[PATCH v2 00/10] Generic USB Display driver

[PATCH v2 00/10] Generic USB Display driver

[Noralf Trønnes]

Hi,

A while back I had the idea to turn a Raspberry Pi Zero into a $5
USB to HDMI/SDTV/DSI/DPI display adapter.

This series adds a USB host driver and a device/gadget driver to achieve
that.

The reason for calling it 'Generic' is so anyone can make a USB
display/adapter against this driver, all that's needed is to add a USB
vid:pid. I was hoping to have someone working on a microcontroller based
USB display by now, but unfortunately that has been delayed. It would
have been nice to have a microcontroller implementation to ensure that I
haven't made things unnecessary difficult to implement.

Performance
The one thing that decides how useful this all is, is how smooth an
experience it gives. My hope was that it should not be noticeably laggy
with ordinary office use on 1920x1080@RG16. I'm pleased to see that it's
also possible to watch youtube movies, although not in fullscreen.

Some of the main factors that affects performance:
- Display resolution
- Userspace providing damage reports (FB_DAMAGE_CLIPS or
  DRM_IOCTL_MODE_DIRTYFB)
- Color depth (DRM_CAP_DUMB_PREFERRED_DEPTH = 16 if RGB565)
- How well the frames compress (lz4)
- USB2 vs. USB3
- Gadget device memory bandwidth, CPU power for decompression
- (Big endian hosts will have to do byte swapping on the frames)

I've tested these:
- xorg-server on Pi4. This was nice and smooth since it uses
  DRM_IOCTL_MODE_DIRTYFB and honours DRM_CAP_DUMB_PREFERRED_DEPTH.
- Ubuntu 20.04 GNOME on x86. This was useable, but not so good for
  movies. GNOME doesn't look at DRM_CAP_DUMB_PREFERRED_DEPTH and doesn't
  set FB_DAMAGE_CLIPS on the pageflips.

I've made a short video to show what it looks like[1].

Tearing

Host side
Compression and transfer happens in an async worker.
There are 2 tearing cases here:
1. The framebuffer fits in the kmalloc'ed transfer buffer, max 4MB by
   default (KMALLOC_MAX_SIZE). This can give occasional tearing when
   userspace gets ahead of the worker.
2. The framebuffer doesn't fit in the transfer buffer, so the host
   splits the transfer. When showing a movie this will almost always give
   tearing between each part of the frame.
   Fix: The device can increase KMALLOC_MAX_SIZE by setting
   CONFIG_FORCE_MAX_ZONEORDER since it probably has a custom kernel
   anyways. The host distro can't/won't do that, so I have look for
   solution here.
The host side tearing is worse than the device side, because it lasts
longer.

Device side
Received updates are decompressed/copied into the framebuffer that's
being scanned out, so tearing is possible. Double buffering/page
flipping could be used for full frames, but well behaving userspace
doesn't send many of those, so very little impact. Double buffering on
all updates would require memcpy between buffers locally, hampering
performance. Maybe a Pi4 could get away with it, but a Pi Zero would
certainly not (memory bandwidth).

I've tested this series with usbip[2] by connecting 2 Pi4's over cabled
gigabit network. It worked fine.

One use case for these drivers is reusing old tablets and cell phones as
USB displays.

The Pi4 has two hdmi ports and I was asked if the driver supports that,
and I've concluded that it would be too much work to implement at this
point. It is possible to extend the protocol and implement it later.

I have used a Pi4 as the gadget device during development since it has
much better memory bandwith (4000 vs 200 MBps)[3] and CPU than the Pi
Zero. They both have the same gadget controller (dwc2).

Changes in this version:
- Drop drm_backlight_helper
- Use devm_drm_dev_alloc()
- Addressed Sam's comments


Noralf.

[1] https://youtu.be/AhGZWwUm8JU
[2] tools/usb/usbip/README
[3] https://magpi.raspberrypi.org/articles/raspberry-pi-specs-benchmarks


Noralf Trønnes (10):
  backlight: Add backlight_device_get_by_name()
  drm/client: Add drm_client_init_from_id()
  drm/client: Add drm_client_framebuffer_flush()
  drm/client: Add drm_client_modeset_check()
  drm/client: Add drm_client_modeset_disable()
  drm/client: Add a way to set modeset, properties and rotation
  drm/format-helper: Add drm_fb_swab()
  drm: Add Generic USB Display driver
  drm/gud: Add functionality for the USB gadget side
  usb: gadget: function: Add Generic USB Display support

 .../ABI/testing/configfs-usb-gadget-gud_drm   |   10 +
 MAINTAINERS                                   |   10 +
 drivers/gpu/drm/Kconfig                       |    2 +
 drivers/gpu/drm/Makefile                      |    1 +
 drivers/gpu/drm/drm_client.c                  |   81 +-
 drivers/gpu/drm/drm_client_modeset.c          |  192 ++-
 drivers/gpu/drm/drm_format_helper.c           |   61 +-
 drivers/gpu/drm/drm_mipi_dbi.c                |    2 +-
 drivers/gpu/drm/gud/Kconfig                   |   20 +
 drivers/gpu/drm/gud/Makefile                  |    5 +
 drivers/gpu/drm/gud/gud_drm_connector.c       |  724 ++++++++++
 drivers/gpu/drm/gud/gud_drm_drv.c             |  641 +++++++++
 drivers/gpu/drm/gud/gud_drm_gadget.c          | 1165 +++++++++++++++++
 drivers/gpu/drm/gud/gud_drm_internal.h        |   66 +
 drivers/gpu/drm/gud/gud_drm_pipe.c            |  423 ++++++
 drivers/usb/gadget/Kconfig                    |   12 +
 drivers/usb/gadget/function/Makefile          |    2 +
 drivers/usb/gadget/function/f_gud_drm.c       |  678 ++++++++++
 drivers/video/backlight/backlight.c           |   21 +
 include/drm/drm_client.h                      |   45 +-
 include/drm/drm_format_helper.h               |    4 +-
 include/drm/gud_drm.h                         |  377 ++++++
 include/linux/backlight.h                     |    1 +
 23 files changed, 4513 insertions(+), 30 deletions(-)
 create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-gud_drm
 create mode 100644 drivers/gpu/drm/gud/Kconfig
 create mode 100644 drivers/gpu/drm/gud/Makefile
 create mode 100644 drivers/gpu/drm/gud/gud_drm_connector.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_drv.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_gadget.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_internal.h
 create mode 100644 drivers/gpu/drm/gud/gud_drm_pipe.c
 create mode 100644 drivers/usb/gadget/function/f_gud_drm.c
 create mode 100644 include/drm/gud_drm.h

