From: Thomas Zimmermann <tzimmermann@suse.de>
To: Lucas Stach <l.stach@pengutronix.de>,
linux+etnaviv@armlinux.org.uk, christian.gmeiner@gmail.com,
airlied@linux.ie, daniel@ffwll.ch
Cc: etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/etnaviv: Implement mmap as GEM object function
Date: Thu, 24 Jun 2021 14:22:25 +0200 [thread overview]
Message-ID: <42715b01-9944-ef8e-b41a-895d60a7ba09@suse.de> (raw)
In-Reply-To: <d31b8b5237695d9bea3ad52b9be410249d12d652.camel@pengutronix.de>
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Am 24.06.21 um 12:50 schrieb Lucas Stach:
> Am Donnerstag, dem 24.06.2021 um 12:47 +0200 schrieb Thomas Zimmermann:
>> Hi
>>
>> Am 24.06.21 um 11:11 schrieb Lucas Stach:
>>> Am Donnerstag, dem 24.06.2021 um 10:58 +0200 schrieb Thomas Zimmermann:
>>>> Moving the driver-specific mmap code into a GEM object function allows
>>>> for using DRM helpers for various mmap callbacks.
>>>>
>>>> The respective etnaviv functions are being removed. The file_operations
>>>> structure fops is now being created by the helper macro
>>>> DEFINE_DRM_GEM_FOPS().
>>>>
>>>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>>>> ---
>>>> drivers/gpu/drm/etnaviv/etnaviv_drv.c | 14 ++------------
>>>> drivers/gpu/drm/etnaviv/etnaviv_drv.h | 3 ---
>>>> drivers/gpu/drm/etnaviv/etnaviv_gem.c | 18 +++++-------------
>>>> drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c | 13 -------------
>>>> 4 files changed, 7 insertions(+), 41 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.c b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
>>>> index f0a07278ad04..7dcc6392792d 100644
>>>> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.c
>>>> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.c
>>>> @@ -468,17 +468,7 @@ static const struct drm_ioctl_desc etnaviv_ioctls[] = {
>>>> ETNA_IOCTL(PM_QUERY_SIG, pm_query_sig, DRM_RENDER_ALLOW),
>>>> };
>>>>
>>>> -static const struct file_operations fops = {
>>>> - .owner = THIS_MODULE,
>>>> - .open = drm_open,
>>>> - .release = drm_release,
>>>> - .unlocked_ioctl = drm_ioctl,
>>>> - .compat_ioctl = drm_compat_ioctl,
>>>> - .poll = drm_poll,
>>>> - .read = drm_read,
>>>> - .llseek = no_llseek,
>>>> - .mmap = etnaviv_gem_mmap,
>>>> -};
>>>> +DEFINE_DRM_GEM_FOPS(fops);
>>>>
>>>> static const struct drm_driver etnaviv_drm_driver = {
>>>> .driver_features = DRIVER_GEM | DRIVER_RENDER,
>>>> @@ -487,7 +477,7 @@ static const struct drm_driver etnaviv_drm_driver = {
>>>> .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
>>>> .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
>>>> .gem_prime_import_sg_table = etnaviv_gem_prime_import_sg_table,
>>>> - .gem_prime_mmap = etnaviv_gem_prime_mmap,
>>>> + .gem_prime_mmap = drm_gem_prime_mmap,
>>>> #ifdef CONFIG_DEBUG_FS
>>>> .debugfs_init = etnaviv_debugfs_init,
>>>> #endif
>>>> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_drv.h b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
>>>> index 003288ebd896..049ae87de9be 100644
>>>> --- a/drivers/gpu/drm/etnaviv/etnaviv_drv.h
>>>> +++ b/drivers/gpu/drm/etnaviv/etnaviv_drv.h
>>>> @@ -47,12 +47,9 @@ struct etnaviv_drm_private {
>>>> int etnaviv_ioctl_gem_submit(struct drm_device *dev, void *data,
>>>> struct drm_file *file);
>>>>
>>>> -int etnaviv_gem_mmap(struct file *filp, struct vm_area_struct *vma);
>>>> int etnaviv_gem_mmap_offset(struct drm_gem_object *obj, u64 *offset);
>>>> struct sg_table *etnaviv_gem_prime_get_sg_table(struct drm_gem_object *obj);
>>>> int etnaviv_gem_prime_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
>>>> -int etnaviv_gem_prime_mmap(struct drm_gem_object *obj,
>>>> - struct vm_area_struct *vma);
>>>> struct drm_gem_object *etnaviv_gem_prime_import_sg_table(struct drm_device *dev,
>>>> struct dma_buf_attachment *attach, struct sg_table *sg);
>>>> int etnaviv_gem_prime_pin(struct drm_gem_object *obj);
>>>> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_gem.c b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
>>>> index b8fa6ed3dd73..8f1b5af47dd6 100644
>>>> --- a/drivers/gpu/drm/etnaviv/etnaviv_gem.c
>>>> +++ b/drivers/gpu/drm/etnaviv/etnaviv_gem.c
>>>> @@ -130,8 +130,7 @@ static int etnaviv_gem_mmap_obj(struct etnaviv_gem_object *etnaviv_obj,
>>>> {
>>>> pgprot_t vm_page_prot;
>>>>
>>>> - vma->vm_flags &= ~VM_PFNMAP;
>>>> - vma->vm_flags |= VM_MIXEDMAP;
>>>> + vma->vm_flags |= VM_IO | VM_MIXEDMAP | VM_DONTEXPAND | VM_DONTDUMP;
>>>
>>> I don't fully understand why this change is needed and the commit log
>>> is silent about it. Excuse my ignorance, but can you please explain the
>>> reasoning behind this change?
>>
>> Sure, sorry for being brief.
>>
>> I worked on cleaning up the deprecated gem_prime_* callbacks in struct
>> drm_driver. These are supposed to be GEM object functions. The only
>> obsolete gem prime callback in drm_driver is gem_prime_mmap.
>
> Sorry, that's a misunderstanding. I see the justification for the patch
> as a whole. I was asking specifically about the hunk above my comment.
> Why are the vm_flags changed and how did you come up with this exact
> combination of flags?
I took the existing implementation and looked through it for the current
combination of flags.
Etnaviv calls etnaviv_gem_prime_mmap(), which in turn calls
drm_gem_mmap_obj(). [1] Because etnaviv doesn't have a gem object mmap
callback, drm_gem_mmap_obj() sets some default flags. [2] VM_PFNMAP
later gets cleared by the current code, so I left it out. And that's
where these flags come from.
I should add that I don't have the HW to test this change. If you can,
maybe give it a try.
Best regards
Thomas
[1]
https://elixir.bootlin.com/linux/v5.12/source/drivers/gpu/drm/etnaviv/etnaviv_gem_prime.c#L43
[2]
https://elixir.bootlin.com/linux/v5.12/source/drivers/gpu/drm/drm_gem.c#L1084
>
> Regards,
> Lucas
>
--
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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next prev parent reply other threads:[~2021-06-24 12:22 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-24 8:58 [PATCH] drm/etnaviv: Implement mmap as GEM object function Thomas Zimmermann
2021-06-24 9:11 ` Lucas Stach
2021-06-24 10:47 ` Thomas Zimmermann
2021-06-24 10:50 ` Lucas Stach
2021-06-24 12:22 ` Thomas Zimmermann [this message]
2021-07-05 11:47 ` Thomas Zimmermann
2021-07-06 16:34 ` Lucas Stach
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