode_set_atomic {
@@ -465,6 +467,11 @@ static inline int
 drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
 					      const char *name, bool primary)
 {
+	int i;
+
+	for (i = 0; i < a->count; ++i)
+		drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
+
 #if IS_REACHABLE(CONFIG_FB)
 	return remove_conflicting_framebuffers(a, name, primary);
 #else
@@ -487,7 +494,16 @@ static inline int
 drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
 						  const char *name)
 {
-	int ret = 0;
+	resource_size_t base, size;
+	int bar, ret = 0;
+
+	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
+		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
+			continue;
+		base = pci_resource_start(pdev, bar);
+		size = pci_resource_len(pdev, bar);
+		drm_kickout_apertures_at(base, size);
+	}
 
 	/*
 	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
new file mode 100644
index 000000000000..475e88ee1fbd
--- /dev/null
+++ b/include/drm/drm_platform.h
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+
+#ifndef _DRM_PLATFORM_H_
+#define _DRM_PLATFORM_H_
+
+#include <linux/list.h>
+#include <linux/types.h>
+
+struct drm_aperture;
+struct drm_device;
+
+struct drm_aperture_funcs {
+	void (*kickout)(struct drm_aperture *ap);
+	void (*release)(struct drm_aperture *ap);
+};
+
+struct drm_aperture {
+	struct drm_device *dev;
+	resource_size_t base;
+	resource_size_t size;
+
+	const struct drm_aperture_funcs *funcs;
+
+	struct list_head lh;
+	bool kicked_out;
+};
+
+struct drm_aperture *
+drmm_aperture_acquire(struct drm_device *dev,
+		      resource_size_t base, resource_size_t size,
+		      const struct drm_aperture_funcs *funcs);
+
+#if defined (CONFIG_DRM_PLATFORM_HELPER)
+void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
+#else
+static inline void
+drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
+{
+}
+#endif
+
+#endif
-- 
2.27.0

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Re: [PATCH 8/9] drm: Add infrastructure for platform devices

[Daniel Vetter]

On Thu, Jun 25, 2020 at 02:00:10PM +0200, Thomas Zimmermann wrote:
> Platform devices might operate on firmware framebuffers, such as VESA or
> EFI. Before a native driver for the graphics hardware can take over the
> device, it has to remove any platform driver that operates on the firmware
> framebuffer. Platform helpers provide the infrastructure for platform
> drivers to acquire firmware framebuffers, and for native drivers to remove
> them lateron.
> 
> It works similar to the related fbdev mechanism. During initialization, the
> platform driver acquires the firmware framebuffer's I/O memory and provides
> a callback to be removed. The native driver later uses this inforamtion to
> remove any platform driver for it's framebuffer I/O memory.
> 
> The platform helper's removal code is integrated into the existing code for
> removing conflicting fraembuffers, so native drivers use it automatically.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

I have some ideas for how to do this a notch cleaner in the next patch.
Maybe best to discuss the actual implmenentation stuff there.

Aside from that usual nits:
- kerneldoc for these please, pulled into drm-kms.rst.
- naming isn't super ocd with drm_platform.c but that prefix not used, but
  I also don't have better ideas.
- I think the functions from drm_fb_helper.h for removing other
  framebuffers should be moved here, and function name prefix adjusted
  acoordingly

I'm wondering about the locking and deadlock potential here, is lockdep
all happy with this?

Cheers, Daniel

> ---
>  drivers/gpu/drm/Kconfig        |   6 ++
>  drivers/gpu/drm/Makefile       |   1 +
>  drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
>  include/drm/drm_fb_helper.h    |  18 ++++-
>  include/drm/drm_platform.h     |  42 ++++++++++++
>  5 files changed, 184 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/drm_platform.c
>  create mode 100644 include/drm/drm_platform.h
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index c4fd57d8b717..e9d6892f9d38 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -229,6 +229,12 @@ config DRM_SCHED
>  	tristate
>  	depends on DRM
>  
> +config DRM_PLATFORM_HELPER
> +	bool
> +	depends on DRM
> +	help
> +	  Helpers for DRM platform devices
> +
>  source "drivers/gpu/drm/i2c/Kconfig"
>  
>  source "drivers/gpu/drm/arm/Kconfig"
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 2c0e5a7e5953..8ceb21d0770a 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>  drm-$(CONFIG_PCI) += drm_pci.o
>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> +drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
>  
>  drm_vram_helper-y := drm_gem_vram_helper.o
>  obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
> diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
> new file mode 100644
> index 000000000000..09a2f2a31aa5
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_platform.c
> @@ -0,0 +1,118 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +
> +#include <drm/drm_drv.h>
> +#include <drm/drm_managed.h>
> +#include <drm/drm_platform.h>
> +
> +static LIST_HEAD(drm_apertures);
> +
> +static DEFINE_MUTEX(drm_apertures_lock);
> +
> +static bool overlap(resource_size_t base1, resource_size_t end1,
> +		    resource_size_t base2, resource_size_t end2)
> +{
> +	return (base1 < end2) && (end1 > base2);
> +}
> +
> +static struct drm_aperture *
> +drm_aperture_acquire(struct drm_device *dev,
> +		     resource_size_t base, resource_size_t size,
> +		     const struct drm_aperture_funcs *funcs)
> +{
> +	size_t end = base + size;
> +	struct list_head *pos;
> +	struct drm_aperture *ap;
> +
> +	mutex_lock(&drm_apertures_lock);
> +
> +	list_for_each(pos, &drm_apertures) {
> +		ap = container_of(pos, struct drm_aperture, lh);
> +		if (overlap(base, end, ap->base, ap->base + ap->size))
> +			return ERR_PTR(-EBUSY);
> +	}
> +
> +	ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
> +	if (!ap)
> +		return ERR_PTR(-ENOMEM);
> +
> +	ap->dev = dev;
> +	ap->base = base;
> +	ap->size = size;
> +	ap->funcs = funcs;
> +	INIT_LIST_HEAD(&ap->lh);
> +
> +	list_add(&ap->lh, &drm_apertures);
> +
> +	mutex_unlock(&drm_apertures_lock);
> +
> +	return ap;
> +}
> +
> +static void drm_aperture_release(struct drm_aperture *ap)
> +{
> +	bool kicked_out = ap->kicked_out;
> +
> +	if (!kicked_out)
> +		mutex_lock(&drm_apertures_lock);
> +
> +	list_del(&ap->lh);
> +	if (ap->funcs->release)
> +		ap->funcs->release(ap);
> +
> +	if (!kicked_out)
> +		mutex_unlock(&drm_apertures_lock);
> +}
> +
> +static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
> +{
> +	struct drm_aperture *ap = ptr;
> +
> +	drm_aperture_release(ap);
> +}
> +
> +struct drm_aperture *
> +drmm_aperture_acquire(struct drm_device *dev,
> +		      resource_size_t base, resource_size_t size,
> +		      const struct drm_aperture_funcs *funcs)
> +{
> +	struct drm_aperture *ap;
> +	int ret;
> +
> +	ap = drm_aperture_acquire(dev, base, size, funcs);
> +	if (IS_ERR(ap))
> +		return ap;
> +	ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return ap;
> +}
> +EXPORT_SYMBOL(drmm_aperture_acquire);
> +
> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> +{
> +	resource_size_t end = base + size;
> +	struct list_head *pos, *n;
> +
> +	mutex_lock(&drm_apertures_lock);
> +
> +	list_for_each_safe(pos, n, &drm_apertures) {
> +		struct drm_aperture *ap =
> +			container_of(pos, struct drm_aperture, lh);
> +
> +		if (!overlap(base, end, ap->base, ap->base + ap->size))
> +			continue;
> +
> +		ap->kicked_out = true;
> +		if (ap->funcs->kickout)
> +			ap->funcs->kickout(ap);
> +		else
> +			drm_dev_put(ap->dev);
> +	}
> +
> +	mutex_unlock(&drm_apertures_lock);
> +}
> +EXPORT_SYMBOL(drm_kickout_apertures_at);
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 306aa3a60be9..a919b78b1961 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -35,7 +35,9 @@ struct drm_fb_helper;
>  #include <drm/drm_client.h>
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_device.h>
> +#include <drm/drm_platform.h>
>  #include <linux/kgdb.h>
> +#include <linux/pci.h>
>  #include <linux/vgaarb.h>
>  
>  enum mode_set_atomic {
> @@ -465,6 +467,11 @@ static inline int
>  drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
>  					      const char *name, bool primary)
>  {
> +	int i;
> +
> +	for (i = 0; i < a->count; ++i)
> +		drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
> +
>  #if IS_REACHABLE(CONFIG_FB)
>  	return remove_conflicting_framebuffers(a, name, primary);
>  #else
> @@ -487,7 +494,16 @@ static inline int
>  drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
>  						  const char *name)
>  {
> -	int ret = 0;
> +	resource_size_t base, size;
> +	int bar, ret = 0;
> +
> +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> +		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> +			continue;
> +		base = pci_resource_start(pdev, bar);
> +		size = pci_resource_len(pdev, bar);
> +		drm_kickout_apertures_at(base, size);
> +	}
>  
>  	/*
>  	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
> diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
> new file mode 100644
> index 000000000000..475e88ee1fbd
> --- /dev/null
> +++ b/include/drm/drm_platform.h
> @@ -0,0 +1,42 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +#ifndef _DRM_PLATFORM_H_
> +#define _DRM_PLATFORM_H_
> +
> +#include <linux/list.h>
> +#include <linux/types.h>
> +
> +struct drm_aperture;
> +struct drm_device;
> +
> +struct drm_aperture_funcs {
> +	void (*kickout)(struct drm_aperture *ap);
> +	void (*release)(struct drm_aperture *ap);
> +};
> +
> +struct drm_aperture {
> +	struct drm_device *dev;
> +	resource_size_t base;
> +	resource_size_t size;
> +
> +	const struct drm_aperture_funcs *funcs;
> +
> +	struct list_head lh;
> +	bool kicked_out;
> +};
> +
> +struct drm_aperture *
> +drmm_aperture_acquire(struct drm_device *dev,
> +		      resource_size_t base, resource_size_t size,
> +		      const struct drm_aperture_funcs *funcs);
> +
> +#if defined (CONFIG_DRM_PLATFORM_HELPER)
> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
> +#else
> +static inline void
> +drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> +{
> +}
> +#endif
> +
> +#endif
> -- 
> 2.27.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 8/9] drm: Add infrastructure for platform devices

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 9848 bytes --]

Hi

Am 29.06.20 um 11:27 schrieb Daniel Vetter:
> On Thu, Jun 25, 2020 at 02:00:10PM +0200, Thomas Zimmermann wrote:
>> Platform devices might operate on firmware framebuffers, such as VESA or
>> EFI. Before a native driver for the graphics hardware can take over the
>> device, it has to remove any platform driver that operates on the firmware
>> framebuffer. Platform helpers provide the infrastructure for platform
>> drivers to acquire firmware framebuffers, and for native drivers to remove
>> them lateron.
>>
>> It works similar to the related fbdev mechanism. During initialization, the
>> platform driver acquires the firmware framebuffer's I/O memory and provides
>> a callback to be removed. The native driver later uses this inforamtion to
>> remove any platform driver for it's framebuffer I/O memory.
>>
>> The platform helper's removal code is integrated into the existing code for
>> removing conflicting fraembuffers, so native drivers use it automatically.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> I have some ideas for how to do this a notch cleaner in the next patch.
> Maybe best to discuss the actual implmenentation stuff there.
> 
> Aside from that usual nits:
> - kerneldoc for these please, pulled into drm-kms.rst.
> - naming isn't super ocd with drm_platform.c but that prefix not used, but
>   I also don't have better ideas.

I was never really happy with the naming either. Maybe call it aperture
helpers with drm_aperture_ and CONFIG_DRM_APERTURE_HELPER?

> - I think the functions from drm_fb_helper.h for removing other
>   framebuffers should be moved here, and function name prefix adjusted
>   acoordingly
> 
> I'm wondering about the locking and deadlock potential here, is lockdep
> all happy with this?

I haven't seen any complains, but I'll double check.

Best regards
Thomas

> 
> Cheers, Daniel
> 
>> ---
>>  drivers/gpu/drm/Kconfig        |   6 ++
>>  drivers/gpu/drm/Makefile       |   1 +
>>  drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
>>  include/drm/drm_fb_helper.h    |  18 ++++-
>>  include/drm/drm_platform.h     |  42 ++++++++++++
>>  5 files changed, 184 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/gpu/drm/drm_platform.c
>>  create mode 100644 include/drm/drm_platform.h
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index c4fd57d8b717..e9d6892f9d38 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -229,6 +229,12 @@ config DRM_SCHED
>>  	tristate
>>  	depends on DRM
>>  
>> +config DRM_PLATFORM_HELPER
>> +	bool
>> +	depends on DRM
>> +	help
>> +	  Helpers for DRM platform devices
>> +
>>  source "drivers/gpu/drm/i2c/Kconfig"
>>  
>>  source "drivers/gpu/drm/arm/Kconfig"
>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>> index 2c0e5a7e5953..8ceb21d0770a 100644
>> --- a/drivers/gpu/drm/Makefile
>> +++ b/drivers/gpu/drm/Makefile
>> @@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>>  drm-$(CONFIG_PCI) += drm_pci.o
>>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
>>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
>> +drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
>>  
>>  drm_vram_helper-y := drm_gem_vram_helper.o
>>  obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
>> diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
>> new file mode 100644
>> index 000000000000..09a2f2a31aa5
>> --- /dev/null
>> +++ b/drivers/gpu/drm/drm_platform.c
>> @@ -0,0 +1,118 @@
>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>> +
>> +#include <linux/mutex.h>
>> +#include <linux/slab.h>
>> +
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_managed.h>
>> +#include <drm/drm_platform.h>
>> +
>> +static LIST_HEAD(drm_apertures);
>> +
>> +static DEFINE_MUTEX(drm_apertures_lock);
>> +
>> +static bool overlap(resource_size_t base1, resource_size_t end1,
>> +		    resource_size_t base2, resource_size_t end2)
>> +{
>> +	return (base1 < end2) && (end1 > base2);
>> +}
>> +
>> +static struct drm_aperture *
>> +drm_aperture_acquire(struct drm_device *dev,
>> +		     resource_size_t base, resource_size_t size,
>> +		     const struct drm_aperture_funcs *funcs)
>> +{
>> +	size_t end = base + size;
>> +	struct list_head *pos;
>> +	struct drm_aperture *ap;
>> +
>> +	mutex_lock(&drm_apertures_lock);
>> +
>> +	list_for_each(pos, &drm_apertures) {
>> +		ap = container_of(pos, struct drm_aperture, lh);
>> +		if (overlap(base, end, ap->base, ap->base + ap->size))
>> +			return ERR_PTR(-EBUSY);
>> +	}
>> +
>> +	ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
>> +	if (!ap)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	ap->dev = dev;
>> +	ap->base = base;
>> +	ap->size = size;
>> +	ap->funcs = funcs;
>> +	INIT_LIST_HEAD(&ap->lh);
>> +
>> +	list_add(&ap->lh, &drm_apertures);
>> +
>> +	mutex_unlock(&drm_apertures_lock);
>> +
>> +	return ap;
>> +}
>> +
>> +static void drm_aperture_release(struct drm_aperture *ap)
>> +{
>> +	bool kicked_out = ap->kicked_out;
>> +
>> +	if (!kicked_out)
>> +		mutex_lock(&drm_apertures_lock);
>> +
>> +	list_del(&ap->lh);
>> +	if (ap->funcs->release)
>> +		ap->funcs->release(ap);
>> +
>> +	if (!kicked_out)
>> +		mutex_unlock(&drm_apertures_lock);
>> +}
>> +
>> +static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
>> +{
>> +	struct drm_aperture *ap = ptr;
>> +
>> +	drm_aperture_release(ap);
>> +}
>> +
>> +struct drm_aperture *
>> +drmm_aperture_acquire(struct drm_device *dev,
>> +		      resource_size_t base, resource_size_t size,
>> +		      const struct drm_aperture_funcs *funcs)
>> +{
>> +	struct drm_aperture *ap;
>> +	int ret;
>> +
>> +	ap = drm_aperture_acquire(dev, base, size, funcs);
>> +	if (IS_ERR(ap))
>> +		return ap;
>> +	ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	return ap;
>> +}
>> +EXPORT_SYMBOL(drmm_aperture_acquire);
>> +
>> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
>> +{
>> +	resource_size_t end = base + size;
>> +	struct list_head *pos, *n;
>> +
>> +	mutex_lock(&drm_apertures_lock);
>> +
>> +	list_for_each_safe(pos, n, &drm_apertures) {
>> +		struct drm_aperture *ap =
>> +			container_of(pos, struct drm_aperture, lh);
>> +
>> +		if (!overlap(base, end, ap->base, ap->base + ap->size))
>> +			continue;
>> +
>> +		ap->kicked_out = true;
>> +		if (ap->funcs->kickout)
>> +			ap->funcs->kickout(ap);
>> +		else
>> +			drm_dev_put(ap->dev);
>> +	}
>> +
>> +	mutex_unlock(&drm_apertures_lock);
>> +}
>> +EXPORT_SYMBOL(drm_kickout_apertures_at);
>> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
>> index 306aa3a60be9..a919b78b1961 100644
>> --- a/include/drm/drm_fb_helper.h
>> +++ b/include/drm/drm_fb_helper.h
>> @@ -35,7 +35,9 @@ struct drm_fb_helper;
>>  #include <drm/drm_client.h>
>>  #include <drm/drm_crtc.h>
>>  #include <drm/drm_device.h>
>> +#include <drm/drm_platform.h>
>>  #include <linux/kgdb.h>
>> +#include <linux/pci.h>
>>  #include <linux/vgaarb.h>
>>  
>>  enum mode_set_atomic {
>> @@ -465,6 +467,11 @@ static inline int
>>  drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
>>  					      const char *name, bool primary)
>>  {
>> +	int i;
>> +
>> +	for (i = 0; i < a->count; ++i)
>> +		drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
>> +
>>  #if IS_REACHABLE(CONFIG_FB)
>>  	return remove_conflicting_framebuffers(a, name, primary);
>>  #else
>> @@ -487,7 +494,16 @@ static inline int
>>  drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
>>  						  const char *name)
>>  {
>> -	int ret = 0;
>> +	resource_size_t base, size;
>> +	int bar, ret = 0;
>> +
>> +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
>> +		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
>> +			continue;
>> +		base = pci_resource_start(pdev, bar);
>> +		size = pci_resource_len(pdev, bar);
>> +		drm_kickout_apertures_at(base, size);
>> +	}
>>  
>>  	/*
>>  	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
>> diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
>> new file mode 100644
>> index 000000000000..475e88ee1fbd
>> --- /dev/null
>> +++ b/include/drm/drm_platform.h
>> @@ -0,0 +1,42 @@
>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>> +
>> +#ifndef _DRM_PLATFORM_H_
>> +#define _DRM_PLATFORM_H_
>> +
>> +#include <linux/list.h>
>> +#include <linux/types.h>
>> +
>> +struct drm_aperture;
>> +struct drm_device;
>> +
>> +struct drm_aperture_funcs {
>> +	void (*kickout)(struct drm_aperture *ap);
>> +	void (*release)(struct drm_aperture *ap);
>> +};
>> +
>> +struct drm_aperture {
>> +	struct drm_device *dev;
>> +	resource_size_t base;
>> +	resource_size_t size;
>> +
>> +	const struct drm_aperture_funcs *funcs;
>> +
>> +	struct list_head lh;
>> +	bool kicked_out;
>> +};
>> +
>> +struct drm_aperture *
>> +drmm_aperture_acquire(struct drm_device *dev,
>> +		      resource_size_t base, resource_size_t size,
>> +		      const struct drm_aperture_funcs *funcs);
>> +
>> +#if defined (CONFIG_DRM_PLATFORM_HELPER)
>> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
>> +#else
>> +static inline void
>> +drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
>> +{
>> +}
>> +#endif
>> +
>> +#endif
>> -- 
>> 2.27.0
>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 8/9] drm: Add infrastructure for platform devices

[Daniel Vetter]

On Mon, Sep 28, 2020 at 10:40 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
> Hi
>
> Am 29.06.20 um 11:27 schrieb Daniel Vetter:
> > On Thu, Jun 25, 2020 at 02:00:10PM +0200, Thomas Zimmermann wrote:
> >> Platform devices might operate on firmware framebuffers, such as VESA or
> >> EFI. Before a native driver for the graphics hardware can take over the
> >> device, it has to remove any platform driver that operates on the firmware
> >> framebuffer. Platform helpers provide the infrastructure for platform
> >> drivers to acquire firmware framebuffers, and for native drivers to remove
> >> them lateron.
> >>
> >> It works similar to the related fbdev mechanism. During initialization, the
> >> platform driver acquires the firmware framebuffer's I/O memory and provides
> >> a callback to be removed. The native driver later uses this inforamtion to
> >> remove any platform driver for it's framebuffer I/O memory.
> >>
> >> The platform helper's removal code is integrated into the existing code for
> >> removing conflicting fraembuffers, so native drivers use it automatically.
> >>
> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> >
> > I have some ideas for how to do this a notch cleaner in the next patch.
> > Maybe best to discuss the actual implmenentation stuff there.
> >
> > Aside from that usual nits:
> > - kerneldoc for these please, pulled into drm-kms.rst.
> > - naming isn't super ocd with drm_platform.c but that prefix not used, but
> >   I also don't have better ideas.
>
> I was never really happy with the naming either. Maybe call it aperture
> helpers with drm_aperture_ and CONFIG_DRM_APERTURE_HELPER?