-- 
2.23.0

[PATCH v2 00/10] Generic USB Display driver

[Noralf Trønnes]

Hi,

A while back I had the idea to turn a Raspberry Pi Zero into a $5
USB to HDMI/SDTV/DSI/DPI display adapter.

This series adds a USB host driver and a device/gadget driver to achieve
that.

The reason for calling it 'Generic' is so anyone can make a USB
display/adapter against this driver, all that's needed is to add a USB
vid:pid. I was hoping to have someone working on a microcontroller based
USB display by now, but unfortunately that has been delayed. It would
have been nice to have a microcontroller implementation to ensure that I
haven't made things unnecessary difficult to implement.

Performance
The one thing that decides how useful this all is, is how smooth an
experience it gives. My hope was that it should not be noticeably laggy
with ordinary office use on 1920x1080@RG16. I'm pleased to see that it's
also possible to watch youtube movies, although not in fullscreen.

Some of the main factors that affects performance:
- Display resolution
- Userspace providing damage reports (FB_DAMAGE_CLIPS or
  DRM_IOCTL_MODE_DIRTYFB)
- Color depth (DRM_CAP_DUMB_PREFERRED_DEPTH = 16 if RGB565)
- How well the frames compress (lz4)
- USB2 vs. USB3
- Gadget device memory bandwidth, CPU power for decompression
- (Big endian hosts will have to do byte swapping on the frames)

I've tested these:
- xorg-server on Pi4. This was nice and smooth since it uses
  DRM_IOCTL_MODE_DIRTYFB and honours DRM_CAP_DUMB_PREFERRED_DEPTH.
- Ubuntu 20.04 GNOME on x86. This was useable, but not so good for
  movies. GNOME doesn't look at DRM_CAP_DUMB_PREFERRED_DEPTH and doesn't
  set FB_DAMAGE_CLIPS on the pageflips.

I've made a short video to show what it looks like[1].

Tearing

Host side
Compression and transfer happens in an async worker.
There are 2 tearing cases here:
1. The framebuffer fits in the kmalloc'ed transfer buffer, max 4MB by
   default (KMALLOC_MAX_SIZE). This can give occasional tearing when
   userspace gets ahead of the worker.
2. The framebuffer doesn't fit in the transfer buffer, so the host
   splits the transfer. When showing a movie this will almost always give
   tearing between each part of the frame.
   Fix: The device can increase KMALLOC_MAX_SIZE by setting
   CONFIG_FORCE_MAX_ZONEORDER since it probably has a custom kernel
   anyways. The host distro can't/won't do that, so I have look for
   solution here.
The host side tearing is worse than the device side, because it lasts
longer.

Device side
Received updates are decompressed/copied into the framebuffer that's
being scanned out, so tearing is possible. Double buffering/page
flipping could be used for full frames, but well behaving userspace
doesn't send many of those, so very little impact. Double buffering on
all updates would require memcpy between buffers locally, hampering
performance. Maybe a Pi4 could get away with it, but a Pi Zero would
certainly not (memory bandwidth).

I've tested this series with usbip[2] by connecting 2 Pi4's over cabled
gigabit network. It worked fine.

One use case for these drivers is reusing old tablets and cell phones as
USB displays.

The Pi4 has two hdmi ports and I was asked if the driver supports that,
and I've concluded that it would be too much work to implement at this
point. It is possible to extend the protocol and implement it later.

I have used a Pi4 as the gadget device during development since it has
much better memory bandwith (4000 vs 200 MBps)[3] and CPU than the Pi
Zero. They both have the same gadget controller (dwc2).

Changes in this version:
- Drop drm_backlight_helper
- Use devm_drm_dev_alloc()
- Addressed Sam's comments


Noralf.

[1] https://youtu.be/AhGZWwUm8JU
[2] tools/usb/usbip/README
[3] https://magpi.raspberrypi.org/articles/raspberry-pi-specs-benchmarks


Noralf Trønnes (10):
  backlight: Add backlight_device_get_by_name()
  drm/client: Add drm_client_init_from_id()
  drm/client: Add drm_client_framebuffer_flush()
  drm/client: Add drm_client_modeset_check()
  drm/client: Add drm_client_modeset_disable()
  drm/client: Add a way to set modeset, properties and rotation
  drm/format-helper: Add drm_fb_swab()
  drm: Add Generic USB Display driver
  drm/gud: Add functionality for the USB gadget side
  usb: gadget: function: Add Generic USB Display support

 .../ABI/testing/configfs-usb-gadget-gud_drm   |   10 +
 MAINTAINERS                                   |   10 +
 drivers/gpu/drm/Kconfig                       |    2 +
 drivers/gpu/drm/Makefile                      |    1 +
 drivers/gpu/drm/drm_client.c                  |   81 +-
 drivers/gpu/drm/drm_client_modeset.c          |  192 ++-
 drivers/gpu/drm/drm_format_helper.c           |   61 +-
 drivers/gpu/drm/drm_mipi_dbi.c                |    2 +-
 drivers/gpu/drm/gud/Kconfig                   |   20 +
 drivers/gpu/drm/gud/Makefile                  |    5 +
 drivers/gpu/drm/gud/gud_drm_connector.c       |  724 ++++++++++
 drivers/gpu/drm/gud/gud_drm_drv.c             |  641 +++++++++
 drivers/gpu/drm/gud/gud_drm_gadget.c          | 1165 +++++++++++++++++
 drivers/gpu/drm/gud/gud_drm_internal.h        |   66 +
 drivers/gpu/drm/gud/gud_drm_pipe.c            |  423 ++++++
 drivers/usb/gadget/Kconfig                    |   12 +
 drivers/usb/gadget/function/Makefile          |    2 +
 drivers/usb/gadget/function/f_gud_drm.c       |  678 ++++++++++
 drivers/video/backlight/backlight.c           |   21 +
 include/drm/drm_client.h                      |   45 +-
 include/drm/drm_format_helper.h               |    4 +-
 include/drm/gud_drm.h                         |  377 ++++++
 include/linux/backlight.h                     |    1 +
 23 files changed, 4513 insertions(+), 30 deletions(-)
 create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-gud_drm
 create mode 100644 drivers/gpu/drm/gud/Kconfig
 create mode 100644 drivers/gpu/drm/gud/Makefile
 create mode 100644 drivers/gpu/drm/gud/gud_drm_connector.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_drv.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_gadget.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_internal.h
 create mode 100644 drivers/gpu/drm/gud/gud_drm_pipe.c
 create mode 100644 drivers/usb/gadget/function/f_gud_drm.c
 create mode 100644 include/drm/gud_drm.h

-- 
2.23.0

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

[PATCH v2 01/10] backlight: Add backlight_device_get_by_name()

[Noralf Trønnes]

Add a way to lookup a backlight device based on its name.
Will be used by a USB display gadget getting the name from configfs.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/video/backlight/backlight.c | 21 +++++++++++++++++++++
 include/linux/backlight.h           |  1 +
 2 files changed, 22 insertions(+)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index cac3e35d7630..92d80aa0c0ef 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -432,6 +432,27 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
 }
 EXPORT_SYMBOL(backlight_device_get_by_type);
 
+/**
+ * backlight_device_get_by_name - Get backlight device by name
+ * @name: Device name
+ *
+ * This function looks up a backlight device by its name. It obtains a reference
+ * on the backlight device and it is the caller's responsibility to drop the
+ * reference by calling backlight_put().
+ *
+ * Returns:
+ * A pointer to the backlight device if found, otherwise NULL.
+ */
+struct backlight_device *backlight_device_get_by_name(const char *name)
+{
+	struct device *dev;
+
+	dev = class_find_device_by_name(backlight_class, name);
+
+	return dev ? to_backlight_device(dev) : NULL;
+}
+EXPORT_SYMBOL(backlight_device_get_by_name);
+
 /**
  * backlight_device_unregister - unregisters a backlight device object.
  * @bd: the backlight device object to be unregistered and freed.
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index c7d6b2e8c3b5..56e4580d4f55 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -190,6 +190,7 @@ extern void backlight_force_update(struct backlight_device *bd,
 extern int backlight_register_notifier(struct notifier_block *nb);
 extern int backlight_unregister_notifier(struct notifier_block *nb);
 extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
+struct backlight_device *backlight_device_get_by_name(const char *name);
 extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
 
 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
-- 
2.23.0

[PATCH v2 01/10] backlight: Add backlight_device_get_by_name()

[Noralf Trønnes]

Add a way to lookup a backlight device based on its name.
Will be used by a USB display gadget getting the name from configfs.

Cc: Lee Jones <lee.jones@linaro.org>
Cc: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Jingoo Han <jingoohan1@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/video/backlight/backlight.c | 21 +++++++++++++++++++++
 include/linux/backlight.h           |  1 +
 2 files changed, 22 insertions(+)

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index cac3e35d7630..92d80aa0c0ef 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -432,6 +432,27 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
 }
 EXPORT_SYMBOL(backlight_device_get_by_type);
 
+/**
+ * backlight_device_get_by_name - Get backlight device by name
+ * @name: Device name
+ *
+ * This function looks up a backlight device by its name. It obtains a reference
+ * on the backlight device and it is the caller's responsibility to drop the
+ * reference by calling backlight_put().
+ *
+ * Returns:
+ * A pointer to the backlight device if found, otherwise NULL.
+ */
+struct backlight_device *backlight_device_get_by_name(const char *name)
+{
+	struct device *dev;
+
+	dev = class_find_device_by_name(backlight_class, name);
+
+	return dev ? to_backlight_device(dev) : NULL;
+}
+EXPORT_SYMBOL(backlight_device_get_by_name);
+
 /**
  * backlight_device_unregister - unregisters a backlight device object.
  * @bd: the backlight device object to be unregistered and freed.
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index c7d6b2e8c3b5..56e4580d4f55 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -190,6 +190,7 @@ extern void backlight_force_update(struct backlight_device *bd,
 extern int backlight_register_notifier(struct notifier_block *nb);
 extern int backlight_unregister_notifier(struct notifier_block *nb);
 extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
+struct backlight_device *backlight_device_get_by_name(const char *name);
 extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
 