+1

> > - I think the functions from drm_fb_helper.h for removing other
> >   framebuffers should be moved here, and function name prefix adjusted
> >   acoordingly
> >
> > I'm wondering about the locking and deadlock potential here, is lockdep
> > all happy with this?
>
> I haven't seen any complains, but I'll double check.

Might be worth it to cc Greg on this, since the device driver model
has a lot of corner cases to make sure it doesn't get stuck here with
hiararchical drivers/device getting removed while something else is
probing them at the same time.
-Daniel

> Best regards
> Thomas
>
> >
> > Cheers, Daniel
> >
> >> ---
> >>  drivers/gpu/drm/Kconfig        |   6 ++
> >>  drivers/gpu/drm/Makefile       |   1 +
> >>  drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
> >>  include/drm/drm_fb_helper.h    |  18 ++++-
> >>  include/drm/drm_platform.h     |  42 ++++++++++++
> >>  5 files changed, 184 insertions(+), 1 deletion(-)
> >>  create mode 100644 drivers/gpu/drm/drm_platform.c
> >>  create mode 100644 include/drm/drm_platform.h
> >>
> >> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> >> index c4fd57d8b717..e9d6892f9d38 100644
> >> --- a/drivers/gpu/drm/Kconfig
> >> +++ b/drivers/gpu/drm/Kconfig
> >> @@ -229,6 +229,12 @@ config DRM_SCHED
> >>      tristate
> >>      depends on DRM
> >>
> >> +config DRM_PLATFORM_HELPER
> >> +    bool
> >> +    depends on DRM
> >> +    help
> >> +      Helpers for DRM platform devices
> >> +
> >>  source "drivers/gpu/drm/i2c/Kconfig"
> >>
> >>  source "drivers/gpu/drm/arm/Kconfig"
> >> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> >> index 2c0e5a7e5953..8ceb21d0770a 100644
> >> --- a/drivers/gpu/drm/Makefile
> >> +++ b/drivers/gpu/drm/Makefile
> >> @@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
> >>  drm-$(CONFIG_PCI) += drm_pci.o
> >>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
> >>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> >> +drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
> >>
> >>  drm_vram_helper-y := drm_gem_vram_helper.o
> >>  obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
> >> diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
> >> new file mode 100644
> >> index 000000000000..09a2f2a31aa5
> >> --- /dev/null
> >> +++ b/drivers/gpu/drm/drm_platform.c
> >> @@ -0,0 +1,118 @@
> >> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> >> +
> >> +#include <linux/mutex.h>
> >> +#include <linux/slab.h>
> >> +
> >> +#include <drm/drm_drv.h>
> >> +#include <drm/drm_managed.h>
> >> +#include <drm/drm_platform.h>
> >> +
> >> +static LIST_HEAD(drm_apertures);
> >> +
> >> +static DEFINE_MUTEX(drm_apertures_lock);
> >> +
> >> +static bool overlap(resource_size_t base1, resource_size_t end1,
> >> +                resource_size_t base2, resource_size_t end2)
> >> +{
> >> +    return (base1 < end2) && (end1 > base2);
> >> +}
> >> +
> >> +static struct drm_aperture *
> >> +drm_aperture_acquire(struct drm_device *dev,
> >> +                 resource_size_t base, resource_size_t size,
> >> +                 const struct drm_aperture_funcs *funcs)
> >> +{
> >> +    size_t end = base + size;
> >> +    struct list_head *pos;
> >> +    struct drm_aperture *ap;
> >> +
> >> +    mutex_lock(&drm_apertures_lock);
> >> +
> >> +    list_for_each(pos, &drm_apertures) {
> >> +            ap = container_of(pos, struct drm_aperture, lh);
> >> +            if (overlap(base, end, ap->base, ap->base + ap->size))
> >> +                    return ERR_PTR(-EBUSY);
> >> +    }
> >> +
> >> +    ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
> >> +    if (!ap)
> >> +            return ERR_PTR(-ENOMEM);
> >> +
> >> +    ap->dev = dev;
> >> +    ap->base = base;
> >> +    ap->size = size;
> >> +    ap->funcs = funcs;
> >> +    INIT_LIST_HEAD(&ap->lh);
> >> +
> >> +    list_add(&ap->lh, &drm_apertures);
> >> +
> >> +    mutex_unlock(&drm_apertures_lock);
> >> +
> >> +    return ap;
> >> +}
> >> +
> >> +static void drm_aperture_release(struct drm_aperture *ap)
> >> +{
> >> +    bool kicked_out = ap->kicked_out;
> >> +
> >> +    if (!kicked_out)
> >> +            mutex_lock(&drm_apertures_lock);
> >> +
> >> +    list_del(&ap->lh);
> >> +    if (ap->funcs->release)
> >> +            ap->funcs->release(ap);
> >> +
> >> +    if (!kicked_out)
> >> +            mutex_unlock(&drm_apertures_lock);
> >> +}
> >> +
> >> +static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
> >> +{
> >> +    struct drm_aperture *ap = ptr;
> >> +
> >> +    drm_aperture_release(ap);
> >> +}
> >> +
> >> +struct drm_aperture *
> >> +drmm_aperture_acquire(struct drm_device *dev,
> >> +                  resource_size_t base, resource_size_t size,
> >> +                  const struct drm_aperture_funcs *funcs)
> >> +{
> >> +    struct drm_aperture *ap;
> >> +    int ret;
> >> +
> >> +    ap = drm_aperture_acquire(dev, base, size, funcs);
> >> +    if (IS_ERR(ap))
> >> +            return ap;
> >> +    ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
> >> +    if (ret)
> >> +            return ERR_PTR(ret);
> >> +
> >> +    return ap;
> >> +}
> >> +EXPORT_SYMBOL(drmm_aperture_acquire);
> >> +
> >> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> >> +{
> >> +    resource_size_t end = base + size;
> >> +    struct list_head *pos, *n;
> >> +
> >> +    mutex_lock(&drm_apertures_lock);
> >> +
> >> +    list_for_each_safe(pos, n, &drm_apertures) {
> >> +            struct drm_aperture *ap =
> >> +                    container_of(pos, struct drm_aperture, lh);
> >> +
> >> +            if (!overlap(base, end, ap->base, ap->base + ap->size))
> >> +                    continue;
> >> +
> >> +            ap->kicked_out = true;
> >> +            if (ap->funcs->kickout)
> >> +                    ap->funcs->kickout(ap);
> >> +            else
> >> +                    drm_dev_put(ap->dev);
> >> +    }
> >> +
> >> +    mutex_unlock(&drm_apertures_lock);
> >> +}
> >> +EXPORT_SYMBOL(drm_kickout_apertures_at);
> >> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> >> index 306aa3a60be9..a919b78b1961 100644
> >> --- a/include/drm/drm_fb_helper.h
> >> +++ b/include/drm/drm_fb_helper.h
> >> @@ -35,7 +35,9 @@ struct drm_fb_helper;
> >>  #include <drm/drm_client.h>
> >>  #include <drm/drm_crtc.h>
> >>  #include <drm/drm_device.h>
> >> +#include <drm/drm_platform.h>
> >>  #include <linux/kgdb.h>
> >> +#include <linux/pci.h>
> >>  #include <linux/vgaarb.h>
> >>
> >>  enum mode_set_atomic {
> >> @@ -465,6 +467,11 @@ static inline int
> >>  drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
> >>                                            const char *name, bool primary)
> >>  {
> >> +    int i;
> >> +
> >> +    for (i = 0; i < a->count; ++i)
> >> +            drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
> >> +
> >>  #if IS_REACHABLE(CONFIG_FB)
> >>      return remove_conflicting_framebuffers(a, name, primary);
> >>  #else
> >> @@ -487,7 +494,16 @@ static inline int
> >>  drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
> >>                                                const char *name)
> >>  {
> >> -    int ret = 0;
> >> +    resource_size_t base, size;
> >> +    int bar, ret = 0;
> >> +
> >> +    for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> >> +            if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> >> +                    continue;
> >> +            base = pci_resource_start(pdev, bar);
> >> +            size = pci_resource_len(pdev, bar);
> >> +            drm_kickout_apertures_at(base, size);
> >> +    }
> >>
> >>      /*
> >>       * WARNING: Apparently we must kick fbdev drivers before vgacon,
> >> diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
> >> new file mode 100644
> >> index 000000000000..475e88ee1fbd
> >> --- /dev/null
> >> +++ b/include/drm/drm_platform.h
> >> @@ -0,0 +1,42 @@
> >> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> >> +
> >> +#ifndef _DRM_PLATFORM_H_
> >> +#define _DRM_PLATFORM_H_
> >> +
> >> +#include <linux/list.h>
> >> +#include <linux/types.h>
> >> +
> >> +struct drm_aperture;
> >> +struct drm_device;
> >> +
> >> +struct drm_aperture_funcs {
> >> +    void (*kickout)(struct drm_aperture *ap);
> >> +    void (*release)(struct drm_aperture *ap);
> >> +};
> >> +
> >> +struct drm_aperture {
> >> +    struct drm_device *dev;
> >> +    resource_size_t base;
> >> +    resource_size_t size;
> >> +
> >> +    const struct drm_aperture_funcs *funcs;
> >> +
> >> +    struct list_head lh;
> >> +    bool kicked_out;
> >> +};
> >> +
> >> +struct drm_aperture *
> >> +drmm_aperture_acquire(struct drm_device *dev,
> >> +                  resource_size_t base, resource_size_t size,
> >> +                  const struct drm_aperture_funcs *funcs);
> >> +
> >> +#if defined (CONFIG_DRM_PLATFORM_HELPER)
> >> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
> >> +#else
> >> +static inline void
> >> +drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> >> +{
> >> +}
> >> +#endif
> >> +
> >> +#endif
> >> --
> >> 2.27.0
> >>
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 8/9] drm: Add infrastructure for platform devices

[Thomas Zimmermann]

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Hi

Am 28.09.20 um 10:50 schrieb Daniel Vetter:
> On Mon, Sep 28, 2020 at 10:40 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>
>> Hi
>>
>> Am 29.06.20 um 11:27 schrieb Daniel Vetter:
>>> On Thu, Jun 25, 2020 at 02:00:10PM +0200, Thomas Zimmermann wrote:
>>>> Platform devices might operate on firmware framebuffers, such as VESA or
>>>> EFI. Before a native driver for the graphics hardware can take over the
>>>> device, it has to remove any platform driver that operates on the firmware
>>>> framebuffer. Platform helpers provide the infrastructure for platform
>>>> drivers to acquire firmware framebuffers, and for native drivers to remove
>>>> them lateron.
>>>>
>>>> It works similar to the related fbdev mechanism. During initialization, the
>>>> platform driver acquires the firmware framebuffer's I/O memory and provides
>>>> a callback to be removed. The native driver later uses this inforamtion to
>>>> remove any platform driver for it's framebuffer I/O memory.
>>>>
>>>> The platform helper's removal code is integrated into the existing code for
>>>> removing conflicting fraembuffers, so native drivers use it automatically.
>>>>
>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>
>>> I have some ideas for how to do this a notch cleaner in the next patch.
>>> Maybe best to discuss the actual implmenentation stuff there.
>>>
>>> Aside from that usual nits:
>>> - kerneldoc for these please, pulled into drm-kms.rst.
>>> - naming isn't super ocd with drm_platform.c but that prefix not used, but
>>>   I also don't have better ideas.
>>
>> I was never really happy with the naming either. Maybe call it aperture
>> helpers with drm_aperture_ and CONFIG_DRM_APERTURE_HELPER?
> 
> +1
> 
>>> - I think the functions from drm_fb_helper.h for removing other
>>>   framebuffers should be moved here, and function name prefix adjusted
>>>   acoordingly
>>>
>>> I'm wondering about the locking and deadlock potential here, is lockdep
>>> all happy with this?
>>
>> I haven't seen any complains, but I'll double check.
> 
> Might be worth it to cc Greg on this, since the device driver model
> has a lot of corner cases to make sure it doesn't get stuck here with
> hiararchical drivers/device getting removed while something else is
> probing them at the same time.

Oh, OK. I'll keep that in mind when sending out v2 of these patches.

Best regards
Thomas

> -Daniel
> 
>> Best regards
>> Thomas
>>
>>>
>>> Cheers, Daniel
>>>
>>>> ---
>>>>  drivers/gpu/drm/Kconfig        |   6 ++
>>>>  drivers/gpu/drm/Makefile       |   1 +
>>>>  drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
>>>>  include/drm/drm_fb_helper.h    |  18 ++++-
>>>>  include/drm/drm_platform.h     |  42 ++++++++++++
>>>>  5 files changed, 184 insertions(+), 1 deletion(-)
>>>>  create mode 100644 drivers/gpu/drm/drm_platform.c
>>>>  create mode 100644 include/drm/drm_platform.h
>>>>
>>>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>>>> index c4fd57d8b717..e9d6892f9d38 100644
>>>> --- a/drivers/gpu/drm/Kconfig
>>>> +++ b/drivers/gpu/drm/Kconfig
>>>> @@ -229,6 +229,12 @@ config DRM_SCHED
>>>>      tristate
>>>>      depends on DRM
>>>>
>>>> +config DRM_PLATFORM_HELPER
>>>> +    bool
>>>> +    depends on DRM
>>>> +    help
>>>> +      Helpers for DRM platform devices
>>>> +
>>>>  source "drivers/gpu/drm/i2c/Kconfig"
>>>>
>>>>  source "drivers/gpu/drm/arm/Kconfig"
>>>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>>>> index 2c0e5a7e5953..8ceb21d0770a 100644
>>>> --- a/drivers/gpu/drm/Makefile
>>>> +++ b/drivers/gpu/drm/Makefile
>>>> @@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>>>>  drm-$(CONFIG_PCI) += drm_pci.o
>>>>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
>>>>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
>>>> +drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
>>>>
>>>>  drm_vram_helper-y := drm_gem_vram_helper.o
>>>>  obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
>>>> diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
>>>> new file mode 100644
>>>> index 000000000000..09a2f2a31aa5
>>>> --- /dev/null
>>>> +++ b/drivers/gpu/drm/drm_platform.c
>>>> @@ -0,0 +1,118 @@
>>>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>>>> +
>>>> +#include <linux/mutex.h>
>>>> +#include <linux/slab.h>
>>>> +
>>>> +#include <drm/drm_drv.h>
>>>> +#include <drm/drm_managed.h>
>>>> +#include <drm/drm_platform.h>
>>>> +
>>>> +static LIST_HEAD(drm_apertures);
>>>> +
>>>> +static DEFINE_MUTEX(drm_apertures_lock);
>>>> +
>>>> +static bool overlap(resource_size_t base1, resource_size_t end1,
>>>> +                resource_size_t base2, resource_size_t end2)
>>>> +{
>>>> +    return (base1 < end2) && (end1 > base2);
>>>> +}
>>>> +
>>>> +static struct drm_aperture *
>>>> +drm_aperture_acquire(struct drm_device *dev,
>>>> +                 resource_size_t base, resource_size_t size,
>>>> +                 const struct drm_aperture_funcs *funcs)
>>>> +{
>>>> +    size_t end = base + size;
>>>> +    struct list_head *pos;
>>>> +    struct drm_aperture *ap;
>>>> +
>>>> +    mutex_lock(&drm_apertures_lock);
>>>> +
>>>> +    list_for_each(pos, &drm_apertures) {
>>>> +            ap = container_of(pos, struct drm_aperture, lh);
>>>> +            if (overlap(base, end, ap->base, ap->base + ap->size))
>>>> +                    return ERR_PTR(-EBUSY);
>>>> +    }
>>>> +
>>>> +    ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
>>>> +    if (!ap)
>>>> +            return ERR_PTR(-ENOMEM);
>>>> +
>>>> +    ap->dev = dev;
>>>> +    ap->base = base;
>>>> +    ap->size = size;
>>>> +    ap->funcs = funcs;
>>>> +    INIT_LIST_HEAD(&ap->lh);
>>>> +
>>>> +    list_add(&ap->lh, &drm_apertures);
>>>> +
>>>> +    mutex_unlock(&drm_apertures_lock);
>>>> +
>>>> +    return ap;
>>>> +}
>>>> +
>>>> +static void drm_aperture_release(struct drm_aperture *ap)
>>>> +{
>>>> +    bool kicked_out = ap->kicked_out;
>>>> +
>>>> +    if (!kicked_out)
>>>> +            mutex_lock(&drm_apertures_lock);
>>>> +
>>>> +    list_del(&ap->lh);
>>>> +    if (ap->funcs->release)
>>>> +            ap->funcs->release(ap);
>>>> +
>>>> +    if (!kicked_out)
>>>> +            mutex_unlock(&drm_apertures_lock);
>>>> +}
>>>> +
>>>> +static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
>>>> +{
>>>> +    struct drm_aperture *ap = ptr;
>>>> +
>>>> +    drm_aperture_release(ap);
>>>> +}
>>>> +
>>>> +struct drm_aperture *
>>>> +drmm_aperture_acquire(struct drm_device *dev,
>>>> +                  resource_size_t base, resource_size_t size,
>>>> +                  const struct drm_aperture_funcs *funcs)
>>>> +{
>>>> +    struct drm_aperture *ap;
>>>> +    int ret;
>>>> +
>>>> +    ap = drm_aperture_acquire(dev, base, size, funcs);
>>>> +    if (IS_ERR(ap))
>>>> +            return ap;
>>>> +    ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
>>>> +    if (ret)
>>>> +            return ERR_PTR(ret);
>>>> +
>>>> +    return ap;
>>>> +}
>>>> +EXPORT_SYMBOL(drmm_aperture_acquire);
>>>> +
>>>> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
>>>> +{
>>>> +    resource_size_t end = base + size;
>>>> +    struct list_head *pos, *n;
>>>> +
>>>> +    mutex_lock(&drm_apertures_lock);
>>>> +
>>>> +    list_for_each_safe(pos, n, &drm_apertures) {
>>>> +            struct drm_aperture *ap =
>>>> +                    container_of(pos, struct drm_aperture, lh);
>>>> +
>>>> +            if (!overlap(base, end, ap->base, ap->base + ap->size))
>>>> +                    continue;
>>>> +
>>>> +            ap->kicked_out = true;
>>>> +            if (ap->funcs->kickout)
>>>> +                    ap->funcs->kickout(ap);
>>>> +            else
>>>> +                    drm_dev_put(ap->dev);
>>>> +    }
>>>> +
>>>> +    mutex_unlock(&drm_apertures_lock);
>>>> +}
>>>> +EXPORT_SYMBOL(drm_kickout_apertures_at);
>>>> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
>>>> index 306aa3a60be9..a919b78b1961 100644
>>>> --- a/include/drm/drm_fb_helper.h
>>>> +++ b/include/drm/drm_fb_helper.h
>>>> @@ -35,7 +35,9 @@ struct drm_fb_helper;
>>>>  #include <drm/drm_client.h>
>>>>  #include <drm/drm_crtc.h>
>>>>  #include <drm/drm_device.h>
>>>> +#include <drm/drm_platform.h>
>>>>  #include <linux/kgdb.h>
>>>> +#include <linux/pci.h>
>>>>  #include <linux/vgaarb.h>
>>>>
>>>>  enum mode_set_atomic {
>>>> @@ -465,6 +467,11 @@ static inline int
>>>>  drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
>>>>                                            const char *name, bool primary)
>>>>  {
>>>> +    int i;
>>>> +
>>>> +    for (i = 0; i < a->count; ++i)
>>>> +            drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
>>>> +
>>>>  #if IS_REACHABLE(CONFIG_FB)
>>>>      return remove_conflicting_framebuffers(a, name, primary);
>>>>  #else
>>>> @@ -487,7 +494,16 @@ static inline int
>>>>  drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
>>>>                                                const char *name)
>>>>  {
>>>> -    int ret = 0;
>>>> +    resource_size_t base, size;
>>>> +    int bar, ret = 0;
>>>> +
>>>> +    for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
>>>> +            if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
>>>> +                    continue;
>>>> +            base = pci_resource_start(pdev, bar);
>>>> +            size = pci_resource_len(pdev, bar);
>>>> +            drm_kickout_apertures_at(base, size);
>>>> +    }
>>>>
>>>>      /*
>>>>       * WARNING: Apparently we must kick fbdev drivers before vgacon,
>>>> diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
>>>> new file mode 100644
>>>> index 000000000000..475e88ee1fbd
>>>> --- /dev/null
>>>> +++ b/include/drm/drm_platform.h
>>>> @@ -0,0 +1,42 @@
>>>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>>>> +
>>>> +#ifndef _DRM_PLATFORM_H_
>>>> +#define _DRM_PLATFORM_H_
>>>> +
>>>> +#include <linux/list.h>
>>>> +#include <linux/types.h>
>>>> +
>>>> +struct drm_aperture;
>>>> +struct drm_device;
>>>> +
>>>> +struct drm_aperture_funcs {
>>>> +    void (*kickout)(struct drm_aperture *ap);
>>>> +    void (*release)(struct drm_aperture *ap);
>>>> +};
>>>> +
>>>> +struct drm_aperture {
>>>> +    struct drm_device *dev;
>>>> +    resource_size_t base;
>>>> +    resource_size_t size;
>>>> +
>>>> +    const struct drm_aperture_funcs *funcs;
>>>> +
>>>> +    struct list_head lh;
>>>> +    bool kicked_out;
>>>> +};
>>>> +
>>>> +struct drm_aperture *
>>>> +drmm_aperture_acquire(struct drm_device *dev,
>>>> +                  resource_size_t base, resource_size_t size,
>>>> +                  const struct drm_aperture_funcs *funcs);
>>>> +
>>>> +#if defined (CONFIG_DRM_PLATFORM_HELPER)
>>>> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
>>>> +#else
>>>> +static inline void
>>>> +drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
>>>> +{
>>>> +}
>>>> +#endif
>>>> +
>>>> +#endif
>>>> --
>>>> 2.27.0
>>>>
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Felix Imendörffer
>>
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 8/9] drm: Add infrastructure for platform devices

[Thomas Zimmermann]

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Hi

Am 29.06.20 um 11:27 schrieb Daniel Vetter:
> On Thu, Jun 25, 2020 at 02:00:10PM +0200, Thomas Zimmermann wrote:
>> Platform devices might operate on firmware framebuffers, such as VESA or
>> EFI. Before a native driver for the graphics hardware can take over the
>> device, it has to remove any platform driver that operates on the firmware
>> framebuffer. Platform helpers provide the infrastructure for platform
>> drivers to acquire firmware framebuffers, and for native drivers to remove
>> them lateron.
>>
>> It works similar to the related fbdev mechanism. During initialization, the
>> platform driver acquires the firmware framebuffer's I/O memory and provides
>> a callback to be removed. The native driver later uses this inforamtion to
>> remove any platform driver for it's framebuffer I/O memory.
>>
>> The platform helper's removal code is integrated into the existing code for
>> removing conflicting fraembuffers, so native drivers use it automatically.
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> 
> I have some ideas for how to do this a notch cleaner in the next patch.
> Maybe best to discuss the actual implmenentation stuff there.
> 
> Aside from that usual nits:
> - kerneldoc for these please, pulled into drm-kms.rst.