 #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
-- 
2.23.0

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

[PATCH v2 02/10] drm/client: Add drm_client_init_from_id()

[Noralf Trønnes]

drm_client_init_from_id() provides a way for clients to add a client based
on the minor. drm_client_register() is changed to return whether it was
registered or not depending on the unplugged status of the DRM device.
Its only caller drm_fbdev_generic_setup() runs inside probe() so it
doesn't have to check.

v2:
- Move drm_client_modeset_set() to a separate patch with added functions.
- Previous version had drm_client_init_from_id() call
  drm_client_register(). This put the client in a position where it could
  receive hotplugs during init in addition to akward error paths. Instead
  let drm_client_register() return status so clients can know if the DRM
  device is gone or not.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client.c | 48 +++++++++++++++++++++++++++++++++++-
 include/drm/drm_client.h     |  4 ++-
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 2a147d1c3a13..12787915db01 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -112,6 +112,40 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
 }
 EXPORT_SYMBOL(drm_client_init);
 
+/**
+ * drm_client_init_from_id - Initialise a DRM client
+ * @minor_id: DRM minor id
+ * @client: DRM client
+ * @name: Client name
+ * @funcs: DRM client functions (optional)
+ *
+ * This function looks up the drm_device using the minor id and initializes the client.
+ *
+ * See drm_client_init() and drm_client_register().
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_init_from_id(unsigned int minor_id, struct drm_client_dev *client,
+			    const char *name, const struct drm_client_funcs *funcs)
+{
+	struct drm_minor *minor;
+	int ret;
+
+	minor = drm_minor_acquire(minor_id);
+	if (IS_ERR(minor))
+		return PTR_ERR(minor);
+
+	mutex_lock(&minor->dev->clientlist_mutex);
+	ret = drm_client_init(minor->dev, client, name, funcs);
+	mutex_unlock(&minor->dev->clientlist_mutex);
+
+	drm_minor_release(minor);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_init_from_id);
+
 /**
  * drm_client_register - Register client
  * @client: DRM client
@@ -121,14 +155,26 @@ EXPORT_SYMBOL(drm_client_init);
  * drm_client_register() it is no longer permissible to call drm_client_release()
  * directly (outside the unregister callback), instead cleanup will happen
  * automatically on driver unload.
+ *
+ * Returns:
+ * True if the client has been registered, false if the DRM device has already
+ * been unregistered.
  */
-void drm_client_register(struct drm_client_dev *client)
+bool drm_client_register(struct drm_client_dev *client)
 {
 	struct drm_device *dev = client->dev;
+	int idx;
+
+	if (!drm_dev_enter(client->dev, &idx))
+		return false;
 
 	mutex_lock(&dev->clientlist_mutex);
 	list_add(&client->list, &dev->clientlist);
 	mutex_unlock(&dev->clientlist_mutex);
+
+	drm_dev_exit(idx);
+
+	return true;
 }
 EXPORT_SYMBOL(drm_client_register);
 
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 7402f852d3c4..96ebc7523aa0 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -109,8 +109,10 @@ struct drm_client_dev {
 
 int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
 		    const char *name, const struct drm_client_funcs *funcs);
+int drm_client_init_from_id(unsigned int minor_id, struct drm_client_dev *client,
+			    const char *name, const struct drm_client_funcs *funcs);
 void drm_client_release(struct drm_client_dev *client);
-void drm_client_register(struct drm_client_dev *client);
+bool drm_client_register(struct drm_client_dev *client);
 
 void drm_client_dev_unregister(struct drm_device *dev);
 void drm_client_dev_hotplug(struct drm_device *dev);
-- 
2.23.0

[PATCH v2 02/10] drm/client: Add drm_client_init_from_id()

[Noralf Trønnes]

drm_client_init_from_id() provides a way for clients to add a client based
on the minor. drm_client_register() is changed to return whether it was
registered or not depending on the unplugged status of the DRM device.
Its only caller drm_fbdev_generic_setup() runs inside probe() so it
doesn't have to check.

v2:
- Move drm_client_modeset_set() to a separate patch with added functions.
- Previous version had drm_client_init_from_id() call
  drm_client_register(). This put the client in a position where it could
  receive hotplugs during init in addition to akward error paths. Instead
  let drm_client_register() return status so clients can know if the DRM
  device is gone or not.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client.c | 48 +++++++++++++++++++++++++++++++++++-
 include/drm/drm_client.h     |  4 ++-
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 2a147d1c3a13..12787915db01 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -112,6 +112,40 @@ int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
 }
 EXPORT_SYMBOL(drm_client_init);
 