Any specific reason for drm-kms?

The aperture helpers are used to manage ownership of memory and most
drivers begin with drm_fb_helper_remove_conflicting_framebuffers(). It
seems more approprite to put this into drm-internals as part of the
driver initialization.

Best regards
Thomas

> - naming isn't super ocd with drm_platform.c but that prefix not used, but
>   I also don't have better ideas.
> - I think the functions from drm_fb_helper.h for removing other
>   framebuffers should be moved here, and function name prefix adjusted
>   acoordingly
> 
> I'm wondering about the locking and deadlock potential here, is lockdep
> all happy with this?
> 
> Cheers, Daniel
> 
>> ---
>>  drivers/gpu/drm/Kconfig        |   6 ++
>>  drivers/gpu/drm/Makefile       |   1 +
>>  drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
>>  include/drm/drm_fb_helper.h    |  18 ++++-
>>  include/drm/drm_platform.h     |  42 ++++++++++++
>>  5 files changed, 184 insertions(+), 1 deletion(-)
>>  create mode 100644 drivers/gpu/drm/drm_platform.c
>>  create mode 100644 include/drm/drm_platform.h
>>
>> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
>> index c4fd57d8b717..e9d6892f9d38 100644
>> --- a/drivers/gpu/drm/Kconfig
>> +++ b/drivers/gpu/drm/Kconfig
>> @@ -229,6 +229,12 @@ config DRM_SCHED
>>  	tristate
>>  	depends on DRM
>>  
>> +config DRM_PLATFORM_HELPER
>> +	bool
>> +	depends on DRM
>> +	help
>> +	  Helpers for DRM platform devices
>> +
>>  source "drivers/gpu/drm/i2c/Kconfig"
>>  
>>  source "drivers/gpu/drm/arm/Kconfig"
>> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
>> index 2c0e5a7e5953..8ceb21d0770a 100644
>> --- a/drivers/gpu/drm/Makefile
>> +++ b/drivers/gpu/drm/Makefile
>> @@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>>  drm-$(CONFIG_PCI) += drm_pci.o
>>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
>>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
>> +drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
>>  
>>  drm_vram_helper-y := drm_gem_vram_helper.o
>>  obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
>> diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
>> new file mode 100644
>> index 000000000000..09a2f2a31aa5
>> --- /dev/null
>> +++ b/drivers/gpu/drm/drm_platform.c
>> @@ -0,0 +1,118 @@
>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>> +
>> +#include <linux/mutex.h>
>> +#include <linux/slab.h>
>> +
>> +#include <drm/drm_drv.h>
>> +#include <drm/drm_managed.h>
>> +#include <drm/drm_platform.h>
>> +
>> +static LIST_HEAD(drm_apertures);
>> +
>> +static DEFINE_MUTEX(drm_apertures_lock);
>> +
>> +static bool overlap(resource_size_t base1, resource_size_t end1,
>> +		    resource_size_t base2, resource_size_t end2)
>> +{
>> +	return (base1 < end2) && (end1 > base2);
>> +}
>> +
>> +static struct drm_aperture *
>> +drm_aperture_acquire(struct drm_device *dev,
>> +		     resource_size_t base, resource_size_t size,
>> +		     const struct drm_aperture_funcs *funcs)
>> +{
>> +	size_t end = base + size;
>> +	struct list_head *pos;
>> +	struct drm_aperture *ap;
>> +
>> +	mutex_lock(&drm_apertures_lock);
>> +
>> +	list_for_each(pos, &drm_apertures) {
>> +		ap = container_of(pos, struct drm_aperture, lh);
>> +		if (overlap(base, end, ap->base, ap->base + ap->size))
>> +			return ERR_PTR(-EBUSY);
>> +	}
>> +
>> +	ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
>> +	if (!ap)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	ap->dev = dev;
>> +	ap->base = base;
>> +	ap->size = size;
>> +	ap->funcs = funcs;
>> +	INIT_LIST_HEAD(&ap->lh);
>> +
>> +	list_add(&ap->lh, &drm_apertures);
>> +
>> +	mutex_unlock(&drm_apertures_lock);
>> +
>> +	return ap;
>> +}
>> +
>> +static void drm_aperture_release(struct drm_aperture *ap)
>> +{
>> +	bool kicked_out = ap->kicked_out;
>> +
>> +	if (!kicked_out)
>> +		mutex_lock(&drm_apertures_lock);
>> +
>> +	list_del(&ap->lh);
>> +	if (ap->funcs->release)
>> +		ap->funcs->release(ap);
>> +
>> +	if (!kicked_out)
>> +		mutex_unlock(&drm_apertures_lock);
>> +}
>> +
>> +static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
>> +{
>> +	struct drm_aperture *ap = ptr;
>> +
>> +	drm_aperture_release(ap);
>> +}
>> +
>> +struct drm_aperture *
>> +drmm_aperture_acquire(struct drm_device *dev,
>> +		      resource_size_t base, resource_size_t size,
>> +		      const struct drm_aperture_funcs *funcs)
>> +{
>> +	struct drm_aperture *ap;
>> +	int ret;
>> +
>> +	ap = drm_aperture_acquire(dev, base, size, funcs);
>> +	if (IS_ERR(ap))
>> +		return ap;
>> +	ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
>> +	if (ret)
>> +		return ERR_PTR(ret);
>> +
>> +	return ap;
>> +}
>> +EXPORT_SYMBOL(drmm_aperture_acquire);
>> +
>> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
>> +{
>> +	resource_size_t end = base + size;
>> +	struct list_head *pos, *n;
>> +
>> +	mutex_lock(&drm_apertures_lock);
>> +
>> +	list_for_each_safe(pos, n, &drm_apertures) {
>> +		struct drm_aperture *ap =
>> +			container_of(pos, struct drm_aperture, lh);
>> +
>> +		if (!overlap(base, end, ap->base, ap->base + ap->size))
>> +			continue;
>> +
>> +		ap->kicked_out = true;
>> +		if (ap->funcs->kickout)
>> +			ap->funcs->kickout(ap);
>> +		else
>> +			drm_dev_put(ap->dev);
>> +	}
>> +
>> +	mutex_unlock(&drm_apertures_lock);
>> +}
>> +EXPORT_SYMBOL(drm_kickout_apertures_at);
>> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
>> index 306aa3a60be9..a919b78b1961 100644
>> --- a/include/drm/drm_fb_helper.h
>> +++ b/include/drm/drm_fb_helper.h
>> @@ -35,7 +35,9 @@ struct drm_fb_helper;
>>  #include <drm/drm_client.h>
>>  #include <drm/drm_crtc.h>
>>  #include <drm/drm_device.h>
>> +#include <drm/drm_platform.h>
>>  #include <linux/kgdb.h>
>> +#include <linux/pci.h>
>>  #include <linux/vgaarb.h>
>>  
>>  enum mode_set_atomic {
>> @@ -465,6 +467,11 @@ static inline int
>>  drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
>>  					      const char *name, bool primary)
>>  {
>> +	int i;
>> +
>> +	for (i = 0; i < a->count; ++i)
>> +		drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
>> +
>>  #if IS_REACHABLE(CONFIG_FB)
>>  	return remove_conflicting_framebuffers(a, name, primary);
>>  #else
>> @@ -487,7 +494,16 @@ static inline int
>>  drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
>>  						  const char *name)
>>  {
>> -	int ret = 0;
>> +	resource_size_t base, size;
>> +	int bar, ret = 0;
>> +
>> +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
>> +		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
>> +			continue;
>> +		base = pci_resource_start(pdev, bar);
>> +		size = pci_resource_len(pdev, bar);
>> +		drm_kickout_apertures_at(base, size);
>> +	}
>>  
>>  	/*
>>  	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
>> diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
>> new file mode 100644
>> index 000000000000..475e88ee1fbd
>> --- /dev/null
>> +++ b/include/drm/drm_platform.h
>> @@ -0,0 +1,42 @@
>> +// SPDX-License-Identifier: GPL-2.0 OR MIT
>> +
>> +#ifndef _DRM_PLATFORM_H_
>> +#define _DRM_PLATFORM_H_
>> +
>> +#include <linux/list.h>
>> +#include <linux/types.h>
>> +
>> +struct drm_aperture;
>> +struct drm_device;
>> +
>> +struct drm_aperture_funcs {
>> +	void (*kickout)(struct drm_aperture *ap);
>> +	void (*release)(struct drm_aperture *ap);
>> +};
>> +
>> +struct drm_aperture {
>> +	struct drm_device *dev;
>> +	resource_size_t base;
>> +	resource_size_t size;
>> +
>> +	const struct drm_aperture_funcs *funcs;
>> +
>> +	struct list_head lh;
>> +	bool kicked_out;
>> +};
>> +
>> +struct drm_aperture *
>> +drmm_aperture_acquire(struct drm_device *dev,
>> +		      resource_size_t base, resource_size_t size,
>> +		      const struct drm_aperture_funcs *funcs);
>> +
>> +#if defined (CONFIG_DRM_PLATFORM_HELPER)
>> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
>> +#else
>> +static inline void
>> +drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
>> +{
>> +}
>> +#endif
>> +
>> +#endif
>> -- 
>> 2.27.0
>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [PATCH 8/9] drm: Add infrastructure for platform devices

[Daniel Vetter]

On Tue, Sep 29, 2020 at 10:59:10AM +0200, Thomas Zimmermann wrote:
> Hi
> 
> Am 29.06.20 um 11:27 schrieb Daniel Vetter:
> > On Thu, Jun 25, 2020 at 02:00:10PM +0200, Thomas Zimmermann wrote:
> >> Platform devices might operate on firmware framebuffers, such as VESA or
> >> EFI. Before a native driver for the graphics hardware can take over the
> >> device, it has to remove any platform driver that operates on the firmware
> >> framebuffer. Platform helpers provide the infrastructure for platform
> >> drivers to acquire firmware framebuffers, and for native drivers to remove
> >> them lateron.
> >>
> >> It works similar to the related fbdev mechanism. During initialization, the
> >> platform driver acquires the firmware framebuffer's I/O memory and provides
> >> a callback to be removed. The native driver later uses this inforamtion to
> >> remove any platform driver for it's framebuffer I/O memory.
> >>
> >> The platform helper's removal code is integrated into the existing code for
> >> removing conflicting fraembuffers, so native drivers use it automatically.
> >>
> >> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> > 
> > I have some ideas for how to do this a notch cleaner in the next patch.
> > Maybe best to discuss the actual implmenentation stuff there.
> > 
> > Aside from that usual nits:
> > - kerneldoc for these please, pulled into drm-kms.rst.
> 
> Any specific reason for drm-kms?
> 
> The aperture helpers are used to manage ownership of memory and most
> drivers begin with drm_fb_helper_remove_conflicting_framebuffers(). It
> seems more approprite to put this into drm-internals as part of the
> driver initialization.

Simple because the only reason you might want to use this is for display.
In no other case do we load a firmware driver to make hw semi-useable.
Putting it where people might look for it and all that.
-Daniel

> 
> Best regards
> Thomas
> 
> > - naming isn't super ocd with drm_platform.c but that prefix not used, but
> >   I also don't have better ideas.
> > - I think the functions from drm_fb_helper.h for removing other
> >   framebuffers should be moved here, and function name prefix adjusted
> >   acoordingly
> > 
> > I'm wondering about the locking and deadlock potential here, is lockdep
> > all happy with this?
> > 
> > Cheers, Daniel
> > 
> >> ---
> >>  drivers/gpu/drm/Kconfig        |   6 ++
> >>  drivers/gpu/drm/Makefile       |   1 +
> >>  drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
> >>  include/drm/drm_fb_helper.h    |  18 ++++-
> >>  include/drm/drm_platform.h     |  42 ++++++++++++
> >>  5 files changed, 184 insertions(+), 1 deletion(-)
> >>  create mode 100644 drivers/gpu/drm/drm_platform.c
> >>  create mode 100644 include/drm/drm_platform.h
> >>
> >> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> >> index c4fd57d8b717..e9d6892f9d38 100644
> >> --- a/drivers/gpu/drm/Kconfig
> >> +++ b/drivers/gpu/drm/Kconfig
> >> @@ -229,6 +229,12 @@ config DRM_SCHED
> >>  	tristate
> >>  	depends on DRM
> >>  
> >> +config DRM_PLATFORM_HELPER
> >> +	bool
> >> +	depends on DRM
> >> +	help
> >> +	  Helpers for DRM platform devices
> >> +
> >>  source "drivers/gpu/drm/i2c/Kconfig"
> >>  
> >>  source "drivers/gpu/drm/arm/Kconfig"
> >> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> >> index 2c0e5a7e5953..8ceb21d0770a 100644
> >> --- a/drivers/gpu/drm/Makefile
> >> +++ b/drivers/gpu/drm/Makefile
> >> @@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
> >>  drm-$(CONFIG_PCI) += drm_pci.o
> >>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
> >>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> >> +drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
> >>  
> >>  drm_vram_helper-y := drm_gem_vram_helper.o
> >>  obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
> >> diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
> >> new file mode 100644
> >> index 000000000000..09a2f2a31aa5
> >> --- /dev/null
> >> +++ b/drivers/gpu/drm/drm_platform.c
> >> @@ -0,0 +1,118 @@
> >> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> >> +
> >> +#include <linux/mutex.h>
> >> +#include <linux/slab.h>
> >> +
> >> +#include <drm/drm_drv.h>
> >> +#include <drm/drm_managed.h>
> >> +#include <drm/drm_platform.h>
> >> +
> >> +static LIST_HEAD(drm_apertures);
> >> +
> >> +static DEFINE_MUTEX(drm_apertures_lock);
> >> +
> >> +static bool overlap(resource_size_t base1, resource_size_t end1,
> >> +		    resource_size_t base2, resource_size_t end2)
> >> +{
> >> +	return (base1 < end2) && (end1 > base2);
> >> +}
> >> +
> >> +static struct drm_aperture *
> >> +drm_aperture_acquire(struct drm_device *dev,
> >> +		     resource_size_t base, resource_size_t size,
> >> +		     const struct drm_aperture_funcs *funcs)
> >> +{
> >> +	size_t end = base + size;
> >> +	struct list_head *pos;
> >> +	struct drm_aperture *ap;
> >> +
> >> +	mutex_lock(&drm_apertures_lock);
> >> +
> >> +	list_for_each(pos, &drm_apertures) {
> >> +		ap = container_of(pos, struct drm_aperture, lh);
> >> +		if (overlap(base, end, ap->base, ap->base + ap->size))
> >> +			return ERR_PTR(-EBUSY);
> >> +	}
> >> +
> >> +	ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);
> >> +	if (!ap)
> >> +		return ERR_PTR(-ENOMEM);
> >> +
> >> +	ap->dev = dev;
> >> +	ap->base = base;
> >> +	ap->size = size;
> >> +	ap->funcs = funcs;
> >> +	INIT_LIST_HEAD(&ap->lh);
> >> +
> >> +	list_add(&ap->lh, &drm_apertures);
> >> +
> >> +	mutex_unlock(&drm_apertures_lock);
> >> +
> >> +	return ap;
> >> +}
> >> +
> >> +static void drm_aperture_release(struct drm_aperture *ap)
> >> +{
> >> +	bool kicked_out = ap->kicked_out;
> >> +
> >> +	if (!kicked_out)
> >> +		mutex_lock(&drm_apertures_lock);
> >> +
> >> +	list_del(&ap->lh);
> >> +	if (ap->funcs->release)
> >> +		ap->funcs->release(ap);
> >> +
> >> +	if (!kicked_out)
> >> +		mutex_unlock(&drm_apertures_lock);
> >> +}
> >> +
> >> +static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
> >> +{
> >> +	struct drm_aperture *ap = ptr;
> >> +
> >> +	drm_aperture_release(ap);
> >> +}
> >> +
> >> +struct drm_aperture *
> >> +drmm_aperture_acquire(struct drm_device *dev,
> >> +		      resource_size_t base, resource_size_t size,
> >> +		      const struct drm_aperture_funcs *funcs)
> >> +{
> >> +	struct drm_aperture *ap;
> >> +	int ret;
> >> +
> >> +	ap = drm_aperture_acquire(dev, base, size, funcs);
> >> +	if (IS_ERR(ap))
> >> +		return ap;
> >> +	ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
> >> +	if (ret)
> >> +		return ERR_PTR(ret);
> >> +
> >> +	return ap;
> >> +}
> >> +EXPORT_SYMBOL(drmm_aperture_acquire);
> >> +
> >> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> >> +{
> >> +	resource_size_t end = base + size;
> >> +	struct list_head *pos, *n;
> >> +
> >> +	mutex_lock(&drm_apertures_lock);
> >> +
> >> +	list_for_each_safe(pos, n, &drm_apertures) {
> >> +		struct drm_aperture *ap =
> >> +			container_of(pos, struct drm_aperture, lh);
> >> +
> >> +		if (!overlap(base, end, ap->base, ap->base + ap->size))
> >> +			continue;
> >> +
> >> +		ap->kicked_out = true;
> >> +		if (ap->funcs->kickout)
> >> +			ap->funcs->kickout(ap);
> >> +		else
> >> +			drm_dev_put(ap->dev);
> >> +	}
> >> +
> >> +	mutex_unlock(&drm_apertures_lock);
> >> +}
> >> +EXPORT_SYMBOL(drm_kickout_apertures_at);
> >> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> >> index 306aa3a60be9..a919b78b1961 100644
> >> --- a/include/drm/drm_fb_helper.h
> >> +++ b/include/drm/drm_fb_helper.h
> >> @@ -35,7 +35,9 @@ struct drm_fb_helper;
> >>  #include <drm/drm_client.h>
> >>  #include <drm/drm_crtc.h>
> >>  #include <drm/drm_device.h>
> >> +#include <drm/drm_platform.h>
> >>  #include <linux/kgdb.h>
> >> +#include <linux/pci.h>
> >>  #include <linux/vgaarb.h>
> >>  
> >>  enum mode_set_atomic {
> >> @@ -465,6 +467,11 @@ static inline int
> >>  drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
> >>  					      const char *name, bool primary)
> >>  {
> >> +	int i;
> >> +
> >> +	for (i = 0; i < a->count; ++i)
> >> +		drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
> >> +
> >>  #if IS_REACHABLE(CONFIG_FB)
> >>  	return remove_conflicting_framebuffers(a, name, primary);
> >>  #else
> >> @@ -487,7 +494,16 @@ static inline int
> >>  drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
> >>  						  const char *name)
> >>  {
> >> -	int ret = 0;
> >> +	resource_size_t base, size;
> >> +	int bar, ret = 0;
> >> +
> >> +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> >> +		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> >> +			continue;
> >> +		base = pci_resource_start(pdev, bar);
> >> +		size = pci_resource_len(pdev, bar);
> >> +		drm_kickout_apertures_at(base, size);
> >> +	}
> >>  
> >>  	/*
> >>  	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
> >> diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
> >> new file mode 100644
> >> index 000000000000..475e88ee1fbd
> >> --- /dev/null
> >> +++ b/include/drm/drm_platform.h
> >> @@ -0,0 +1,42 @@
> >> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> >> +
> >> +#ifndef _DRM_PLATFORM_H_
> >> +#define _DRM_PLATFORM_H_
> >> +
> >> +#include <linux/list.h>
> >> +#include <linux/types.h>
> >> +
> >> +struct drm_aperture;
> >> +struct drm_device;
> >> +
> >> +struct drm_aperture_funcs {
> >> +	void (*kickout)(struct drm_aperture *ap);
> >> +	void (*release)(struct drm_aperture *ap);
> >> +};
> >> +
> >> +struct drm_aperture {
> >> +	struct drm_device *dev;
> >> +	resource_size_t base;
> >> +	resource_size_t size;
> >> +
> >> +	const struct drm_aperture_funcs *funcs;
> >> +
> >> +	struct list_head lh;
> >> +	bool kicked_out;
> >> +};
> >> +
> >> +struct drm_aperture *
> >> +drmm_aperture_acquire(struct drm_device *dev,
> >> +		      resource_size_t base, resource_size_t size,
> >> +		      const struct drm_aperture_funcs *funcs);
> >> +
> >> +#if defined (CONFIG_DRM_PLATFORM_HELPER)
> >> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
> >> +#else
> >> +static inline void
> >> +drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> >> +{
> >> +}
> >> +#endif
> >> +
> >> +#endif
> >> -- 
> >> 2.27.0
> >>
> > 
> 
> -- 
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
> 