+/**
+ * drm_client_init_from_id - Initialise a DRM client
+ * @minor_id: DRM minor id
+ * @client: DRM client
+ * @name: Client name
+ * @funcs: DRM client functions (optional)
+ *
+ * This function looks up the drm_device using the minor id and initializes the client.
+ *
+ * See drm_client_init() and drm_client_register().
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_init_from_id(unsigned int minor_id, struct drm_client_dev *client,
+			    const char *name, const struct drm_client_funcs *funcs)
+{
+	struct drm_minor *minor;
+	int ret;
+
+	minor = drm_minor_acquire(minor_id);
+	if (IS_ERR(minor))
+		return PTR_ERR(minor);
+
+	mutex_lock(&minor->dev->clientlist_mutex);
+	ret = drm_client_init(minor->dev, client, name, funcs);
+	mutex_unlock(&minor->dev->clientlist_mutex);
+
+	drm_minor_release(minor);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_init_from_id);
+
 /**
  * drm_client_register - Register client
  * @client: DRM client
@@ -121,14 +155,26 @@ EXPORT_SYMBOL(drm_client_init);
  * drm_client_register() it is no longer permissible to call drm_client_release()
  * directly (outside the unregister callback), instead cleanup will happen
  * automatically on driver unload.
+ *
+ * Returns:
+ * True if the client has been registered, false if the DRM device has already
+ * been unregistered.
  */
-void drm_client_register(struct drm_client_dev *client)
+bool drm_client_register(struct drm_client_dev *client)
 {
 	struct drm_device *dev = client->dev;
+	int idx;
+
+	if (!drm_dev_enter(client->dev, &idx))
+		return false;
 
 	mutex_lock(&dev->clientlist_mutex);
 	list_add(&client->list, &dev->clientlist);
 	mutex_unlock(&dev->clientlist_mutex);
+
+	drm_dev_exit(idx);
+
+	return true;
 }
 EXPORT_SYMBOL(drm_client_register);
 
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 7402f852d3c4..96ebc7523aa0 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -109,8 +109,10 @@ struct drm_client_dev {
 
 int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
 		    const char *name, const struct drm_client_funcs *funcs);
+int drm_client_init_from_id(unsigned int minor_id, struct drm_client_dev *client,
+			    const char *name, const struct drm_client_funcs *funcs);
 void drm_client_release(struct drm_client_dev *client);
-void drm_client_register(struct drm_client_dev *client);
+bool drm_client_register(struct drm_client_dev *client);
 
 void drm_client_dev_unregister(struct drm_device *dev);
 void drm_client_dev_hotplug(struct drm_device *dev);
-- 
2.23.0

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[PATCH v2 03/10] drm/client: Add drm_client_framebuffer_flush()

[Noralf Trønnes]

Some drivers need explicit flushing of buffer changes, add a function
that does that.

v2:
- Put all clip rect stuff inside if statement (Sam)

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client.c | 33 +++++++++++++++++++++++++++++++++
 include/drm/drm_client.h     |  1 +
 2 files changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 12787915db01..827ee6422dd2 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -483,6 +483,39 @@ void drm_client_framebuffer_delete(struct drm_client_buffer *buffer)
 }
 EXPORT_SYMBOL(drm_client_framebuffer_delete);
 
+/**
+ * drm_client_framebuffer_flush - Manually flush client framebuffer
+ * @buffer: DRM client buffer (can be NULL)
+ * @rect: Damage rectangle (if NULL flushes all)
+ *
+ * This calls &drm_framebuffer_funcs->dirty (if present) to flush buffer changes
+ * for drivers that need it.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
+{
+	if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)
+		return 0;
+
+	if (rect) {
+		struct drm_clip_rect clip = {
+			.x1 = rect->x1,
+			.y1 = rect->y1,
+			.x2 = rect->x2,
+			.y2 = rect->y2,
+		};
+
+		return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
+						0, 0, &clip, 1);
+	}
+
+	return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
+					0, 0, NULL, 0);
+}
+EXPORT_SYMBOL(drm_client_framebuffer_flush);
+
 #ifdef CONFIG_DEBUG_FS
 static int drm_client_debugfs_internal_clients(struct seq_file *m, void *data)
 {
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 96ebc7523aa0..9737dd7b147f 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -156,6 +156,7 @@ struct drm_client_buffer {
 struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
+int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect);
 void *drm_client_buffer_vmap(struct drm_client_buffer *buffer);
 void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);
 
-- 
2.23.0

[PATCH v2 03/10] drm/client: Add drm_client_framebuffer_flush()

[Noralf Trønnes]

Some drivers need explicit flushing of buffer changes, add a function
that does that.

v2:
- Put all clip rect stuff inside if statement (Sam)

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client.c | 33 +++++++++++++++++++++++++++++++++
 include/drm/drm_client.h     |  1 +
 2 files changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index 12787915db01..827ee6422dd2 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -483,6 +483,39 @@ void drm_client_framebuffer_delete(struct drm_client_buffer *buffer)
 }
 EXPORT_SYMBOL(drm_client_framebuffer_delete);
 
+/**
+ * drm_client_framebuffer_flush - Manually flush client framebuffer
+ * @buffer: DRM client buffer (can be NULL)
+ * @rect: Damage rectangle (if NULL flushes all)
+ *
+ * This calls &drm_framebuffer_funcs->dirty (if present) to flush buffer changes
+ * for drivers that need it.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
+{
+	if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)
+		return 0;
+
+	if (rect) {
+		struct drm_clip_rect clip = {
+			.x1 = rect->x1,
+			.y1 = rect->y1,
+			.x2 = rect->x2,
+			.y2 = rect->y2,
+		};
+
+		return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
+						0, 0, &clip, 1);
+	}
+
+	return buffer->fb->funcs->dirty(buffer->fb, buffer->client->file,
+					0, 0, NULL, 0);
+}
+EXPORT_SYMBOL(drm_client_framebuffer_flush);
+
 #ifdef CONFIG_DEBUG_FS
 static int drm_client_debugfs_internal_clients(struct seq_file *m, void *data)
 {
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 96ebc7523aa0..9737dd7b147f 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -156,6 +156,7 @@ struct drm_client_buffer {
 struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
+int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect);
 void *drm_client_buffer_vmap(struct drm_client_buffer *buffer);
 void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);
 