-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: [PATCH 8/9] drm: Add infrastructure for platform devices

[Daniel Vetter]

On Thu, Jun 25, 2020 at 02:00:10PM +0200, Thomas Zimmermann wrote:
> Platform devices might operate on firmware framebuffers, such as VESA or
> EFI. Before a native driver for the graphics hardware can take over the
> device, it has to remove any platform driver that operates on the firmware
> framebuffer. Platform helpers provide the infrastructure for platform
> drivers to acquire firmware framebuffers, and for native drivers to remove
> them lateron.
> 
> It works similar to the related fbdev mechanism. During initialization, the
> platform driver acquires the firmware framebuffer's I/O memory and provides
> a callback to be removed. The native driver later uses this inforamtion to
> remove any platform driver for it's framebuffer I/O memory.
> 
> The platform helper's removal code is integrated into the existing code for
> removing conflicting fraembuffers, so native drivers use it automatically.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/Kconfig        |   6 ++
>  drivers/gpu/drm/Makefile       |   1 +
>  drivers/gpu/drm/drm_platform.c | 118 +++++++++++++++++++++++++++++++++
>  include/drm/drm_fb_helper.h    |  18 ++++-
>  include/drm/drm_platform.h     |  42 ++++++++++++
>  5 files changed, 184 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/drm_platform.c
>  create mode 100644 include/drm/drm_platform.h
> 
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index c4fd57d8b717..e9d6892f9d38 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -229,6 +229,12 @@ config DRM_SCHED
>  	tristate
>  	depends on DRM
>  
> +config DRM_PLATFORM_HELPER
> +	bool
> +	depends on DRM
> +	help
> +	  Helpers for DRM platform devices
> +
>  source "drivers/gpu/drm/i2c/Kconfig"
>  
>  source "drivers/gpu/drm/arm/Kconfig"
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 2c0e5a7e5953..8ceb21d0770a 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -32,6 +32,7 @@ drm-$(CONFIG_AGP) += drm_agpsupport.o
>  drm-$(CONFIG_PCI) += drm_pci.o
>  drm-$(CONFIG_DEBUG_FS) += drm_debugfs.o drm_debugfs_crc.o
>  drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
> +drm-$(CONFIG_DRM_PLATFORM_HELPER) += drm_platform.o
>  
>  drm_vram_helper-y := drm_gem_vram_helper.o
>  obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
> diff --git a/drivers/gpu/drm/drm_platform.c b/drivers/gpu/drm/drm_platform.c
> new file mode 100644
> index 000000000000..09a2f2a31aa5
> --- /dev/null
> +++ b/drivers/gpu/drm/drm_platform.c
> @@ -0,0 +1,118 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +#include <linux/mutex.h>
> +#include <linux/slab.h>
> +
> +#include <drm/drm_drv.h>
> +#include <drm/drm_managed.h>
> +#include <drm/drm_platform.h>
> +
> +static LIST_HEAD(drm_apertures);
> +
> +static DEFINE_MUTEX(drm_apertures_lock);
> +
> +static bool overlap(resource_size_t base1, resource_size_t end1,
> +		    resource_size_t base2, resource_size_t end2)
> +{
> +	return (base1 < end2) && (end1 > base2);
> +}
> +
> +static struct drm_aperture *
> +drm_aperture_acquire(struct drm_device *dev,
> +		     resource_size_t base, resource_size_t size,
> +		     const struct drm_aperture_funcs *funcs)
> +{
> +	size_t end = base + size;
> +	struct list_head *pos;
> +	struct drm_aperture *ap;
> +
> +	mutex_lock(&drm_apertures_lock);
> +
> +	list_for_each(pos, &drm_apertures) {
> +		ap = container_of(pos, struct drm_aperture, lh);
> +		if (overlap(base, end, ap->base, ap->base + ap->size))
> +			return ERR_PTR(-EBUSY);
> +	}
> +
> +	ap = drmm_kzalloc(dev, sizeof(*ap), GFP_KERNEL);

One technical thing here, but that'll be even more clear once the next
patch is using the driver core detach function: This should be devm_ not
drmm_ (both here and below) because it's tied to the lifetime of the
physical device and the driver binding.

Once the driver is unbound, even if drm_device keeps surviving because
userspace is still holding references, there's no point in trying to
unbind it again. So auto-cleanup using devm_ is the right thing here imo.

And with the change to the driver model unbind you will have a struct
device * pointer, so this all works out.
-Daniel

> +	if (!ap)
> +		return ERR_PTR(-ENOMEM);
> +
> +	ap->dev = dev;
> +	ap->base = base;
> +	ap->size = size;
> +	ap->funcs = funcs;
> +	INIT_LIST_HEAD(&ap->lh);
> +
> +	list_add(&ap->lh, &drm_apertures);
> +
> +	mutex_unlock(&drm_apertures_lock);
> +
> +	return ap;
> +}
> +
> +static void drm_aperture_release(struct drm_aperture *ap)
> +{
> +	bool kicked_out = ap->kicked_out;
> +
> +	if (!kicked_out)
> +		mutex_lock(&drm_apertures_lock);
> +
> +	list_del(&ap->lh);
> +	if (ap->funcs->release)
> +		ap->funcs->release(ap);
> +
> +	if (!kicked_out)
> +		mutex_unlock(&drm_apertures_lock);
> +}
> +
> +static void drm_aperture_acquire_release(struct drm_device *dev, void *ptr)
> +{
> +	struct drm_aperture *ap = ptr;
> +
> +	drm_aperture_release(ap);
> +}
> +
> +struct drm_aperture *
> +drmm_aperture_acquire(struct drm_device *dev,
> +		      resource_size_t base, resource_size_t size,
> +		      const struct drm_aperture_funcs *funcs)
> +{
> +	struct drm_aperture *ap;
> +	int ret;
> +
> +	ap = drm_aperture_acquire(dev, base, size, funcs);
> +	if (IS_ERR(ap))
> +		return ap;
> +	ret = drmm_add_action_or_reset(dev, drm_aperture_acquire_release, ap);
> +	if (ret)
> +		return ERR_PTR(ret);
> +
> +	return ap;
> +}
> +EXPORT_SYMBOL(drmm_aperture_acquire);
> +
> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> +{
> +	resource_size_t end = base + size;
> +	struct list_head *pos, *n;
> +
> +	mutex_lock(&drm_apertures_lock);
> +
> +	list_for_each_safe(pos, n, &drm_apertures) {
> +		struct drm_aperture *ap =
> +			container_of(pos, struct drm_aperture, lh);
> +
> +		if (!overlap(base, end, ap->base, ap->base + ap->size))
> +			continue;
> +
> +		ap->kicked_out = true;
> +		if (ap->funcs->kickout)
> +			ap->funcs->kickout(ap);
> +		else
> +			drm_dev_put(ap->dev);
> +	}
> +
> +	mutex_unlock(&drm_apertures_lock);
> +}
> +EXPORT_SYMBOL(drm_kickout_apertures_at);
> diff --git a/include/drm/drm_fb_helper.h b/include/drm/drm_fb_helper.h
> index 306aa3a60be9..a919b78b1961 100644
> --- a/include/drm/drm_fb_helper.h
> +++ b/include/drm/drm_fb_helper.h
> @@ -35,7 +35,9 @@ struct drm_fb_helper;
>  #include <drm/drm_client.h>
>  #include <drm/drm_crtc.h>
>  #include <drm/drm_device.h>
> +#include <drm/drm_platform.h>
>  #include <linux/kgdb.h>
> +#include <linux/pci.h>
>  #include <linux/vgaarb.h>
>  
>  enum mode_set_atomic {
> @@ -465,6 +467,11 @@ static inline int
>  drm_fb_helper_remove_conflicting_framebuffers(struct apertures_struct *a,
>  					      const char *name, bool primary)
>  {
> +	int i;
> +
> +	for (i = 0; i < a->count; ++i)
> +		drm_kickout_apertures_at(a->ranges[i].base, a->ranges[i].size);
> +
>  #if IS_REACHABLE(CONFIG_FB)
>  	return remove_conflicting_framebuffers(a, name, primary);
>  #else
> @@ -487,7 +494,16 @@ static inline int
>  drm_fb_helper_remove_conflicting_pci_framebuffers(struct pci_dev *pdev,
>  						  const char *name)
>  {
> -	int ret = 0;
> +	resource_size_t base, size;
> +	int bar, ret = 0;
> +
> +	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
> +		if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM))
> +			continue;
> +		base = pci_resource_start(pdev, bar);
> +		size = pci_resource_len(pdev, bar);
> +		drm_kickout_apertures_at(base, size);
> +	}
>  
>  	/*
>  	 * WARNING: Apparently we must kick fbdev drivers before vgacon,
> diff --git a/include/drm/drm_platform.h b/include/drm/drm_platform.h
> new file mode 100644
> index 000000000000..475e88ee1fbd
> --- /dev/null
> +++ b/include/drm/drm_platform.h
> @@ -0,0 +1,42 @@
> +// SPDX-License-Identifier: GPL-2.0 OR MIT
> +
> +#ifndef _DRM_PLATFORM_H_
> +#define _DRM_PLATFORM_H_
> +
> +#include <linux/list.h>
> +#include <linux/types.h>
> +
> +struct drm_aperture;
> +struct drm_device;
> +
> +struct drm_aperture_funcs {
> +	void (*kickout)(struct drm_aperture *ap);
> +	void (*release)(struct drm_aperture *ap);
> +};
> +
> +struct drm_aperture {
> +	struct drm_device *dev;
> +	resource_size_t base;
> +	resource_size_t size;
> +
> +	const struct drm_aperture_funcs *funcs;
> +
> +	struct list_head lh;
> +	bool kicked_out;
> +};
> +
> +struct drm_aperture *
> +drmm_aperture_acquire(struct drm_device *dev,
> +		      resource_size_t base, resource_size_t size,
> +		      const struct drm_aperture_funcs *funcs);
> +
> +#if defined (CONFIG_DRM_PLATFORM_HELPER)
> +void drm_kickout_apertures_at(resource_size_t base, resource_size_t size);
> +#else
> +static inline void
> +drm_kickout_apertures_at(resource_size_t base, resource_size_t size)
> +{
> +}
> +#endif
> +
> +#endif
> -- 
> 2.27.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

[PATCH 9/9] drm/simplekms: Acquire memory aperture for framebuffer

[Thomas Zimmermann]

We register the simplekms device with the DRM platform helpers. A
native driver for the graphics hardware will kickout the simplekms
driver before taking over the device.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/Kconfig     |  1 +
 drivers/gpu/drm/tiny/simplekms.c | 94 +++++++++++++++++++++++++++++++-
 2 files changed, 92 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index 50dbde8bdcb2..a47ed337a7fe 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -33,6 +33,7 @@ config DRM_SIMPLEKMS
 	depends on DRM
 	select DRM_GEM_SHMEM_HELPER
 	select DRM_KMS_HELPER
+	select DRM_PLATFORM_HELPER
 	help
 	  DRM driver for simple platform-provided framebuffers.
 
diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
index ae5d3cbadbe8..a903a4e0100a 100644
--- a/drivers/gpu/drm/tiny/simplekms.c
+++ b/drivers/gpu/drm/tiny/simplekms.c
@@ -5,6 +5,7 @@
 #include <linux/platform_data/simplefb.h>
 #include <linux/platform_device.h>
 #include <linux/regulator/consumer.h>
+#include <linux/spinlock.h>
 
 #include <drm/drm_atomic_state_helper.h>
 #include <drm/drm_connector.h>
@@ -17,6 +18,7 @@
 #include <drm/drm_gem_shmem_helper.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_platform.h>
 #include <drm/drm_probe_helper.h>
 #include <drm/drm_simple_kms_helper.h>
 
@@ -36,6 +38,12 @@
 #define SIMPLEKMS_MODE(hd, vd)	\
 	DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
 
+/*
+ * Protects the platform device's drvdata against
+ * concurrent manipulation.
+ */
+static DEFINE_SPINLOCK(simplekms_drvdata_lock);
+
 /*
  * Helpers for simplefb
  */
@@ -211,6 +219,7 @@ struct simplekms_device {
 	unsigned int pitch;
 
 	/* memory management */
+	struct drm_aperture *aperture;
 	struct resource *mem;
 	void __iomem *screen_base;
 
@@ -224,6 +233,8 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
 	return container_of(dev, struct simplekms_device, dev);
 }
 
+static void simplekms_device_cleanup(struct simplekms_device *sdev);
+
 /*
  * Hardware
  */
@@ -514,22 +525,72 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
  * Memory management
  */
 
+static void simplekms_aperture_kickout(struct drm_aperture *ap)
+{
+	struct drm_device *dev = ap->dev;
+	struct simplekms_device *sdev = simplekms_device_of_dev(dev);
+	struct platform_device *pdev = sdev->pdev;
+
+	if (WARN_ON(!sdev->aperture))
+		return; /* BUG: driver already got kicked out */
+
+	drm_dev_unregister(dev);
+
+	sdev->aperture = NULL; /* memory is released by platform helpers */
+
+	spin_lock(&simplekms_drvdata_lock);
+	sdev = platform_get_drvdata(pdev);
+	platform_set_drvdata(pdev, NULL); /* required; see simplekms_remove() */
+	spin_unlock(&simplekms_drvdata_lock);
+
+	/*
+	 * Return if a concurrent simplekms_remove() cleans up the
+	 * device. See simplekms_remove().
+	 */
+	if (!sdev)
+		return;
+
+	/*
+	 * After the aperture has been released, there's no reason
+	 * to keep the DRM device around.
+	 */
+	simplekms_device_cleanup(sdev);
+}
+
+static const struct drm_aperture_funcs simplekms_aperture_funcs = {
+	.kickout = simplekms_aperture_kickout,
+};
+
 static int simplekms_device_init_mm(struct simplekms_device *sdev)
 {
+	struct drm_device *dev = &sdev->dev;
 	struct platform_device *pdev = sdev->pdev;
 	struct resource *mem;
+	struct drm_aperture *ap;
 	void __iomem *screen_base;
+	int ret;
 
 	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	if (!mem)
 		return -EINVAL;
 
+	ap = drmm_aperture_acquire(dev, mem->start, resource_size(mem),
+				   &simplekms_aperture_funcs);
+	if (IS_ERR(ap)) {
+		ret = PTR_ERR(ap);
+		drm_err(dev,
+			"could not acquire memory range [0x%llx:0x%llx]: "
+			"error %d\n", mem->start, mem->end, ret);
+		return ret;
+	}
+
 	screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
 				      resource_size(mem));
 	if (!screen_base)
 		return -ENOMEM;
 
 	sdev->mem = mem;
+	sdev->aperture = ap;
 	sdev->screen_base = screen_base;
 
 	return 0;
@@ -625,6 +686,9 @@ simplekms_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
 	struct drm_framebuffer *fb = state->fb;
 	void *vmap;
 
+	if (!sdev->aperture)
+		return;
+
 	vmap = drm_gem_shmem_vmap(fb->obj[0]);
 	if (!vmap)
 		return;
@@ -645,6 +709,9 @@ simplekms_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
 	struct drm_rect clip;
 	void *vmap;
 
+	if (!sdev->aperture)
+		return;
+
 	if (!drm_atomic_helper_damage_merged(old_plane_state, state, &clip))
 		return;
 
@@ -716,11 +783,12 @@ static int simplekms_device_init_modeset(struct simplekms_device *sdev)
  * Init / Cleanup
  */
 
-static void simplekms_device_cleanup(struct simplekms_device* sdev)
+static void simplekms_device_cleanup(struct simplekms_device *sdev)
 {
 	struct drm_device *dev = &sdev->dev;
 
-	drm_dev_unregister(dev);
+	if (dev->registered)
+		drm_dev_unregister(dev);
 }
 
 static struct simplekms_device *
@@ -797,7 +865,27 @@ static int simplekms_probe(struct platform_device *pdev)
 
 static int simplekms_remove(struct platform_device *pdev)
 {
-	struct simplekms_device *sdev = platform_get_drvdata(pdev);
+	struct simplekms_device *sdev;
+
+	spin_lock(&simplekms_drvdata_lock);
+	sdev = platform_get_drvdata(pdev);
+	platform_set_drvdata(pdev, NULL);
+	spin_unlock(&simplekms_drvdata_lock);
+
+	/*
+	 * The platform driver shares its reference to dev with the
+	 * platform helpers for apertures. That reference is either
+	 * released here when unloading the driver; or it's released
+	 * when the driver gets kicked out by another driver. In the
+	 * latter case, the aperture release routine clears the data
+	 * field of the platform device.
+	 *
+	 * Therefore, sdev being NULL is a valid state if the driver
+	 * has been kicked out by another DRM driver. In this case,
+	 * it's all been cleaned up and we can return immediately.
+	 */
+	if (!sdev)
+		return 0;
 
 	simplekms_device_cleanup(sdev);
 
-- 
2.27.0

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Re: [PATCH 9/9] drm/simplekms: Acquire memory aperture for framebuffer

[Daniel Vetter]

On Thu, Jun 25, 2020 at 02:00:11PM +0200, Thomas Zimmermann wrote:
> We register the simplekms device with the DRM platform helpers. A
> native driver for the graphics hardware will kickout the simplekms
> driver before taking over the device.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/tiny/Kconfig     |  1 +
>  drivers/gpu/drm/tiny/simplekms.c | 94 +++++++++++++++++++++++++++++++-
>  2 files changed, 92 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> index 50dbde8bdcb2..a47ed337a7fe 100644
> --- a/drivers/gpu/drm/tiny/Kconfig
> +++ b/drivers/gpu/drm/tiny/Kconfig
> @@ -33,6 +33,7 @@ config DRM_SIMPLEKMS
>  	depends on DRM
>  	select DRM_GEM_SHMEM_HELPER
>  	select DRM_KMS_HELPER
> +	select DRM_PLATFORM_HELPER
>  	help
>  	  DRM driver for simple platform-provided framebuffers.
>  
> diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
> index ae5d3cbadbe8..a903a4e0100a 100644
> --- a/drivers/gpu/drm/tiny/simplekms.c
> +++ b/drivers/gpu/drm/tiny/simplekms.c
> @@ -5,6 +5,7 @@
>  #include <linux/platform_data/simplefb.h>
>  #include <linux/platform_device.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/spinlock.h>
>  
>  #include <drm/drm_atomic_state_helper.h>
>  #include <drm/drm_connector.h>
> @@ -17,6 +18,7 @@
>  #include <drm/drm_gem_shmem_helper.h>
>  #include <drm/drm_managed.h>
>  #include <drm/drm_modeset_helper_vtables.h>
> +#include <drm/drm_platform.h>
>  #include <drm/drm_probe_helper.h>
>  #include <drm/drm_simple_kms_helper.h>
>  
> @@ -36,6 +38,12 @@
>  #define SIMPLEKMS_MODE(hd, vd)	\
>  	DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
>  
> +/*
> + * Protects the platform device's drvdata against
> + * concurrent manipulation.
> + */
> +static DEFINE_SPINLOCK(simplekms_drvdata_lock);
> +
>  /*
>   * Helpers for simplefb
>   */
> @@ -211,6 +219,7 @@ struct simplekms_device {
>  	unsigned int pitch;
>  
>  	/* memory management */
> +	struct drm_aperture *aperture;
>  	struct resource *mem;
>  	void __iomem *screen_base;
>  
> @@ -224,6 +233,8 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
>  	return container_of(dev, struct simplekms_device, dev);
>  }
>  
> +static void simplekms_device_cleanup(struct simplekms_device *sdev);
> +
>  /*
>   * Hardware
>   */
> @@ -514,22 +525,72 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
>   * Memory management
>   */
>  
> +static void simplekms_aperture_kickout(struct drm_aperture *ap)
> +{
> +	struct drm_device *dev = ap->dev;
> +	struct simplekms_device *sdev = simplekms_device_of_dev(dev);
> +	struct platform_device *pdev = sdev->pdev;
> +
> +	if (WARN_ON(!sdev->aperture))
> +		return; /* BUG: driver already got kicked out */
> +
> +	drm_dev_unregister(dev);

From a semantic pov I think the platform driver getting kicked out is more
like a hotunplug, so drm_dev_unplug(dev); here is imo better.

That then also gives you a nice drm_dev_enter/exit to sprinkle over the
various driver callbacks, instead of the racy ->aperture check reinvented
wheel here.

I also wonder whether we couldn't go full driver model for these platform
devices, and instead of this here call a core driver model function to
force the unbding of the driver. Only change we'd need it that our
->remove hook uses drm_dev_unplug().

Also I guess this nice plan doesn't work if efifb or vesafb don't have a
platform_device of their own that the drm_platform.c code could use to
nuke platform drivers. But if they have, we could just use
device_driver_detach() from drm_platform.c and wouldn't need any of this.
Worst case efi and vesa drm drivers could instantiate the platform device
they bind against themselves ...

I think that would be a lot cleaner than hand-rolling our own hotunplug
infrastructure here.

Adding Greg in case we're missing anything here.

> +
> +	sdev->aperture = NULL; /* memory is released by platform helpers */
> +
> +	spin_lock(&simplekms_drvdata_lock);
> +	sdev = platform_get_drvdata(pdev);
> +	platform_set_drvdata(pdev, NULL); /* required; see simplekms_remove() */
> +	spin_unlock(&simplekms_drvdata_lock);
> +
> +	/*
> +	 * Return if a concurrent simplekms_remove() cleans up the
> +	 * device. See simplekms_remove().
> +	 */
> +	if (!sdev)
> +		return;
> +
> +	/*
> +	 * After the aperture has been released, there's no reason
> +	 * to keep the DRM device around.
> +	 */
> +	simplekms_device_cleanup(sdev);

Uh, you already unregistered, this unregisters again. Maybe a bit too much
:-)

> +}
> +
> +static const struct drm_aperture_funcs simplekms_aperture_funcs = {
> +	.kickout = simplekms_aperture_kickout,
> +};
> +
>  static int simplekms_device_init_mm(struct simplekms_device *sdev)
>  {
> +	struct drm_device *dev = &sdev->dev;
>  	struct platform_device *pdev = sdev->pdev;
>  	struct resource *mem;
> +	struct drm_aperture *ap;
>  	void __iomem *screen_base;
> +	int ret;
>  
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	if (!mem)
>  		return -EINVAL;
>  
> +	ap = drmm_aperture_acquire(dev, mem->start, resource_size(mem),
> +				   &simplekms_aperture_funcs);
> +	if (IS_ERR(ap)) {
> +		ret = PTR_ERR(ap);
> +		drm_err(dev,
> +			"could not acquire memory range [0x%llx:0x%llx]: "
> +			"error %d\n", mem->start, mem->end, ret);
> +		return ret;
> +	}
> +
>  	screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
>  				      resource_size(mem));
>  	if (!screen_base)
>  		return -ENOMEM;
>  
>  	sdev->mem = mem;
> +	sdev->aperture = ap;
>  	sdev->screen_base = screen_base;
>  
>  	return 0;
> @@ -625,6 +686,9 @@ simplekms_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
>  	struct drm_framebuffer *fb = state->fb;
>  	void *vmap;
>  
> +	if (!sdev->aperture)
> +		return;
> +
>  	vmap = drm_gem_shmem_vmap(fb->obj[0]);
>  	if (!vmap)
>  		return;
> @@ -645,6 +709,9 @@ simplekms_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
>  	struct drm_rect clip;
>  	void *vmap;
>  
> +	if (!sdev->aperture)
> +		return;
> +
>  	if (!drm_atomic_helper_damage_merged(old_plane_state, state, &clip))
>  		return;
>  
> @@ -716,11 +783,12 @@ static int simplekms_device_init_modeset(struct simplekms_device *sdev)
>   * Init / Cleanup
>   */
>  
> -static void simplekms_device_cleanup(struct simplekms_device* sdev)
> +static void simplekms_device_cleanup(struct simplekms_device *sdev)
>  {
>  	struct drm_device *dev = &sdev->dev;
>  
> -	drm_dev_unregister(dev);
> +	if (dev->registered)
> +		drm_dev_unregister(dev);
>  }
>  
>  static struct simplekms_device *
> @@ -797,7 +865,27 @@ static int simplekms_probe(struct platform_device *pdev)
>  
>  static int simplekms_remove(struct platform_device *pdev)
>  {
> -	struct simplekms_device *sdev = platform_get_drvdata(pdev);
> +	struct simplekms_device *sdev;
> +
> +	spin_lock(&simplekms_drvdata_lock);
> +	sdev = platform_get_drvdata(pdev);
> +	platform_set_drvdata(pdev, NULL);
> +	spin_unlock(&simplekms_drvdata_lock);
> +
> +	/*
> +	 * The platform driver shares its reference to dev with the
> +	 * platform helpers for apertures. That reference is either
> +	 * released here when unloading the driver; or it's released
> +	 * when the driver gets kicked out by another driver. In the
> +	 * latter case, the aperture release routine clears the data
> +	 * field of the platform device.
> +	 *
> +	 * Therefore, sdev being NULL is a valid state if the driver
> +	 * has been kicked out by another DRM driver. In this case,
> +	 * it's all been cleaned up and we can return immediately.
> +	 */
> +	if (!sdev)
> +		return 0;
>  
>  	simplekms_device_cleanup(sdev);
>  
> -- 
> 2.27.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH 9/9] drm/simplekms: Acquire memory aperture for framebuffer

[Greg KH]

On Mon, Jun 29, 2020 at 11:22:30AM +0200, Daniel Vetter wrote:
> On Thu, Jun 25, 2020 at 02:00:11PM +0200, Thomas Zimmermann wrote:
> > We register the simplekms device with the DRM platform helpers. A
> > native driver for the graphics hardware will kickout the simplekms
> > driver before taking over the device.
> > 
> > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> > ---
> >  drivers/gpu/drm/tiny/Kconfig     |  1 +
> >  drivers/gpu/drm/tiny/simplekms.c | 94 +++++++++++++++++++++++++++++++-
> >  2 files changed, 92 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> > index 50dbde8bdcb2..a47ed337a7fe 100644
> > --- a/drivers/gpu/drm/tiny/Kconfig
> > +++ b/drivers/gpu/drm/tiny/Kconfig
> > @@ -33,6 +33,7 @@ config DRM_SIMPLEKMS
> >  	depends on DRM
> >  	select DRM_GEM_SHMEM_HELPER
> >  	select DRM_KMS_HELPER
> > +	select DRM_PLATFORM_HELPER
> >  	help
> >  	  DRM driver for simple platform-provided framebuffers.
> >  
> > diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
> > index ae5d3cbadbe8..a903a4e0100a 100644
> > --- a/drivers/gpu/drm/tiny/simplekms.c
> > +++ b/drivers/gpu/drm/tiny/simplekms.c
> > @@ -5,6 +5,7 @@
> >  #include <linux/platform_data/simplefb.h>
> >  #include <linux/platform_device.h>
> >  #include <linux/regulator/consumer.h>
> > +#include <linux/spinlock.h>
> >  
> >  #include <drm/drm_atomic_state_helper.h>
> >  #include <drm/drm_connector.h>
> > @@ -17,6 +18,7 @@
> >  #include <drm/drm_gem_shmem_helper.h>
> >  #include <drm/drm_managed.h>
> >  #include <drm/drm_modeset_helper_vtables.h>
> > +#include <drm/drm_platform.h>
> >  #include <drm/drm_probe_helper.h>
> >  #include <drm/drm_simple_kms_helper.h>
> >  
> > @@ -36,6 +38,12 @@
> >  #define SIMPLEKMS_MODE(hd, vd)	\
> >  	DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
> >  
> > +/*
> > + * Protects the platform device's drvdata against
> > + * concurrent manipulation.
> > + */
> > +static DEFINE_SPINLOCK(simplekms_drvdata_lock);
> > +
> >  /*
> >   * Helpers for simplefb
> >   */
> > @@ -211,6 +219,7 @@ struct simplekms_device {
> >  	unsigned int pitch;
> >  
> >  	/* memory management */
> > +	struct drm_aperture *aperture;
> >  	struct resource *mem;
> >  	void __iomem *screen_base;
> >  
> > @@ -224,6 +233,8 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
> >  	return container_of(dev, struct simplekms_device, dev);
> >  }
> >  
> > +static void simplekms_device_cleanup(struct simplekms_device *sdev);
> > +
> >  /*
> >   * Hardware
> >   */
> > @@ -514,22 +525,72 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
> >   * Memory management
> >   */
> >  
> > +static void simplekms_aperture_kickout(struct drm_aperture *ap)
> > +{
> > +	struct drm_device *dev = ap->dev;
> > +	struct simplekms_device *sdev = simplekms_device_of_dev(dev);
> > +	struct platform_device *pdev = sdev->pdev;
> > +
> > +	if (WARN_ON(!sdev->aperture))
> > +		return; /* BUG: driver already got kicked out */
> > +
> > +	drm_dev_unregister(dev);
> 
> >From a semantic pov I think the platform driver getting kicked out is more
> like a hotunplug, so drm_dev_unplug(dev); here is imo better.
> 
> That then also gives you a nice drm_dev_enter/exit to sprinkle over the
> various driver callbacks, instead of the racy ->aperture check reinvented
> wheel here.
> 
> I also wonder whether we couldn't go full driver model for these platform
> devices, and instead of this here call a core driver model function to
> force the unbding of the driver. Only change we'd need it that our
> ->remove hook uses drm_dev_unplug().

Yes, please do that.  Or, use the "virtual bus/device" code that some
people at Intel are still trying to get into mergable shape.  See the
posts on the netdev list for those details.

Don't use platform devices for anything that is not actually a platform
device (i.e. something described by hardware resources).

thanks,

greg k-h
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Re: [PATCH 9/9] drm/simplekms: Acquire memory aperture for framebuffer

[Mark Brown]

[-- Attachment #1.1: Type: text/plain, Size: 356 bytes --]

On Mon, Jun 29, 2020 at 06:04:21PM +0200, Greg KH wrote:

> Yes, please do that.  Or, use the "virtual bus/device" code that some
> people at Intel are still trying to get into mergable shape.  See the
> posts on the netdev list for those details.

Any pointers on that?  There's also some ongoing discussion with MFD and
that's not been mentioned at all.

[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

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Re: [PATCH 9/9] drm/simplekms: Acquire memory aperture for framebuffer

[Greg KH]

On Mon, Jun 29, 2020 at 05:23:16PM +0100, Mark Brown wrote:
> On Mon, Jun 29, 2020 at 06:04:21PM +0200, Greg KH wrote:
> 
> > Yes, please do that.  Or, use the "virtual bus/device" code that some
> > people at Intel are still trying to get into mergable shape.  See the
> > posts on the netdev list for those details.
> 
> Any pointers on that?  There's also some ongoing discussion with MFD and
> that's not been mentioned at all.

https://lore.kernel.org/r/20200520070227.3392100-2-jeffrey.t.kirsher@intel.com
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Re: [PATCH 9/9] drm/simplekms: Acquire memory aperture for framebuffer

[Rob Herring]

On Mon, Jun 29, 2020 at 10:04 AM Greg KH <gregkh@linuxfoundation.org> wrote:
>
> On Mon, Jun 29, 2020 at 11:22:30AM +0200, Daniel Vetter wrote:
> > On Thu, Jun 25, 2020 at 02:00:11PM +0200, Thomas Zimmermann wrote:
> > > We register the simplekms device with the DRM platform helpers. A
> > > native driver for the graphics hardware will kickout the simplekms
> > > driver before taking over the device.
> > >
> > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> > > ---
> > >  drivers/gpu/drm/tiny/Kconfig     |  1 +
> > >  drivers/gpu/drm/tiny/simplekms.c | 94 +++++++++++++++++++++++++++++++-
> > >  2 files changed, 92 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> > > index 50dbde8bdcb2..a47ed337a7fe 100644
> > > --- a/drivers/gpu/drm/tiny/Kconfig
> > > +++ b/drivers/gpu/drm/tiny/Kconfig
> > > @@ -33,6 +33,7 @@ config DRM_SIMPLEKMS
> > >     depends on DRM
> > >     select DRM_GEM_SHMEM_HELPER
> > >     select DRM_KMS_HELPER
> > > +   select DRM_PLATFORM_HELPER
> > >     help
> > >       DRM driver for simple platform-provided framebuffers.
> > >
> > > diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
> > > index ae5d3cbadbe8..a903a4e0100a 100644
> > > --- a/drivers/gpu/drm/tiny/simplekms.c
> > > +++ b/drivers/gpu/drm/tiny/simplekms.c
> > > @@ -5,6 +5,7 @@
> > >  #include <linux/platform_data/simplefb.h>
> > >  #include <linux/platform_device.h>
> > >  #include <linux/regulator/consumer.h>
> > > +#include <linux/spinlock.h>
> > >
> > >  #include <drm/drm_atomic_state_helper.h>
> > >  #include <drm/drm_connector.h>
> > > @@ -17,6 +18,7 @@
> > >  #include <drm/drm_gem_shmem_helper.h>
> > >  #include <drm/drm_managed.h>
> > >  #include <drm/drm_modeset_helper_vtables.h>
> > > +#include <drm/drm_platform.h>
> > >  #include <drm/drm_probe_helper.h>
> > >  #include <drm/drm_simple_kms_helper.h>
> > >
> > > @@ -36,6 +38,12 @@
> > >  #define SIMPLEKMS_MODE(hd, vd)     \
> > >     DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
> > >
> > > +/*
> > > + * Protects the platform device's drvdata against
> > > + * concurrent manipulation.
> > > + */
> > > +static DEFINE_SPINLOCK(simplekms_drvdata_lock);
> > > +
> > >  /*
> > >   * Helpers for simplefb
> > >   */
> > > @@ -211,6 +219,7 @@ struct simplekms_device {
> > >     unsigned int pitch;
> > >
> > >     /* memory management */
> > > +   struct drm_aperture *aperture;
> > >     struct resource *mem;
> > >     void __iomem *screen_base;
> > >
> > > @@ -224,6 +233,8 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
> > >     return container_of(dev, struct simplekms_device, dev);
> > >  }
> > >
> > > +static void simplekms_device_cleanup(struct simplekms_device *sdev);
> > > +
> > >  /*
> > >   * Hardware
> > >   */
> > > @@ -514,22 +525,72 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
> > >   * Memory management
> > >   */
> > >
> > > +static void simplekms_aperture_kickout(struct drm_aperture *ap)
> > > +{
> > > +   struct drm_device *dev = ap->dev;
> > > +   struct simplekms_device *sdev = simplekms_device_of_dev(dev);
> > > +   struct platform_device *pdev = sdev->pdev;
> > > +
> > > +   if (WARN_ON(!sdev->aperture))
> > > +           return; /* BUG: driver already got kicked out */
> > > +
> > > +   drm_dev_unregister(dev);
> >
> > >From a semantic pov I think the platform driver getting kicked out is more
> > like a hotunplug, so drm_dev_unplug(dev); here is imo better.
> >
> > That then also gives you a nice drm_dev_enter/exit to sprinkle over the
> > various driver callbacks, instead of the racy ->aperture check reinvented
> > wheel here.
> >
> > I also wonder whether we couldn't go full driver model for these platform
> > devices, and instead of this here call a core driver model function to
> > force the unbding of the driver. Only change we'd need it that our
> > ->remove hook uses drm_dev_unplug().
>
> Yes, please do that.  Or, use the "virtual bus/device" code that some
> people at Intel are still trying to get into mergable shape.  See the
> posts on the netdev list for those details.
>
> Don't use platform devices for anything that is not actually a platform
> device (i.e. something described by hardware resources).

Well, 'simple-framebuffer' is described by DT and includes h/w
resources such as clocks. So this is a gray area. I'm not saying we
couldn't use virtual bus for DT nodes, but we'll need some clear
guidelines of when to use virtual vs. platform devices. No doubt I'll
get a 'virtual bus' binding if folks are directed to make things a
virtual device.

Rob
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Re: [PATCH 9/9] drm/simplekms: Acquire memory aperture for framebuffer

[Greg KH]

On Mon, Jun 29, 2020 at 08:13:51PM -0600, Rob Herring wrote:
> On Mon, Jun 29, 2020 at 10:04 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Mon, Jun 29, 2020 at 11:22:30AM +0200, Daniel Vetter wrote:
> > > On Thu, Jun 25, 2020 at 02:00:11PM +0200, Thomas Zimmermann wrote:
> > > > We register the simplekms device with the DRM platform helpers. A
> > > > native driver for the graphics hardware will kickout the simplekms
> > > > driver before taking over the device.
> > > >
> > > > Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> > > > ---
> > > >  drivers/gpu/drm/tiny/Kconfig     |  1 +
> > > >  drivers/gpu/drm/tiny/simplekms.c | 94 +++++++++++++++++++++++++++++++-
> > > >  2 files changed, 92 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
> > > > index 50dbde8bdcb2..a47ed337a7fe 100644
> > > > --- a/drivers/gpu/drm/tiny/Kconfig
> > > > +++ b/drivers/gpu/drm/tiny/Kconfig
> > > > @@ -33,6 +33,7 @@ config DRM_SIMPLEKMS
> > > >     depends on DRM
> > > >     select DRM_GEM_SHMEM_HELPER
> > > >     select DRM_KMS_HELPER
> > > > +   select DRM_PLATFORM_HELPER
> > > >     help
> > > >       DRM driver for simple platform-provided framebuffers.
> > > >
> > > > diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
> > > > index ae5d3cbadbe8..a903a4e0100a 100644
> > > > --- a/drivers/gpu/drm/tiny/simplekms.c
> > > > +++ b/drivers/gpu/drm/tiny/simplekms.c
> > > > @@ -5,6 +5,7 @@
> > > >  #include <linux/platform_data/simplefb.h>
> > > >  #include <linux/platform_device.h>
> > > >  #include <linux/regulator/consumer.h>
> > > > +#include <linux/spinlock.h>
> > > >
> > > >  #include <drm/drm_atomic_state_helper.h>
> > > >  #include <drm/drm_connector.h>
> > > > @@ -17,6 +18,7 @@
> > > >  #include <drm/drm_gem_shmem_helper.h>
> > > >  #include <drm/drm_managed.h>
> > > >  #include <drm/drm_modeset_helper_vtables.h>
> > > > +#include <drm/drm_platform.h>
> > > >  #include <drm/drm_probe_helper.h>
> > > >  #include <drm/drm_simple_kms_helper.h>
> > > >
> > > > @@ -36,6 +38,12 @@
> > > >  #define SIMPLEKMS_MODE(hd, vd)     \
> > > >     DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
> > > >
> > > > +/*
> > > > + * Protects the platform device's drvdata against
> > > > + * concurrent manipulation.
> > > > + */
> > > > +static DEFINE_SPINLOCK(simplekms_drvdata_lock);
> > > > +
> > > >  /*
> > > >   * Helpers for simplefb
> > > >   */
> > > > @@ -211,6 +219,7 @@ struct simplekms_device {
> > > >     unsigned int pitch;
> > > >
> > > >     /* memory management */
> > > > +   struct drm_aperture *aperture;
> > > >     struct resource *mem;
> > > >     void __iomem *screen_base;
> > > >
> > > > @@ -224,6 +233,8 @@ static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
> > > >     return container_of(dev, struct simplekms_device, dev);
> > > >  }
> > > >
> > > > +static void simplekms_device_cleanup(struct simplekms_device *sdev);
> > > > +
> > > >  /*
> > > >   * Hardware
> > > >   */
> > > > @@ -514,22 +525,72 @@ static int simplekms_device_init_fb(struct simplekms_device *sdev)
> > > >   * Memory management
> > > >   */
> > > >
> > > > +static void simplekms_aperture_kickout(struct drm_aperture *ap)
> > > > +{
> > > > +   struct drm_device *dev = ap->dev;
> > > > +   struct simplekms_device *sdev = simplekms_device_of_dev(dev);
> > > > +   struct platform_device *pdev = sdev->pdev;
> > > > +
> > > > +   if (WARN_ON(!sdev->aperture))
> > > > +           return; /* BUG: driver already got kicked out */
> > > > +
> > > > +   drm_dev_unregister(dev);
> > >
> > > >From a semantic pov I think the platform driver getting kicked out is more
> > > like a hotunplug, so drm_dev_unplug(dev); here is imo better.
> > >
> > > That then also gives you a nice drm_dev_enter/exit to sprinkle over the
> > > various driver callbacks, instead of the racy ->aperture check reinvented
> > > wheel here.
> > >
> > > I also wonder whether we couldn't go full driver model for these platform
> > > devices, and instead of this here call a core driver model function to
> > > force the unbding of the driver. Only change we'd need it that our
> > > ->remove hook uses drm_dev_unplug().
> >
> > Yes, please do that.  Or, use the "virtual bus/device" code that some
> > people at Intel are still trying to get into mergable shape.  See the
> > posts on the netdev list for those details.
> >
> > Don't use platform devices for anything that is not actually a platform
> > device (i.e. something described by hardware resources).
> 
> Well, 'simple-framebuffer' is described by DT and includes h/w
> resources such as clocks. So this is a gray area. I'm not saying we
> couldn't use virtual bus for DT nodes, but we'll need some clear
> guidelines of when to use virtual vs. platform devices. No doubt I'll
> get a 'virtual bus' binding if folks are directed to make things a
> virtual device.