-- 
2.23.0

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[PATCH v2 04/10] drm/client: Add drm_client_modeset_check()

[Noralf Trønnes]

Add a way for client to check the configuration before comitting.

v2:
- Fix docs (Sam)

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client_modeset.c | 35 ++++++++++++++++++++++++----
 include/drm/drm_client.h             |  1 +
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index 7443114bd713..9d1ab69dd8d0 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -966,7 +966,7 @@ bool drm_client_rotation(struct drm_mode_set *modeset, unsigned int *rotation)
 }
 EXPORT_SYMBOL(drm_client_rotation);
 
-static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool active)
+static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool active, bool check)
 {
 	struct drm_device *dev = client->dev;
 	struct drm_plane *plane;
@@ -1033,7 +1033,10 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
 		}
 	}
 
-	ret = drm_atomic_commit(state);
+	if (check)
+		ret = drm_atomic_check_only(state);
+	else
+		ret = drm_atomic_commit(state);
 
 out_state:
 	if (ret == -EDEADLK)
@@ -1094,6 +1097,30 @@ static int drm_client_modeset_commit_legacy(struct drm_client_dev *client)
 	return ret;
 }
 
+/**
+ * drm_client_modeset_check() - Check modeset configuration
+ * @client: DRM client
+ *
+ * Check modeset configuration.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_check(struct drm_client_dev *client)
+{
+	int ret;
+
+	if (!drm_drv_uses_atomic_modeset(client->dev))
+		return 0;
+
+	mutex_lock(&client->modeset_mutex);
+	ret = drm_client_modeset_commit_atomic(client, true, true);
+	mutex_unlock(&client->modeset_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_modeset_check);
+
 /**
  * drm_client_modeset_commit_locked() - Force commit CRTC configuration
  * @client: DRM client
@@ -1112,7 +1139,7 @@ int drm_client_modeset_commit_locked(struct drm_client_dev *client)
 
 	mutex_lock(&client->modeset_mutex);
 	if (drm_drv_uses_atomic_modeset(dev))
-		ret = drm_client_modeset_commit_atomic(client, true);
+		ret = drm_client_modeset_commit_atomic(client, true, false);
 	else
 		ret = drm_client_modeset_commit_legacy(client);
 	mutex_unlock(&client->modeset_mutex);
@@ -1188,7 +1215,7 @@ int drm_client_modeset_dpms(struct drm_client_dev *client, int mode)
 
 	mutex_lock(&client->modeset_mutex);
 	if (drm_drv_uses_atomic_modeset(dev))
-		ret = drm_client_modeset_commit_atomic(client, mode == DRM_MODE_DPMS_ON);
+		ret = drm_client_modeset_commit_atomic(client, mode == DRM_MODE_DPMS_ON, false);
 	else
 		drm_client_modeset_dpms_legacy(client, mode);
 	mutex_unlock(&client->modeset_mutex);
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 9737dd7b147f..76704f48fc46 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -164,6 +164,7 @@ int drm_client_modeset_create(struct drm_client_dev *client);
 void drm_client_modeset_free(struct drm_client_dev *client);
 int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, unsigned int height);
 bool drm_client_rotation(struct drm_mode_set *modeset, unsigned int *rotation);
+int drm_client_modeset_check(struct drm_client_dev *client);
 int drm_client_modeset_commit_locked(struct drm_client_dev *client);
 int drm_client_modeset_commit(struct drm_client_dev *client);
 int drm_client_modeset_dpms(struct drm_client_dev *client, int mode);
-- 
2.23.0

[PATCH v2 04/10] drm/client: Add drm_client_modeset_check()

[Noralf Trønnes]

Add a way for client to check the configuration before comitting.

v2:
- Fix docs (Sam)

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client_modeset.c | 35 ++++++++++++++++++++++++----
 include/drm/drm_client.h             |  1 +
 2 files changed, 32 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index 7443114bd713..9d1ab69dd8d0 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -966,7 +966,7 @@ bool drm_client_rotation(struct drm_mode_set *modeset, unsigned int *rotation)
 }
 EXPORT_SYMBOL(drm_client_rotation);
 
-static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool active)
+static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool active, bool check)
 {
 	struct drm_device *dev = client->dev;
 	struct drm_plane *plane;
@@ -1033,7 +1033,10 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
 		}
 	}
 
-	ret = drm_atomic_commit(state);
+	if (check)
+		ret = drm_atomic_check_only(state);
+	else
+		ret = drm_atomic_commit(state);
 
 out_state:
 	if (ret == -EDEADLK)
@@ -1094,6 +1097,30 @@ static int drm_client_modeset_commit_legacy(struct drm_client_dev *client)
 	return ret;
 }
 
+/**
+ * drm_client_modeset_check() - Check modeset configuration
+ * @client: DRM client
+ *
+ * Check modeset configuration.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_check(struct drm_client_dev *client)
+{
+	int ret;
+
+	if (!drm_drv_uses_atomic_modeset(client->dev))
+		return 0;
+
+	mutex_lock(&client->modeset_mutex);
+	ret = drm_client_modeset_commit_atomic(client, true, true);
+	mutex_unlock(&client->modeset_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_modeset_check);
+
 /**
  * drm_client_modeset_commit_locked() - Force commit CRTC configuration
  * @client: DRM client
@@ -1112,7 +1139,7 @@ int drm_client_modeset_commit_locked(struct drm_client_dev *client)
 