If it is described by DT, then I have no objection for it to be a
platform device.

thanks,

greg k-h
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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Hans de Goede]

Hi,

On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
> This patchset adds support for simple-framebuffer platform devices and
> a handover mechanism for native drivers to take-over control of the
> hardware.
> 
> The new driver, called simplekms, binds to a simple-frambuffer platform
> device. The kernel's boot code creates such devices for firmware-provided
> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
> loader sets up the framebuffers. Description via device tree is also an
> option.
> 
> Simplekms is small enough to be linked into the kernel. The driver's main
> purpose is to provide graphical output during the early phases of the boot
> process, before the native DRM drivers are available. Native drivers are
> typically loaded from an initrd ram disk. Occationally simplekms can also
> serve as interim solution on graphics hardware without native DRM driver.

Cool, thank you for doing this, this is a very welcome change,
but ... (see below).

> So far distributions rely on fbdev drivers, such as efifb, vesafb or
> simplefb, for early-boot graphical output. However fbdev is deprecated and
> the drivers do not provide DRM interfaces for modern userspace.
> 
> Patches 1 and 2 prepare the DRM format helpers for simplekms.
> 
> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
> regulators. It's based on the simplefb drivers, but has been modified for
> DRM.
> 
> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
> framebuffer's I/O-memory range and provides a callback function to be
> removed by a native driver. The native driver will remove simplekms before
> taking over the hardware. The removal is integrated into existing helpers,
> so drivers use it automatically.
> 
> I tested simplekms with x86 EFI and VESA framebuffers, which both work
> reliably. The fbdev console and Weston work automatically. Xorg requires
> manual configuration of the device. Xorgs current modesetting driver does
> not work with both, platform and PCI device, for the same physical
> hardware. Once configured, X11 works.

Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
around and break userspace. OTOH this does seem like an userspace issue
and not something which we can (or should try to) fix in the kernel.

I guess the solution will have to be to have this default to N for now
in Kconfig and clearly mention in the Kconfig help text that this needs
a fixed Xorg modesetting driver before it can be enabled.

Any chance you have time to work on fixing the Xorg modesetting driver
so that this will just work with the standard Xorg autoconfiguration
stuff?

> One cosmetical issue is that simplekms's device file is card0 and the
> native driver's device file is card1. After simplekms has been kicked out,
> only card1 is left. This does not seem to be a practical problem however.
> 
> TODO/IDEAS:
> 
> 	* provide deferred takeover

I assume you mean akin to CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER ?
I don't think you need to do anything for that, as long as you just
leave the fb contents intact until requested to change it.

Right now with flickerfree boot we have fbcon on top of efifb and
efifb does not do anything special wrt
CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
ATM it does draw/restore the ACPI BGRT logo since since some firmwares
don't draw that themselves, but that is not necessary in most cases
and other then that all the deferred takeover magic is in the fbcon
code, it does not bind to the fbdev (and thus does not draw to it)
until the first time the kernel tries to output text to the console,
together with the "quiet" kernel commandline argument that ensures
that the fb is kept unmodified until e.g. a panic happens.

With simplekms we would replace "fbcon on top of efifb" with
"fbcon on top of emulated-fbdev on top of simplekms" so as long
as the emulated-fbdev and simplekms code defer from say clearing
the screen to black, but keep it as is. Then the fb contents
should be preserved until fbcon decides to takeover the fbdev
and draw to it.

> 	* provide bootsplash DRM client

Hmm, I guess this might be interesting for simple cases, but
although I would love to kill plymouth (I've become one of the
upstream maintainers for it) I'm afraid it is not that easy,
it does a bunch of stuff which will be tricky to do in the kernel:

1) Ask the user for diskcrypt passwords:
https://ic.pics.livejournal.com/hansdegoede/13347631/1496/1496_900.png

2) Show a nice splash + progressbar when installing updates in
offline updates mode:
https://ic.pics.livejournal.com/hansdegoede/13347631/899/899_900.png

Still this would be nice for the non diskcrypt case I guess, then
we could not use plymouth during normal boot and only use it
for offline updates and it would also be nice for various embedded
cases.

Regards,

Hans





> 	* make simplekms usable with ARM-EFI fbs
> 
> Thomas Zimmermann (9):
>    drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()
>    drm/format-helper: Add blitter functions
>    drm: Add simplekms driver
>    drm/simplekms: Add fbdev emulation
>    drm/simplekms: Initialize framebuffer data from device-tree node
>    drm/simplekms: Acquire clocks from DT device node
>    drm/simplekms: Acquire regulators from DT device node
>    drm: Add infrastructure for platform devices
>    drm/simplekms: Acquire memory aperture for framebuffer
> 
>   MAINTAINERS                            |   6 +
>   drivers/gpu/drm/Kconfig                |   6 +
>   drivers/gpu/drm/Makefile               |   1 +
>   drivers/gpu/drm/drm_format_helper.c    |  96 ++-
>   drivers/gpu/drm/drm_platform.c         | 118 ++++
>   drivers/gpu/drm/mgag200/mgag200_mode.c |   2 +-
>   drivers/gpu/drm/tiny/Kconfig           |  17 +
>   drivers/gpu/drm/tiny/Makefile          |   1 +
>   drivers/gpu/drm/tiny/cirrus.c          |   2 +-
>   drivers/gpu/drm/tiny/simplekms.c       | 906 +++++++++++++++++++++++++
>   include/drm/drm_fb_helper.h            |  18 +-
>   include/drm/drm_format_helper.h        |  10 +-
>   include/drm/drm_platform.h             |  42 ++
>   13 files changed, 1217 insertions(+), 8 deletions(-)
>   create mode 100644 drivers/gpu/drm/drm_platform.c
>   create mode 100644 drivers/gpu/drm/tiny/simplekms.c
>   create mode 100644 include/drm/drm_platform.h
> 
> --
> 2.27.0
> 

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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Daniel Vetter]

On Mon, Jun 29, 2020 at 11:39 AM Hans de Goede <hdegoede@redhat.com> wrote:
>
> Hi,
>
> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
> > This patchset adds support for simple-framebuffer platform devices and
> > a handover mechanism for native drivers to take-over control of the
> > hardware.
> >
> > The new driver, called simplekms, binds to a simple-frambuffer platform
> > device. The kernel's boot code creates such devices for firmware-provided
> > framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
> > loader sets up the framebuffers. Description via device tree is also an
> > option.
> >
> > Simplekms is small enough to be linked into the kernel. The driver's main
> > purpose is to provide graphical output during the early phases of the boot
> > process, before the native DRM drivers are available. Native drivers are
> > typically loaded from an initrd ram disk. Occationally simplekms can also
> > serve as interim solution on graphics hardware without native DRM driver.
>
> Cool, thank you for doing this, this is a very welcome change,
> but ... (see below).
>
> > So far distributions rely on fbdev drivers, such as efifb, vesafb or
> > simplefb, for early-boot graphical output. However fbdev is deprecated and
> > the drivers do not provide DRM interfaces for modern userspace.
> >
> > Patches 1 and 2 prepare the DRM format helpers for simplekms.
> >
> > Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
> > and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
> > pageflips, SHMEM buffers are copied into the framebuffer memory, similar
> > to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
> > regulators. It's based on the simplefb drivers, but has been modified for
> > DRM.
> >
> > Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
> > framebuffer's I/O-memory range and provides a callback function to be
> > removed by a native driver. The native driver will remove simplekms before
> > taking over the hardware. The removal is integrated into existing helpers,
> > so drivers use it automatically.
> >
> > I tested simplekms with x86 EFI and VESA framebuffers, which both work
> > reliably. The fbdev console and Weston work automatically. Xorg requires
> > manual configuration of the device. Xorgs current modesetting driver does
> > not work with both, platform and PCI device, for the same physical
> > hardware. Once configured, X11 works.
>
> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
> around and break userspace. OTOH this does seem like an userspace issue
> and not something which we can (or should try to) fix in the kernel.
>
> I guess the solution will have to be to have this default to N for now
> in Kconfig and clearly mention in the Kconfig help text that this needs
> a fixed Xorg modesetting driver before it can be enabled.
>
> Any chance you have time to work on fixing the Xorg modesetting driver
> so that this will just work with the standard Xorg autoconfiguration
> stuff?

Hm, why do we even have both platform and pci drivers visible at the
same time? I thought the point of this is that simplekms is built-in,
then initrd loads the real drm driver, and by the time Xorg is
running, simplekms should be long gone.

Maybe a few more details of what's going wrong and why to help unconfuse me?

> > One cosmetical issue is that simplekms's device file is card0 and the
> > native driver's device file is card1. After simplekms has been kicked out,
> > only card1 is left. This does not seem to be a practical problem however.
> >
> > TODO/IDEAS:
> >
> >       * provide deferred takeover
>
> I assume you mean akin to CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER ?
> I don't think you need to do anything for that, as long as you just
> leave the fb contents intact until requested to change it.

Yeah I think fastboot support is a requirement here, otherwise all the
deferred fb takeover should already happen automatically I think.

Also fastboot = flickerfree, depending whether you care more about
"fewer modesets to save time" or "less flickering because it's ugly"
:-)

Cheers, Daniel

> Right now with flickerfree boot we have fbcon on top of efifb and
> efifb does not do anything special wrt
> CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
> ATM it does draw/restore the ACPI BGRT logo since since some firmwares
> don't draw that themselves, but that is not necessary in most cases
> and other then that all the deferred takeover magic is in the fbcon
> code, it does not bind to the fbdev (and thus does not draw to it)
> until the first time the kernel tries to output text to the console,
> together with the "quiet" kernel commandline argument that ensures
> that the fb is kept unmodified until e.g. a panic happens.
>
> With simplekms we would replace "fbcon on top of efifb" with
> "fbcon on top of emulated-fbdev on top of simplekms" so as long
> as the emulated-fbdev and simplekms code defer from say clearing
> the screen to black, but keep it as is. Then the fb contents
> should be preserved until fbcon decides to takeover the fbdev
> and draw to it.
>
> >       * provide bootsplash DRM client
>
> Hmm, I guess this might be interesting for simple cases, but
> although I would love to kill plymouth (I've become one of the
> upstream maintainers for it) I'm afraid it is not that easy,
> it does a bunch of stuff which will be tricky to do in the kernel:
>
> 1) Ask the user for diskcrypt passwords:
> https://ic.pics.livejournal.com/hansdegoede/13347631/1496/1496_900.png
>
> 2) Show a nice splash + progressbar when installing updates in
> offline updates mode:
> https://ic.pics.livejournal.com/hansdegoede/13347631/899/899_900.png
>
> Still this would be nice for the non diskcrypt case I guess, then
> we could not use plymouth during normal boot and only use it
> for offline updates and it would also be nice for various embedded
> cases.
>
> Regards,
>
> Hans
>
>
>
>
>
> >       * make simplekms usable with ARM-EFI fbs
> >
> > Thomas Zimmermann (9):
> >    drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()
> >    drm/format-helper: Add blitter functions
> >    drm: Add simplekms driver
> >    drm/simplekms: Add fbdev emulation
> >    drm/simplekms: Initialize framebuffer data from device-tree node
> >    drm/simplekms: Acquire clocks from DT device node
> >    drm/simplekms: Acquire regulators from DT device node
> >    drm: Add infrastructure for platform devices
> >    drm/simplekms: Acquire memory aperture for framebuffer
> >
> >   MAINTAINERS                            |   6 +
> >   drivers/gpu/drm/Kconfig                |   6 +
> >   drivers/gpu/drm/Makefile               |   1 +
> >   drivers/gpu/drm/drm_format_helper.c    |  96 ++-
> >   drivers/gpu/drm/drm_platform.c         | 118 ++++
> >   drivers/gpu/drm/mgag200/mgag200_mode.c |   2 +-
> >   drivers/gpu/drm/tiny/Kconfig           |  17 +
> >   drivers/gpu/drm/tiny/Makefile          |   1 +
> >   drivers/gpu/drm/tiny/cirrus.c          |   2 +-
> >   drivers/gpu/drm/tiny/simplekms.c       | 906 +++++++++++++++++++++++++
> >   include/drm/drm_fb_helper.h            |  18 +-
> >   include/drm/drm_format_helper.h        |  10 +-
> >   include/drm/drm_platform.h             |  42 ++
> >   13 files changed, 1217 insertions(+), 8 deletions(-)
> >   create mode 100644 drivers/gpu/drm/drm_platform.c
> >   create mode 100644 drivers/gpu/drm/tiny/simplekms.c
> >   create mode 100644 include/drm/drm_platform.h
> >
> > --
> > 2.27.0
> >
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Hans de Goede]

Hi,

On 6/30/20 11:06 AM, Daniel Vetter wrote:
> On Mon, Jun 29, 2020 at 11:39 AM Hans de Goede <hdegoede@redhat.com> wrote:
>>
>> Hi,
>>
>> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
>>> This patchset adds support for simple-framebuffer platform devices and
>>> a handover mechanism for native drivers to take-over control of the
>>> hardware.
>>>
>>> The new driver, called simplekms, binds to a simple-frambuffer platform
>>> device. The kernel's boot code creates such devices for firmware-provided
>>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
>>> loader sets up the framebuffers. Description via device tree is also an
>>> option.
>>>
>>> Simplekms is small enough to be linked into the kernel. The driver's main
>>> purpose is to provide graphical output during the early phases of the boot
>>> process, before the native DRM drivers are available. Native drivers are
>>> typically loaded from an initrd ram disk. Occationally simplekms can also
>>> serve as interim solution on graphics hardware without native DRM driver.
>>
>> Cool, thank you for doing this, this is a very welcome change,
>> but ... (see below).
>>
>>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
>>> simplefb, for early-boot graphical output. However fbdev is deprecated and
>>> the drivers do not provide DRM interfaces for modern userspace.
>>>
>>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
>>>
>>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
>>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
>>> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
>>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
>>> regulators. It's based on the simplefb drivers, but has been modified for
>>> DRM.
>>>
>>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
>>> framebuffer's I/O-memory range and provides a callback function to be
>>> removed by a native driver. The native driver will remove simplekms before
>>> taking over the hardware. The removal is integrated into existing helpers,
>>> so drivers use it automatically.
>>>
>>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
>>> reliably. The fbdev console and Weston work automatically. Xorg requires
>>> manual configuration of the device. Xorgs current modesetting driver does
>>> not work with both, platform and PCI device, for the same physical
>>> hardware. Once configured, X11 works.
>>
>> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
>> around and break userspace. OTOH this does seem like an userspace issue
>> and not something which we can (or should try to) fix in the kernel.
>>
>> I guess the solution will have to be to have this default to N for now
>> in Kconfig and clearly mention in the Kconfig help text that this needs
>> a fixed Xorg modesetting driver before it can be enabled.
>>
>> Any chance you have time to work on fixing the Xorg modesetting driver
>> so that this will just work with the standard Xorg autoconfiguration
>> stuff?
> 
> Hm, why do we even have both platform and pci drivers visible at the
> same time? I thought the point of this is that simplekms is built-in,
> then initrd loads the real drm driver, and by the time Xorg is
> running, simplekms should be long gone.
> 
> Maybe a few more details of what's going wrong and why to help unconfuse me?

I guess that Thomas deliberately disabled the normal kms driver to test this.

Still we should make sure that this (Xorg on simpledrm) works, a user might
see this because of running an older kernel with a newer GPU, or when
using the nvidia binary and thus having nouveau disabled and then installing
a newer kernel which breaks the dkms nvidia module building because of API
changes.

Regards,

Hans

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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 9687 bytes --]

Hi Daniel,

thanks for reviewing most of the patchset.

Am 30.06.20 um 11:06 schrieb Daniel Vetter:
> On Mon, Jun 29, 2020 at 11:39 AM Hans de Goede <hdegoede@redhat.com> wrote:
>>
>> Hi,
>>
>> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
>>> This patchset adds support for simple-framebuffer platform devices and
>>> a handover mechanism for native drivers to take-over control of the
>>> hardware.
>>>
>>> The new driver, called simplekms, binds to a simple-frambuffer platform
>>> device. The kernel's boot code creates such devices for firmware-provided
>>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
>>> loader sets up the framebuffers. Description via device tree is also an
>>> option.
>>>
>>> Simplekms is small enough to be linked into the kernel. The driver's main
>>> purpose is to provide graphical output during the early phases of the boot
>>> process, before the native DRM drivers are available. Native drivers are
>>> typically loaded from an initrd ram disk. Occationally simplekms can also
>>> serve as interim solution on graphics hardware without native DRM driver.
>>
>> Cool, thank you for doing this, this is a very welcome change,
>> but ... (see below).
>>
>>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
>>> simplefb, for early-boot graphical output. However fbdev is deprecated and
>>> the drivers do not provide DRM interfaces for modern userspace.
>>>
>>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
>>>
>>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
>>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
>>> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
>>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
>>> regulators. It's based on the simplefb drivers, but has been modified for
>>> DRM.
>>>
>>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
>>> framebuffer's I/O-memory range and provides a callback function to be
>>> removed by a native driver. The native driver will remove simplekms before
>>> taking over the hardware. The removal is integrated into existing helpers,
>>> so drivers use it automatically.
>>>
>>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
>>> reliably. The fbdev console and Weston work automatically. Xorg requires
>>> manual configuration of the device. Xorgs current modesetting driver does
>>> not work with both, platform and PCI device, for the same physical
>>> hardware. Once configured, X11 works.
>>
>> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
>> around and break userspace. OTOH this does seem like an userspace issue
>> and not something which we can (or should try to) fix in the kernel.
>>
>> I guess the solution will have to be to have this default to N for now
>> in Kconfig and clearly mention in the Kconfig help text that this needs
>> a fixed Xorg modesetting driver before it can be enabled.
>>
>> Any chance you have time to work on fixing the Xorg modesetting driver
>> so that this will just work with the standard Xorg autoconfiguration
>> stuff?
> 
> Hm, why do we even have both platform and pci drivers visible at the
> same time? I thought the point of this is that simplekms is built-in,
> then initrd loads the real drm driver, and by the time Xorg is
> running, simplekms should be long gone.
> 
> Maybe a few more details of what's going wrong and why to help unconfuse me?

I tested simplekms with PCI graphics cards.

Xorg does it's own scanning of the busses. It supports a platform bus,
where it finds the simple-framebuffer device that is driven by
simplekms. Xorg also scans the PCI bus, where is finds the native PCI
device; usually driven by the native driver. It's the same hardware, but
on different busses.

For each device, Xorg tries to configure a screen, the Xorg modeset
driver tried to open the DRM device file and acquire DRM master status
on it. This works for the first screen, but DRM master status can only
be acquired once, so it fails for the second screen. Xorg then aborts
and asks for manual configuration of the display device.

This can be solved by setting the platform device's bus id in the
xorg.conf device section. It just doesn't happen automatically.

I found it hard to find a solution to this. Weston just opens a DRM
device file and uses whatever it gets. Ideally, Xorg would do the same.
That whole bus-scanning exercise gives it a wrong idea on which graphics
devices are available.

One idea for a fix is to compare the device I/O-memory ranges and filter
out duplicates on the Xorg modeset driver. I don't know how reliable
this works in practice or if their are false positives.

A more fundamental solution is to introduce a DRM bus in Xorg that
enumerates all available DRM device files. If there are any, no other
busses would be scanned.

I'm still looking for something better. Idea are highly welcome.