 	mutex_lock(&client->modeset_mutex);
 	if (drm_drv_uses_atomic_modeset(dev))
-		ret = drm_client_modeset_commit_atomic(client, true);
+		ret = drm_client_modeset_commit_atomic(client, true, false);
 	else
 		ret = drm_client_modeset_commit_legacy(client);
 	mutex_unlock(&client->modeset_mutex);
@@ -1188,7 +1215,7 @@ int drm_client_modeset_dpms(struct drm_client_dev *client, int mode)
 
 	mutex_lock(&client->modeset_mutex);
 	if (drm_drv_uses_atomic_modeset(dev))
-		ret = drm_client_modeset_commit_atomic(client, mode == DRM_MODE_DPMS_ON);
+		ret = drm_client_modeset_commit_atomic(client, mode == DRM_MODE_DPMS_ON, false);
 	else
 		drm_client_modeset_dpms_legacy(client, mode);
 	mutex_unlock(&client->modeset_mutex);
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 9737dd7b147f..76704f48fc46 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -164,6 +164,7 @@ int drm_client_modeset_create(struct drm_client_dev *client);
 void drm_client_modeset_free(struct drm_client_dev *client);
 int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, unsigned int height);
 bool drm_client_rotation(struct drm_mode_set *modeset, unsigned int *rotation);
+int drm_client_modeset_check(struct drm_client_dev *client);
 int drm_client_modeset_commit_locked(struct drm_client_dev *client);
 int drm_client_modeset_commit(struct drm_client_dev *client);
 int drm_client_modeset_dpms(struct drm_client_dev *client, int mode);
-- 
2.23.0

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[PATCH v2 05/10] drm/client: Add drm_client_modeset_disable()

[Noralf Trønnes]

Add a way for clients to disable all outputs.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client_modeset.c | 20 ++++++++++++++++++++
 include/drm/drm_client.h             |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index 9d1ab69dd8d0..b96183fadd4c 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -1225,3 +1225,23 @@ int drm_client_modeset_dpms(struct drm_client_dev *client, int mode)
 	return ret;
 }
 EXPORT_SYMBOL(drm_client_modeset_dpms);
+
+/**
+ * drm_client_modeset_disable() - Disable all outputs
+ * @client: DRM client
+ *
+ * This function disables all outputs by first clearing the modeset array and
+ * then committing the empty modesets.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_disable(struct drm_client_dev *client)
+{
+	mutex_lock(&client->modeset_mutex);
+	drm_client_modeset_release(client);
+	mutex_unlock(&client->modeset_mutex);
+
+	return drm_client_modeset_commit(client);
+}
+EXPORT_SYMBOL(drm_client_modeset_disable);
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 76704f48fc46..498089b647da 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -168,6 +168,7 @@ int drm_client_modeset_check(struct drm_client_dev *client);
 int drm_client_modeset_commit_locked(struct drm_client_dev *client);
 int drm_client_modeset_commit(struct drm_client_dev *client);
 int drm_client_modeset_dpms(struct drm_client_dev *client, int mode);
+int drm_client_modeset_disable(struct drm_client_dev *client);
 
 /**
  * drm_client_for_each_modeset() - Iterate over client modesets
-- 
2.23.0

[PATCH v2 05/10] drm/client: Add drm_client_modeset_disable()

[Noralf Trønnes]

Add a way for clients to disable all outputs.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client_modeset.c | 20 ++++++++++++++++++++
 include/drm/drm_client.h             |  1 +
 2 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index 9d1ab69dd8d0..b96183fadd4c 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -1225,3 +1225,23 @@ int drm_client_modeset_dpms(struct drm_client_dev *client, int mode)
 	return ret;
 }
 EXPORT_SYMBOL(drm_client_modeset_dpms);
+
+/**
+ * drm_client_modeset_disable() - Disable all outputs
+ * @client: DRM client
+ *
+ * This function disables all outputs by first clearing the modeset array and
+ * then committing the empty modesets.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_disable(struct drm_client_dev *client)
+{
+	mutex_lock(&client->modeset_mutex);
+	drm_client_modeset_release(client);
+	mutex_unlock(&client->modeset_mutex);
+
+	return drm_client_modeset_commit(client);
+}
+EXPORT_SYMBOL(drm_client_modeset_disable);
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 76704f48fc46..498089b647da 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -168,6 +168,7 @@ int drm_client_modeset_check(struct drm_client_dev *client);
 int drm_client_modeset_commit_locked(struct drm_client_dev *client);
 int drm_client_modeset_commit(struct drm_client_dev *client);
 int drm_client_modeset_dpms(struct drm_client_dev *client, int mode);
+int drm_client_modeset_disable(struct drm_client_dev *client);
 
 /**
  * drm_client_for_each_modeset() - Iterate over client modesets
-- 
2.23.0

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[PATCH v2 06/10] drm/client: Add a way to set modeset, properties and rotation

[Noralf Trønnes]

This adds functions for clients that need more control over the
configuration than what's setup by drm_client_modeset_probe().
Connector, fb and display mode can be set using drm_client_modeset_set().
Plane rotation can be set using drm_client_modeset_set_rotation() and
other properties using drm_client_modeset_set_property(). Property
setting is only implemented for atomic drivers.

v2:
- drm_client_modeset_set(): Remove undocumented functionality to clear
  modesets. A disable function takes care of that need now.
- drm_client_modeset_set_property(): Return -EOPNOTSUPP if driver is not
  atomic (Sam)