Best regards
Thomas


> 
>>> One cosmetical issue is that simplekms's device file is card0 and the
>>> native driver's device file is card1. After simplekms has been kicked out,
>>> only card1 is left. This does not seem to be a practical problem however.
>>>
>>> TODO/IDEAS:
>>>
>>>       * provide deferred takeover
>>
>> I assume you mean akin to CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER ?
>> I don't think you need to do anything for that, as long as you just
>> leave the fb contents intact until requested to change it.
> 
> Yeah I think fastboot support is a requirement here, otherwise all the
> deferred fb takeover should already happen automatically I think.
> 
> Also fastboot = flickerfree, depending whether you care more about
> "fewer modesets to save time" or "less flickering because it's ugly"
> :-)
> 
> Cheers, Daniel
> 
>> Right now with flickerfree boot we have fbcon on top of efifb and
>> efifb does not do anything special wrt
>> CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
>> ATM it does draw/restore the ACPI BGRT logo since since some firmwares
>> don't draw that themselves, but that is not necessary in most cases
>> and other then that all the deferred takeover magic is in the fbcon
>> code, it does not bind to the fbdev (and thus does not draw to it)
>> until the first time the kernel tries to output text to the console,
>> together with the "quiet" kernel commandline argument that ensures
>> that the fb is kept unmodified until e.g. a panic happens.
>>
>> With simplekms we would replace "fbcon on top of efifb" with
>> "fbcon on top of emulated-fbdev on top of simplekms" so as long
>> as the emulated-fbdev and simplekms code defer from say clearing
>> the screen to black, but keep it as is. Then the fb contents
>> should be preserved until fbcon decides to takeover the fbdev
>> and draw to it.
>>
>>>       * provide bootsplash DRM client
>>
>> Hmm, I guess this might be interesting for simple cases, but
>> although I would love to kill plymouth (I've become one of the
>> upstream maintainers for it) I'm afraid it is not that easy,
>> it does a bunch of stuff which will be tricky to do in the kernel:
>>
>> 1) Ask the user for diskcrypt passwords:
>> https://ic.pics.livejournal.com/hansdegoede/13347631/1496/1496_900.png
>>
>> 2) Show a nice splash + progressbar when installing updates in
>> offline updates mode:
>> https://ic.pics.livejournal.com/hansdegoede/13347631/899/899_900.png
>>
>> Still this would be nice for the non diskcrypt case I guess, then
>> we could not use plymouth during normal boot and only use it
>> for offline updates and it would also be nice for various embedded
>> cases.
>>
>> Regards,
>>
>> Hans
>>
>>
>>
>>
>>
>>>       * make simplekms usable with ARM-EFI fbs
>>>
>>> Thomas Zimmermann (9):
>>>    drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()
>>>    drm/format-helper: Add blitter functions
>>>    drm: Add simplekms driver
>>>    drm/simplekms: Add fbdev emulation
>>>    drm/simplekms: Initialize framebuffer data from device-tree node
>>>    drm/simplekms: Acquire clocks from DT device node
>>>    drm/simplekms: Acquire regulators from DT device node
>>>    drm: Add infrastructure for platform devices
>>>    drm/simplekms: Acquire memory aperture for framebuffer
>>>
>>>   MAINTAINERS                            |   6 +
>>>   drivers/gpu/drm/Kconfig                |   6 +
>>>   drivers/gpu/drm/Makefile               |   1 +
>>>   drivers/gpu/drm/drm_format_helper.c    |  96 ++-
>>>   drivers/gpu/drm/drm_platform.c         | 118 ++++
>>>   drivers/gpu/drm/mgag200/mgag200_mode.c |   2 +-
>>>   drivers/gpu/drm/tiny/Kconfig           |  17 +
>>>   drivers/gpu/drm/tiny/Makefile          |   1 +
>>>   drivers/gpu/drm/tiny/cirrus.c          |   2 +-
>>>   drivers/gpu/drm/tiny/simplekms.c       | 906 +++++++++++++++++++++++++
>>>   include/drm/drm_fb_helper.h            |  18 +-
>>>   include/drm/drm_format_helper.h        |  10 +-
>>>   include/drm/drm_platform.h             |  42 ++
>>>   13 files changed, 1217 insertions(+), 8 deletions(-)
>>>   create mode 100644 drivers/gpu/drm/drm_platform.c
>>>   create mode 100644 drivers/gpu/drm/tiny/simplekms.c
>>>   create mode 100644 include/drm/drm_platform.h
>>>
>>> --
>>> 2.27.0
>>>
>>
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Hans de Goede]

Hi,

On 7/1/20 4:10 PM, Thomas Zimmermann wrote:
> Hi Daniel,
> 
> thanks for reviewing most of the patchset.
> 
> Am 30.06.20 um 11:06 schrieb Daniel Vetter:
>> On Mon, Jun 29, 2020 at 11:39 AM Hans de Goede <hdegoede@redhat.com> wrote:
>>>
>>> Hi,
>>>
>>> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
>>>> This patchset adds support for simple-framebuffer platform devices and
>>>> a handover mechanism for native drivers to take-over control of the
>>>> hardware.
>>>>
>>>> The new driver, called simplekms, binds to a simple-frambuffer platform
>>>> device. The kernel's boot code creates such devices for firmware-provided
>>>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
>>>> loader sets up the framebuffers. Description via device tree is also an
>>>> option.
>>>>
>>>> Simplekms is small enough to be linked into the kernel. The driver's main
>>>> purpose is to provide graphical output during the early phases of the boot
>>>> process, before the native DRM drivers are available. Native drivers are
>>>> typically loaded from an initrd ram disk. Occationally simplekms can also
>>>> serve as interim solution on graphics hardware without native DRM driver.
>>>
>>> Cool, thank you for doing this, this is a very welcome change,
>>> but ... (see below).
>>>
>>>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
>>>> simplefb, for early-boot graphical output. However fbdev is deprecated and
>>>> the drivers do not provide DRM interfaces for modern userspace.
>>>>
>>>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
>>>>
>>>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
>>>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
>>>> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
>>>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
>>>> regulators. It's based on the simplefb drivers, but has been modified for
>>>> DRM.
>>>>
>>>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
>>>> framebuffer's I/O-memory range and provides a callback function to be
>>>> removed by a native driver. The native driver will remove simplekms before
>>>> taking over the hardware. The removal is integrated into existing helpers,
>>>> so drivers use it automatically.
>>>>
>>>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
>>>> reliably. The fbdev console and Weston work automatically. Xorg requires
>>>> manual configuration of the device. Xorgs current modesetting driver does
>>>> not work with both, platform and PCI device, for the same physical
>>>> hardware. Once configured, X11 works.
>>>
>>> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
>>> around and break userspace. OTOH this does seem like an userspace issue
>>> and not something which we can (or should try to) fix in the kernel.
>>>
>>> I guess the solution will have to be to have this default to N for now
>>> in Kconfig and clearly mention in the Kconfig help text that this needs
>>> a fixed Xorg modesetting driver before it can be enabled.
>>>
>>> Any chance you have time to work on fixing the Xorg modesetting driver
>>> so that this will just work with the standard Xorg autoconfiguration
>>> stuff?
>>
>> Hm, why do we even have both platform and pci drivers visible at the
>> same time? I thought the point of this is that simplekms is built-in,
>> then initrd loads the real drm driver, and by the time Xorg is
>> running, simplekms should be long gone.
>>
>> Maybe a few more details of what's going wrong and why to help unconfuse me?
> 
> I tested simplekms with PCI graphics cards.
> 
> Xorg does it's own scanning of the busses. It supports a platform bus,
> where it finds the simple-framebuffer device that is driven by
> simplekms. Xorg also scans the PCI bus, where is finds the native PCI
> device; usually driven by the native driver. It's the same hardware, but
> on different busses.
> 
> For each device, Xorg tries to configure a screen, the Xorg modeset
> driver tried to open the DRM device file and acquire DRM master status
> on it. This works for the first screen, but DRM master status can only
> be acquired once, so it fails for the second screen. Xorg then aborts
> and asks for manual configuration of the display device.
> 
> This can be solved by setting the platform device's bus id in the
> xorg.conf device section. It just doesn't happen automatically.
> 
> I found it hard to find a solution to this. Weston just opens a DRM
> device file and uses whatever it gets. Ideally, Xorg would do the same.
> That whole bus-scanning exercise gives it a wrong idea on which graphics
> devices are available.
> 
> One idea for a fix is to compare the device I/O-memory ranges and filter
> out duplicates on the Xorg modeset driver. I don't know how reliable
> this works in practice or if their are false positives.

I think that this should work nicely, although I wonder how Xorg will
get the memory-range for the simplefb platform device, it looks like
it will need to parse /dev/iomem for this, or we need to add a
new sysfs attr to the simplefb device for this. Adding the new sysfs
attr has the added bonus that we only enable the duplicate based
resource check for simplefb devices.

Hmm, I think we can actually fix this quite simply, for the platform
device, check the basename of where the
/sys/bus/platform/devices/XXXX/driver symlink points to and if it
is simplekms ignore it, assuming that there will be another PCI
or platform device which is the actual GPU.

I guess that might cause a problem where the output-device driven
through simplekms is not visible to Xorg in any other way, but
I don't think that that ever happens?  And even if it does, then it
is probably better to teach Xorg about it, since we likely want to
replace simplekms with a more full-featured driver at some point
anyways.

Can you try commenting out the platform bus scanning code in Xorg's
autoconfigure code and see if that fixes the no Xorg.conf case ?

If it does the driver symlink trick will probably fix 99.9 %
of all cases here, and we can worry about the others if we
ever encounter them.

> A more fundamental solution is to introduce a DRM bus in Xorg that
> enumerates all available DRM device files. If there are any, no other
> busses would be scanned.

That would break the case where there are 2 cards and 1 has a kms
driver and the other only supports fbdev. Admittedly this is a
corner case, but I do believe that we cannot just go and break this.

Regards,

Hans

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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 8065 bytes --]

Hi

Am 03.07.20 um 12:55 schrieb Hans de Goede:
> Hi,
> 
> On 7/1/20 4:10 PM, Thomas Zimmermann wrote:
>> Hi Daniel,
>>
>> thanks for reviewing most of the patchset.
>>
>> Am 30.06.20 um 11:06 schrieb Daniel Vetter:
>>> On Mon, Jun 29, 2020 at 11:39 AM Hans de Goede <hdegoede@redhat.com>
>>> wrote:
>>>>
>>>> Hi,
>>>>
>>>> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
>>>>> This patchset adds support for simple-framebuffer platform devices and
>>>>> a handover mechanism for native drivers to take-over control of the
>>>>> hardware.
>>>>>
>>>>> The new driver, called simplekms, binds to a simple-frambuffer
>>>>> platform
>>>>> device. The kernel's boot code creates such devices for
>>>>> firmware-provided
>>>>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or
>>>>> boot
>>>>> loader sets up the framebuffers. Description via device tree is
>>>>> also an
>>>>> option.
>>>>>
>>>>> Simplekms is small enough to be linked into the kernel. The
>>>>> driver's main
>>>>> purpose is to provide graphical output during the early phases of
>>>>> the boot
>>>>> process, before the native DRM drivers are available. Native
>>>>> drivers are
>>>>> typically loaded from an initrd ram disk. Occationally simplekms
>>>>> can also
>>>>> serve as interim solution on graphics hardware without native DRM
>>>>> driver.
>>>>
>>>> Cool, thank you for doing this, this is a very welcome change,
>>>> but ... (see below).
>>>>
>>>>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
>>>>> simplefb, for early-boot graphical output. However fbdev is
>>>>> deprecated and
>>>>> the drivers do not provide DRM interfaces for modern userspace.
>>>>>
>>>>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
>>>>>
>>>>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM
>>>>> helpers
>>>>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers.
>>>>> During
>>>>> pageflips, SHMEM buffers are copied into the framebuffer memory,
>>>>> similar
>>>>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
>>>>> regulators. It's based on the simplefb drivers, but has been
>>>>> modified for
>>>>> DRM.
>>>>>
>>>>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
>>>>> framebuffer's I/O-memory range and provides a callback function to be
>>>>> removed by a native driver. The native driver will remove simplekms
>>>>> before
>>>>> taking over the hardware. The removal is integrated into existing
>>>>> helpers,
>>>>> so drivers use it automatically.
>>>>>
>>>>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
>>>>> reliably. The fbdev console and Weston work automatically. Xorg
>>>>> requires
>>>>> manual configuration of the device. Xorgs current modesetting
>>>>> driver does
>>>>> not work with both, platform and PCI device, for the same physical
>>>>> hardware. Once configured, X11 works.
>>>>
>>>> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
>>>> around and break userspace. OTOH this does seem like an userspace issue
>>>> and not something which we can (or should try to) fix in the kernel.
>>>>
>>>> I guess the solution will have to be to have this default to N for now
>>>> in Kconfig and clearly mention in the Kconfig help text that this needs
>>>> a fixed Xorg modesetting driver before it can be enabled.
>>>>
>>>> Any chance you have time to work on fixing the Xorg modesetting driver
>>>> so that this will just work with the standard Xorg autoconfiguration
>>>> stuff?
>>>
>>> Hm, why do we even have both platform and pci drivers visible at the
>>> same time? I thought the point of this is that simplekms is built-in,
>>> then initrd loads the real drm driver, and by the time Xorg is
>>> running, simplekms should be long gone.
>>>
>>> Maybe a few more details of what's going wrong and why to help
>>> unconfuse me?
>>
>> I tested simplekms with PCI graphics cards.
>>
>> Xorg does it's own scanning of the busses. It supports a platform bus,
>> where it finds the simple-framebuffer device that is driven by
>> simplekms. Xorg also scans the PCI bus, where is finds the native PCI
>> device; usually driven by the native driver. It's the same hardware, but
>> on different busses.
>>
>> For each device, Xorg tries to configure a screen, the Xorg modeset
>> driver tried to open the DRM device file and acquire DRM master status
>> on it. This works for the first screen, but DRM master status can only
>> be acquired once, so it fails for the second screen. Xorg then aborts
>> and asks for manual configuration of the display device.
>>
>> This can be solved by setting the platform device's bus id in the
>> xorg.conf device section. It just doesn't happen automatically.
>>
>> I found it hard to find a solution to this. Weston just opens a DRM
>> device file and uses whatever it gets. Ideally, Xorg would do the same.
>> That whole bus-scanning exercise gives it a wrong idea on which graphics
>> devices are available.
>>
>> One idea for a fix is to compare the device I/O-memory ranges and filter
>> out duplicates on the Xorg modeset driver. I don't know how reliable
>> this works in practice or if their are false positives.
> 
> I think that this should work nicely, although I wonder how Xorg will
> get the memory-range for the simplefb platform device, it looks like
> it will need to parse /dev/iomem for this, or we need to add a
> new sysfs attr to the simplefb device for this. Adding the new sysfs
> attr has the added bonus that we only enable the duplicate based
> resource check for simplefb devices.
> 
> Hmm, I think we can actually fix this quite simply, for the platform
> device, check the basename of where the
> /sys/bus/platform/devices/XXXX/driver symlink points to and if it
> is simplekms ignore it, assuming that there will be another PCI
> or platform device which is the actual GPU.

That probably would not work. On aarch64, we (SUSE) utilize EFI via
grub-privided efi stubs (as far as i understand). This allows us to use
the kernel's efifb driver for boot-up graphics. But there's no PCI bus
on most of these systems. I don't think Xorg could rely on that.

> 
> I guess that might cause a problem where the output-device driven
> through simplekms is not visible to Xorg in any other way, but
> I don't think that that ever happens?  And even if it does, then it
> is probably better to teach Xorg about it, since we likely want to
> replace simplekms with a more full-featured driver at some point
> anyways.
> 
> Can you try commenting out the platform bus scanning code in Xorg's
> autoconfigure code and see if that fixes the no Xorg.conf case ?

That works to some extent. Xorg drivers provide a bus-specific probe
function. Returning false from the platform-probe function in the Xorg
modesetting driver makes the PCI side work on top of simplekms.

Returning false from the Xorg driver's PCI-probe function does not work
however. It's some Xorg weirdness, I guess.

What I'd want is to accept the platform device, but later fails for the
PCI device.

> 
> If it does the driver symlink trick will probably fix 99.9 %
> of all cases here, and we can worry about the others if we
> ever encounter them.
> 
>> A more fundamental solution is to introduce a DRM bus in Xorg that
>> enumerates all available DRM device files. If there are any, no other
>> busses would be scanned.
> 
> That would break the case where there are 2 cards and 1 has a kms
> driver and the other only supports fbdev. Admittedly this is a
> corner case, but I do believe that we cannot just go and break this.

Yep, that was my concern.

Best regards
Thomas

> 
> Regards,
> 
> Hans
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Daniel Vetter]

On Fri, Jul 3, 2020 at 12:55 PM Hans de Goede <hdegoede@redhat.com> wrote:
>
> Hi,
>
> On 7/1/20 4:10 PM, Thomas Zimmermann wrote:
> > Hi Daniel,
> >
> > thanks for reviewing most of the patchset.
> >
> > Am 30.06.20 um 11:06 schrieb Daniel Vetter:
> >> On Mon, Jun 29, 2020 at 11:39 AM Hans de Goede <hdegoede@redhat.com> wrote:
> >>>
> >>> Hi,
> >>>
> >>> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
> >>>> This patchset adds support for simple-framebuffer platform devices and
> >>>> a handover mechanism for native drivers to take-over control of the
> >>>> hardware.
> >>>>
> >>>> The new driver, called simplekms, binds to a simple-frambuffer platform
> >>>> device. The kernel's boot code creates such devices for firmware-provided
> >>>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
> >>>> loader sets up the framebuffers. Description via device tree is also an
> >>>> option.
> >>>>
> >>>> Simplekms is small enough to be linked into the kernel. The driver's main
> >>>> purpose is to provide graphical output during the early phases of the boot
> >>>> process, before the native DRM drivers are available. Native drivers are
> >>>> typically loaded from an initrd ram disk. Occationally simplekms can also
> >>>> serve as interim solution on graphics hardware without native DRM driver.
> >>>
> >>> Cool, thank you for doing this, this is a very welcome change,
> >>> but ... (see below).
> >>>
> >>>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
> >>>> simplefb, for early-boot graphical output. However fbdev is deprecated and
> >>>> the drivers do not provide DRM interfaces for modern userspace.
> >>>>
> >>>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
> >>>>
> >>>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
> >>>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
> >>>> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
> >>>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
> >>>> regulators. It's based on the simplefb drivers, but has been modified for
> >>>> DRM.
> >>>>
> >>>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
> >>>> framebuffer's I/O-memory range and provides a callback function to be
> >>>> removed by a native driver. The native driver will remove simplekms before
> >>>> taking over the hardware. The removal is integrated into existing helpers,
> >>>> so drivers use it automatically.
> >>>>
> >>>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
> >>>> reliably. The fbdev console and Weston work automatically. Xorg requires
> >>>> manual configuration of the device. Xorgs current modesetting driver does
> >>>> not work with both, platform and PCI device, for the same physical
> >>>> hardware. Once configured, X11 works.
> >>>
> >>> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
> >>> around and break userspace. OTOH this does seem like an userspace issue
> >>> and not something which we can (or should try to) fix in the kernel.
> >>>
> >>> I guess the solution will have to be to have this default to N for now
> >>> in Kconfig and clearly mention in the Kconfig help text that this needs
> >>> a fixed Xorg modesetting driver before it can be enabled.
> >>>
> >>> Any chance you have time to work on fixing the Xorg modesetting driver
> >>> so that this will just work with the standard Xorg autoconfiguration
> >>> stuff?
> >>
> >> Hm, why do we even have both platform and pci drivers visible at the
> >> same time? I thought the point of this is that simplekms is built-in,
> >> then initrd loads the real drm driver, and by the time Xorg is
> >> running, simplekms should be long gone.
> >>
> >> Maybe a few more details of what's going wrong and why to help unconfuse me?
> >
> > I tested simplekms with PCI graphics cards.
> >
> > Xorg does it's own scanning of the busses. It supports a platform bus,
> > where it finds the simple-framebuffer device that is driven by
> > simplekms. Xorg also scans the PCI bus, where is finds the native PCI
> > device; usually driven by the native driver. It's the same hardware, but
> > on different busses.
> >
> > For each device, Xorg tries to configure a screen, the Xorg modeset
> > driver tried to open the DRM device file and acquire DRM master status
> > on it. This works for the first screen, but DRM master status can only
> > be acquired once, so it fails for the second screen. Xorg then aborts
> > and asks for manual configuration of the display device.
> >
> > This can be solved by setting the platform device's bus id in the
> > xorg.conf device section. It just doesn't happen automatically.
> >
> > I found it hard to find a solution to this. Weston just opens a DRM
> > device file and uses whatever it gets. Ideally, Xorg would do the same.
> > That whole bus-scanning exercise gives it a wrong idea on which graphics
> > devices are available.
> >
> > One idea for a fix is to compare the device I/O-memory ranges and filter
> > out duplicates on the Xorg modeset driver. I don't know how reliable
> > this works in practice or if their are false positives.
>
> I think that this should work nicely, although I wonder how Xorg will
> get the memory-range for the simplefb platform device, it looks like
> it will need to parse /dev/iomem for this, or we need to add a
> new sysfs attr to the simplefb device for this. Adding the new sysfs
> attr has the added bonus that we only enable the duplicate based
> resource check for simplefb devices.

Uh why exactly does Xorg even need to do all this parsing? We're not
in a ums world anymore ...

Also, you'll never have a simplekms driver _and_ the real drm driver
bound at the same time, that's a kernel bug.

Really all this bus scanning is vestiges in Xorg from the old pre-kms
days, and there's no point. Scan all drm device nodes (not physical
devices) like anything remotely modern, and it's all good. Maybe that
means Xorg needs a drm bus to fit into this world, and only if that
gives you nothing, fall back to the historical real bus scanning.

> Hmm, I think we can actually fix this quite simply, for the platform
> device, check the basename of where the
> /sys/bus/platform/devices/XXXX/driver symlink points to and if it
> is simplekms ignore it, assuming that there will be another PCI
> or platform device which is the actual GPU.

Again, you're not going to have simplekms and the real driver bound at
the same time. Kernel guarantees that. Userspace isn't in the business
of second-guessing the kernel's device model, that only leads to pain
like the one we have here, were Xorg can't both use platform and pci
devices for some oddball reason :-/

> I guess that might cause a problem where the output-device driven
> through simplekms is not visible to Xorg in any other way, but
> I don't think that that ever happens?  And even if it does, then it
> is probably better to teach Xorg about it, since we likely want to
> replace simplekms with a more full-featured driver at some point
> anyways.
>
> Can you try commenting out the platform bus scanning code in Xorg's
> autoconfigure code and see if that fixes the no Xorg.conf case ?
>
> If it does the driver symlink trick will probably fix 99.9 %
> of all cases here, and we can worry about the others if we
> ever encounter them.
>
> > A more fundamental solution is to introduce a DRM bus in Xorg that
> > enumerates all available DRM device files. If there are any, no other
> > busses would be scanned.
>
> That would break the case where there are 2 cards and 1 has a kms
> driver and the other only supports fbdev. Admittedly this is a
> corner case, but I do believe that we cannot just go and break this.

Yeah but even for this case can't Xorg simply first scan drm drivers,
and then fbdev drivers (excluding the drm ones, that's pretty easy to
do since they're both bound to the same physical device in sysfs). Not
magic guesses at how the platform model works.

Also, we don't have to make this work with current Xorg code, since
it's a new driver that distros need to enable explicitly. So fixing
Xorg should be on the table.

Or we just forget about Xorg, and tell distros that this only works if
they have a reasonable wayland compositor that doesn't have an entire
hand-rolled device model.

-Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Hans de Goede]

Hi,

On 7/3/20 2:58 PM, Daniel Vetter wrote:
> On Fri, Jul 3, 2020 at 12:55 PM Hans de Goede <hdegoede@redhat.com> wrote:
>>
>> Hi,
>>
>> On 7/1/20 4:10 PM, Thomas Zimmermann wrote:
>>> Hi Daniel,
>>>
>>> thanks for reviewing most of the patchset.
>>>
>>> Am 30.06.20 um 11:06 schrieb Daniel Vetter:
>>>> On Mon, Jun 29, 2020 at 11:39 AM Hans de Goede <hdegoede@redhat.com> wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
>>>>>> This patchset adds support for simple-framebuffer platform devices and
>>>>>> a handover mechanism for native drivers to take-over control of the
>>>>>> hardware.
>>>>>>
>>>>>> The new driver, called simplekms, binds to a simple-frambuffer platform
>>>>>> device. The kernel's boot code creates such devices for firmware-provided
>>>>>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
>>>>>> loader sets up the framebuffers. Description via device tree is also an
>>>>>> option.
>>>>>>
>>>>>> Simplekms is small enough to be linked into the kernel. The driver's main
>>>>>> purpose is to provide graphical output during the early phases of the boot
>>>>>> process, before the native DRM drivers are available. Native drivers are
>>>>>> typically loaded from an initrd ram disk. Occationally simplekms can also
>>>>>> serve as interim solution on graphics hardware without native DRM driver.
>>>>>
>>>>> Cool, thank you for doing this, this is a very welcome change,
>>>>> but ... (see below).
>>>>>
>>>>>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
>>>>>> simplefb, for early-boot graphical output. However fbdev is deprecated and
>>>>>> the drivers do not provide DRM interfaces for modern userspace.
>>>>>>
>>>>>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
>>>>>>
>>>>>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
>>>>>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
>>>>>> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
>>>>>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
>>>>>> regulators. It's based on the simplefb drivers, but has been modified for
>>>>>> DRM.
>>>>>>
>>>>>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
>>>>>> framebuffer's I/O-memory range and provides a callback function to be
>>>>>> removed by a native driver. The native driver will remove simplekms before
>>>>>> taking over the hardware. The removal is integrated into existing helpers,
>>>>>> so drivers use it automatically.
>>>>>>
>>>>>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
>>>>>> reliably. The fbdev console and Weston work automatically. Xorg requires
>>>>>> manual configuration of the device. Xorgs current modesetting driver does
>>>>>> not work with both, platform and PCI device, for the same physical
>>>>>> hardware. Once configured, X11 works.
>>>>>
>>>>> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
>>>>> around and break userspace. OTOH this does seem like an userspace issue
>>>>> and not something which we can (or should try to) fix in the kernel.
>>>>>
>>>>> I guess the solution will have to be to have this default to N for now
>>>>> in Kconfig and clearly mention in the Kconfig help text that this needs
>>>>> a fixed Xorg modesetting driver before it can be enabled.
>>>>>
>>>>> Any chance you have time to work on fixing the Xorg modesetting driver
>>>>> so that this will just work with the standard Xorg autoconfiguration
>>>>> stuff?
>>>>
>>>> Hm, why do we even have both platform and pci drivers visible at the
>>>> same time? I thought the point of this is that simplekms is built-in,
>>>> then initrd loads the real drm driver, and by the time Xorg is
>>>> running, simplekms should be long gone.
>>>>
>>>> Maybe a few more details of what's going wrong and why to help unconfuse me?
>>>
>>> I tested simplekms with PCI graphics cards.
>>>
>>> Xorg does it's own scanning of the busses. It supports a platform bus,
>>> where it finds the simple-framebuffer device that is driven by
>>> simplekms. Xorg also scans the PCI bus, where is finds the native PCI
>>> device; usually driven by the native driver. It's the same hardware, but
>>> on different busses.
>>>
>>> For each device, Xorg tries to configure a screen, the Xorg modeset
>>> driver tried to open the DRM device file and acquire DRM master status
>>> on it. This works for the first screen, but DRM master status can only
>>> be acquired once, so it fails for the second screen. Xorg then aborts
>>> and asks for manual configuration of the display device.
>>>
>>> This can be solved by setting the platform device's bus id in the
>>> xorg.conf device section. It just doesn't happen automatically.
>>>
>>> I found it hard to find a solution to this. Weston just opens a DRM
>>> device file and uses whatever it gets. Ideally, Xorg would do the same.
>>> That whole bus-scanning exercise gives it a wrong idea on which graphics
>>> devices are available.
>>>
>>> One idea for a fix is to compare the device I/O-memory ranges and filter
>>> out duplicates on the Xorg modeset driver. I don't know how reliable
>>> this works in practice or if their are false positives.
>>
>> I think that this should work nicely, although I wonder how Xorg will
>> get the memory-range for the simplefb platform device, it looks like
>> it will need to parse /dev/iomem for this, or we need to add a
>> new sysfs attr to the simplefb device for this. Adding the new sysfs
>> attr has the added bonus that we only enable the duplicate based
>> resource check for simplefb devices.
> 
> Uh why exactly does Xorg even need to do all this parsing? We're not
> in a ums world anymore ...
> 
> Also, you'll never have a simplekms driver _and_ the real drm driver
> bound at the same time, that's a kernel bug.
> 
> Really all this bus scanning is vestiges in Xorg from the old pre-kms
> days, and there's no point. Scan all drm device nodes (not physical
> devices) like anything remotely modern, and it's all good. Maybe that
> means Xorg needs a drm bus to fit into this world, and only if that
> gives you nothing, fall back to the historical real bus scanning.
> 
>> Hmm, I think we can actually fix this quite simply, for the platform
>> device, check the basename of where the
>> /sys/bus/platform/devices/XXXX/driver symlink points to and if it
>> is simplekms ignore it, assuming that there will be another PCI
>> or platform device which is the actual GPU.
> 
> Again, you're not going to have simplekms and the real driver bound at
> the same time. Kernel guarantees that. Userspace isn't in the business
> of second-guessing the kernel's device model, that only leads to pain
> like the one we have here, were Xorg can't both use platform and pci
> devices for some oddball reason :-/
> 
>> I guess that might cause a problem where the output-device driven
>> through simplekms is not visible to Xorg in any other way, but
>> I don't think that that ever happens?  And even if it does, then it
>> is probably better to teach Xorg about it, since we likely want to
>> replace simplekms with a more full-featured driver at some point
>> anyways.
>>
>> Can you try commenting out the platform bus scanning code in Xorg's
>> autoconfigure code and see if that fixes the no Xorg.conf case ?
>>
>> If it does the driver symlink trick will probably fix 99.9 %
>> of all cases here, and we can worry about the others if we
>> ever encounter them.
>>
>>> A more fundamental solution is to introduce a DRM bus in Xorg that
>>> enumerates all available DRM device files. If there are any, no other
>>> busses would be scanned.
>>
>> That would break the case where there are 2 cards and 1 has a kms
>> driver and the other only supports fbdev. Admittedly this is a
>> corner case, but I do believe that we cannot just go and break this.
> 
> Yeah but even for this case can't Xorg simply first scan drm drivers,
> and then fbdev drivers (excluding the drm ones, that's pretty easy to
> do since they're both bound to the same physical device in sysfs). Not
> magic guesses at how the platform model works.

Right, I guess the Xorg scanning architecture here still comes from
the era where we had userspace mode-setting.

> Also, we don't have to make this work with current Xorg code, since
> it's a new driver that distros need to enable explicitly. So fixing
> Xorg should be on the table.

Ack.

> Or we just forget about Xorg, and tell distros that this only works if
> they have a reasonable wayland compositor that doesn't have an entire
> hand-rolled device model.

Yeah I don't think that is going to fly.

Regards,

Hans

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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 8646 bytes --]

Hi Hans

Am 29.06.20 um 11:38 schrieb Hans de Goede:
> Hi,
> 
> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
>> This patchset adds support for simple-framebuffer platform devices and
>> a handover mechanism for native drivers to take-over control of the
>> hardware.
>>
>> The new driver, called simplekms, binds to a simple-frambuffer platform
>> device. The kernel's boot code creates such devices for firmware-provided
>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
>> loader sets up the framebuffers. Description via device tree is also an
>> option.
>>
>> Simplekms is small enough to be linked into the kernel. The driver's main
>> purpose is to provide graphical output during the early phases of the
>> boot
>> process, before the native DRM drivers are available. Native drivers are
>> typically loaded from an initrd ram disk. Occationally simplekms can also
>> serve as interim solution on graphics hardware without native DRM driver.
> 
> Cool, thank you for doing this, this is a very welcome change,
> but ... (see below).
> 
>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
>> simplefb, for early-boot graphical output. However fbdev is deprecated
>> and
>> the drivers do not provide DRM interfaces for modern userspace.
>>
>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
>>
>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
>> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
>> regulators. It's based on the simplefb drivers, but has been modified for
>> DRM.
>>
>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
>> framebuffer's I/O-memory range and provides a callback function to be
>> removed by a native driver. The native driver will remove simplekms
>> before
>> taking over the hardware. The removal is integrated into existing
>> helpers,
>> so drivers use it automatically.
>>
>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
>> reliably. The fbdev console and Weston work automatically. Xorg requires
>> manual configuration of the device. Xorgs current modesetting driver does
>> not work with both, platform and PCI device, for the same physical
>> hardware. Once configured, X11 works.
> 
> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
> around and break userspace. OTOH this does seem like an userspace issue
> and not something which we can (or should try to) fix in the kernel.

Xorg is an important use case, but simplekms does not "break userspace."
If you're not using simplekms, nothing changes; if simplekms is replaced
by the native driver, nothing changes. Simplekms works with Xorg of the
device is auto-configured. Xorg is not able to auto-configure simplekms
devices ATM.

> 
> I guess the solution will have to be to have this default to N for now
> in Kconfig and clearly mention in the Kconfig help text that this needs
> a fixed Xorg modesetting driver before it can be enabled.

Sure, but simplekms is just a driver. Shouldn't it default to N anyway?

> 
> Any chance you have time to work on fixing the Xorg modesetting driver
> so that this will just work with the standard Xorg autoconfiguration
> stuff?

I'll do if somehow possible. See my reply to Daniel for a description of
the problem.

> 
>> One cosmetical issue is that simplekms's device file is card0 and the
>> native driver's device file is card1. After simplekms has been kicked
>> out,
>> only card1 is left. This does not seem to be a practical problem however.
>>
>> TODO/IDEAS:
>>
>>     * provide deferred takeover
> 
> I assume you mean akin to CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER ?
> I don't think you need to do anything for that, as long as you just
> leave the fb contents intact until requested to change it.

Great. If it's that easy; even better.

> 
> Right now with flickerfree boot we have fbcon on top of efifb and
> efifb does not do anything special wrt
> CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
> ATM it does draw/restore the ACPI BGRT logo since since some firmwares
> don't draw that themselves, but that is not necessary in most cases
> and other then that all the deferred takeover magic is in the fbcon
> code, it does not bind to the fbdev (and thus does not draw to it)
> until the first time the kernel tries to output text to the console,
> together with the "quiet" kernel commandline argument that ensures
> that the fb is kept unmodified until e.g. a panic happens.
> 
> With simplekms we would replace "fbcon on top of efifb" with
> "fbcon on top of emulated-fbdev on top of simplekms" so as long
> as the emulated-fbdev and simplekms code defer from say clearing
> the screen to black, but keep it as is. Then the fb contents
> should be preserved until fbcon decides to takeover the fbdev
> and draw to it.
> 
>>     * provide bootsplash DRM client
> 
> Hmm, I guess this might be interesting for simple cases, but
> although I would love to kill plymouth (I've become one of the
> upstream maintainers for it) I'm afraid it is not that easy,
> it does a bunch of stuff which will be tricky to do in the kernel:

The whole bootsplash thing is really a follow-up project.

What I have in mind for the bootsplash is the ACPI BGRT logo restoration
that is currently in efifb. Maybe other sources for boot logos could be
considered as well. And if nothing else, it could show a penguin. As
soon as plymouth is ready, it would take over the display and do its thing.

Noralf made a prototype of an in-kernel bootsplash client that displays
a colored rectangle. That's already half of the work, I guess.

Best regards
Thomas

> 
> 1) Ask the user for diskcrypt passwords:
> https://ic.pics.livejournal.com/hansdegoede/13347631/1496/1496_900.png
> 
> 2) Show a nice splash + progressbar when installing updates in
> offline updates mode:
> https://ic.pics.livejournal.com/hansdegoede/13347631/899/899_900.png
> 
> Still this would be nice for the non diskcrypt case I guess, then
> we could not use plymouth during normal boot and only use it
> for offline updates and it would also be nice for various embedded
> cases.
> 
> Regards,
> 
> Hans
> 
> 
> 
> 
> 
>>     * make simplekms usable with ARM-EFI fbs
>>
>> Thomas Zimmermann (9):
>>    drm/format-helper: Pass destination pitch to drm_fb_memcpy_dstclip()
>>    drm/format-helper: Add blitter functions
>>    drm: Add simplekms driver
>>    drm/simplekms: Add fbdev emulation
>>    drm/simplekms: Initialize framebuffer data from device-tree node
>>    drm/simplekms: Acquire clocks from DT device node
>>    drm/simplekms: Acquire regulators from DT device node
>>    drm: Add infrastructure for platform devices
>>    drm/simplekms: Acquire memory aperture for framebuffer
>>
>>   MAINTAINERS                            |   6 +
>>   drivers/gpu/drm/Kconfig                |   6 +
>>   drivers/gpu/drm/Makefile               |   1 +
>>   drivers/gpu/drm/drm_format_helper.c    |  96 ++-
>>   drivers/gpu/drm/drm_platform.c         | 118 ++++
>>   drivers/gpu/drm/mgag200/mgag200_mode.c |   2 +-
>>   drivers/gpu/drm/tiny/Kconfig           |  17 +
>>   drivers/gpu/drm/tiny/Makefile          |   1 +
>>   drivers/gpu/drm/tiny/cirrus.c          |   2 +-
>>   drivers/gpu/drm/tiny/simplekms.c       | 906 +++++++++++++++++++++++++
>>   include/drm/drm_fb_helper.h            |  18 +-
>>   include/drm/drm_format_helper.h        |  10 +-
>>   include/drm/drm_platform.h             |  42 ++
>>   13 files changed, 1217 insertions(+), 8 deletions(-)
>>   create mode 100644 drivers/gpu/drm/drm_platform.c
>>   create mode 100644 drivers/gpu/drm/tiny/simplekms.c
>>   create mode 100644 include/drm/drm_platform.h
>>
>> -- 
>> 2.27.0
>>
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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Re: [RFC][PATCH 0/9] drm: Support simple-framebuffer devices and firmware fbs

[Hans de Goede]

Hi,

On 7/1/20 3:48 PM, Thomas Zimmermann wrote:
> Hi Hans
> 
> Am 29.06.20 um 11:38 schrieb Hans de Goede:
>> Hi,
>>
>> On 6/25/20 2:00 PM, Thomas Zimmermann wrote:
>>> This patchset adds support for simple-framebuffer platform devices and
>>> a handover mechanism for native drivers to take-over control of the
>>> hardware.
>>>
>>> The new driver, called simplekms, binds to a simple-frambuffer platform
>>> device. The kernel's boot code creates such devices for firmware-provided
>>> framebuffers, such as EFI-GOP or VESA. Typically the BIOS, UEFI or boot
>>> loader sets up the framebuffers. Description via device tree is also an
>>> option.
>>>
>>> Simplekms is small enough to be linked into the kernel. The driver's main
>>> purpose is to provide graphical output during the early phases of the
>>> boot
>>> process, before the native DRM drivers are available. Native drivers are
>>> typically loaded from an initrd ram disk. Occationally simplekms can also
>>> serve as interim solution on graphics hardware without native DRM driver.
>>
>> Cool, thank you for doing this, this is a very welcome change,
>> but ... (see below).
>>
>>> So far distributions rely on fbdev drivers, such as efifb, vesafb or
>>> simplefb, for early-boot graphical output. However fbdev is deprecated
>>> and
>>> the drivers do not provide DRM interfaces for modern userspace.
>>>
>>> Patches 1 and 2 prepare the DRM format helpers for simplekms.
>>>
>>> Patches 3 to 7 add the simplekms driver. It's build on simple DRM helpers
>>> and SHMEM. It supports 16-bit, 24-bit and 32-bit RGB framebuffers. During
>>> pageflips, SHMEM buffers are copied into the framebuffer memory, similar
>>> to cirrus or mgag200. The code in patches 6 and 7 handles clocks and
>>> regulators. It's based on the simplefb drivers, but has been modified for
>>> DRM.
>>>
>>> Patches 8 and 9 add a hand-over mechanism. Simplekms acquires it's
>>> framebuffer's I/O-memory range and provides a callback function to be
>>> removed by a native driver. The native driver will remove simplekms
>>> before
>>> taking over the hardware. The removal is integrated into existing
>>> helpers,
>>> so drivers use it automatically.
>>>
>>> I tested simplekms with x86 EFI and VESA framebuffers, which both work
>>> reliably. The fbdev console and Weston work automatically. Xorg requires
>>> manual configuration of the device. Xorgs current modesetting driver does
>>> not work with both, platform and PCI device, for the same physical
>>> hardware. Once configured, X11 works.
>>
>> Ugh, Xorg not working OOTB is a bit of a showstopper, we cannot just go
>> around and break userspace. OTOH this does seem like an userspace issue
>> and not something which we can (or should try to) fix in the kernel.
> 
> Xorg is an important use case, but simplekms does not "break userspace."
> If you're not using simplekms, nothing changes; if simplekms is replaced
> by the native driver, nothing changes. Simplekms works with Xorg of the
> device is auto-configured. Xorg is not able to auto-configure simplekms
> devices ATM.

As I already mentioned in my replay to Daniel: If there is no native driver,
or the native driver fails to load (e.g. nvidia binary driver dkms build
fails with a nwer kernel) then having simplekms enables changes the user,
experience from Xorg on fbdev, slow but usable to search for a solution
to no GUI. I agree that we cannot solve this on the kernel side, but it
is a real problem which we need to keep in mind.

>> I guess the solution will have to be to have this default to N for now
>> in Kconfig and clearly mention in the Kconfig help text that this needs
>> a fixed Xorg modesetting driver before it can be enabled.
> 
> Sure, but simplekms is just a driver. Shouldn't it default to N anyway?

I guess so.

>> Any chance you have time to work on fixing the Xorg modesetting driver
>> so that this will just work with the standard Xorg autoconfiguration
>> stuff?
> 
> I'll do if somehow possible. See my reply to Daniel for a description of
> the problem.

Great.

>>> One cosmetical issue is that simplekms's device file is card0 and the
>>> native driver's device file is card1. After simplekms has been kicked
>>> out,
>>> only card1 is left. This does not seem to be a practical problem however.
>>>
>>> TODO/IDEAS:
>>>
>>>      * provide deferred takeover
>>
>> I assume you mean akin to CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER ?
>> I don't think you need to do anything for that, as long as you just
>> leave the fb contents intact until requested to change it.
> 
> Great. If it's that easy; even better.
> 
>>
>> Right now with flickerfree boot we have fbcon on top of efifb and
>> efifb does not do anything special wrt
>> CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
>> ATM it does draw/restore the ACPI BGRT logo since since some firmwares
>> don't draw that themselves, but that is not necessary in most cases
>> and other then that all the deferred takeover magic is in the fbcon
>> code, it does not bind to the fbdev (and thus does not draw to it)
>> until the first time the kernel tries to output text to the console,
>> together with the "quiet" kernel commandline argument that ensures
>> that the fb is kept unmodified until e.g. a panic happens.
>>
>> With simplekms we would replace "fbcon on top of efifb" with
>> "fbcon on top of emulated-fbdev on top of simplekms" so as long
>> as the emulated-fbdev and simplekms code defer from say clearing
>> the screen to black, but keep it as is. Then the fb contents
>> should be preserved until fbcon decides to takeover the fbdev
>> and draw to it.
>>
>>>      * provide bootsplash DRM client
>>
>> Hmm, I guess this might be interesting for simple cases, but
>> although I would love to kill plymouth (I've become one of the
>> upstream maintainers for it) I'm afraid it is not that easy,
>> it does a bunch of stuff which will be tricky to do in the kernel:
> 
> The whole bootsplash thing is really a follow-up project.
> 
> What I have in mind for the bootsplash is the ACPI BGRT logo restoration
> that is currently in efifb. Maybe other sources for boot logos could be
> considered as well. And if nothing else, it could show a penguin. As
> soon as plymouth is ready, it would take over the display and do its thing.
> 
> Noralf made a prototype of an in-kernel bootsplash client that displays
> a colored rectangle. That's already half of the work, I guess.

Ok, this sounds good.

Regards,

Hans

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