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client_modeset.c | 137 +++++++++++++++++++++++++++
 include/drm/drm_client.h             |  38 +++++++-
 2 files changed, 174 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index b96183fadd4c..b22cc63d8da4 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -83,6 +83,10 @@ static void drm_client_modeset_release(struct drm_client_dev *client)
 		}
 		modeset->num_connectors = 0;
 	}
+
+	kfree(client->properties);
+	client->properties = NULL;
+	client->num_properties = 0;
 }
 
 void drm_client_modeset_free(struct drm_client_dev *client)
@@ -879,6 +883,130 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
 }
 EXPORT_SYMBOL(drm_client_modeset_probe);
 
+/**
+ * drm_client_modeset_set() - Set modeset configuration
+ * @client: DRM client
+ * @connector: Connector
+ * @mode: Display mode
+ * @fb: Framebuffer
+ *
+ * This function releases any current modeset info, including properties, and
+ * sets the new modeset in the client's modeset array.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_set(struct drm_client_dev *client, struct drm_connector *connector,
+			   struct drm_display_mode *mode, struct drm_framebuffer *fb)
+{
+	struct drm_mode_set *modeset;
+	int ret = -ENOENT;
+
+	mutex_lock(&client->modeset_mutex);
+
+	drm_client_modeset_release(client);
+
+	drm_client_for_each_modeset(modeset, client) {
+		if (!connector_has_possible_crtc(connector, modeset->crtc))
+			continue;
+
+		modeset->mode = drm_mode_duplicate(client->dev, mode);
+		if (!modeset->mode) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		drm_mode_set_crtcinfo(modeset->mode, CRTC_INTERLACE_HALVE_V);
+
+		drm_connector_get(connector);
+		modeset->connectors[modeset->num_connectors++] = connector;
+
+		modeset->fb = fb;
+		ret = 0;
+		break;
+	}
+
+	mutex_unlock(&client->modeset_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_modeset_set);
+
+/**
+ * drm_client_modeset_set_property() - Set a property on the current configuration
+ * @client: DRM client
+ * @obj: DRM Mode Object
+ * @prop: DRM Property
+ * @value: Property value
+ *
+ * Note: Currently only implemented for atomic drivers.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_set_property(struct drm_client_dev *client, struct drm_mode_object *obj,
+				    struct drm_property *prop, u64 value)
+{
+	struct drm_client_property *properties;
+	int ret = 0;
+
+	if (!prop)
+		return -EINVAL;
+
+	if (!drm_drv_uses_atomic_modeset(client->dev))
+		return -EOPNOTSUPP;
+
+	mutex_lock(&client->modeset_mutex);
+
+	properties = krealloc(client->properties,
+			      (client->num_properties + 1) * sizeof(*properties), GFP_KERNEL);
+	if (!properties) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	properties[client->num_properties].obj = obj;
+	properties[client->num_properties].prop = prop;
+	properties[client->num_properties].value = value;
+	client->properties = properties;
+	client->num_properties++;
+unlock:
+	mutex_unlock(&client->modeset_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_modeset_set_property);
+
+/**
+ * drm_client_modeset_set_rotation() - Set rotation on the current configuration
+ * @client: DRM client
+ * @value: Rotation value
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_set_rotation(struct drm_client_dev *client, u64 value)
+{
+	struct drm_plane *plane = NULL;
+	struct drm_mode_set *modeset;
+
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(modeset, client) {
+		if (modeset->mode) {
+			plane = modeset->crtc->primary;
+			break;
+		}
+	}
+	mutex_unlock(&client->modeset_mutex);
+
+	if (!plane)
+		return -ENOENT;
+
+	return drm_client_modeset_set_property(client, &plane->base,
+					       plane->rotation_property, value);
+}
+EXPORT_SYMBOL(drm_client_modeset_set_rotation);
+
 /**
  * drm_client_rotation() - Check the initial rotation value
  * @modeset: DRM modeset
@@ -973,6 +1101,7 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
 	struct drm_atomic_state *state;
 	struct drm_modeset_acquire_ctx ctx;
 	struct drm_mode_set *mode_set;
+	unsigned int i;
 	int ret;
 
 	drm_modeset_acquire_init(&ctx, 0);
@@ -1033,6 +1162,14 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
 		}
 	}
 
+	for (i = 0; i < client->num_properties; i++) {
+		struct drm_client_property *prop = &client->properties[i];
+
+		ret = drm_atomic_set_property(state, NULL, prop->obj, prop->prop, prop->value);
+		if (ret)
+			goto out_state;
+	}
+
 	if (check)
 		ret = drm_atomic_check_only(state);
 	else
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 498089b647da..bdcdc30519e6 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -16,6 +16,7 @@ struct drm_file;
 struct drm_framebuffer;
 struct drm_gem_object;
 struct drm_minor;
+struct drm_property;
 struct module;
 
 /**
@@ -64,6 +65,26 @@ struct drm_client_funcs {
 	int (*hotplug)(struct drm_client_dev *client);
 };
 
+/**
+ * struct drm_client_property - DRM client property
+ */
+struct drm_client_property {
+	/**
+	 * @obj: DRM Mode Object to which the property belongs.
+	 */
+	struct drm_mode_object *obj;
+
+	/**
+	 * @prop: DRM Property.
+	 */
+	struct drm_property *prop;
+
+	/**
+	 * @value: Property value.
+	 */
+	u64 value;
+};
+
 /**
  * struct drm_client_dev - DRM client instance
  */
@@ -97,7 +118,7 @@ struct drm_client_dev {
 	struct drm_file *file;
 
 	/**
-	 * @modeset_mutex: Protects @modesets.
+	 * @modeset_mutex: Protects @modesets and @properties.
 	 */
 	struct mutex modeset_mutex;
 
@@ -105,6 +126,16 @@ struct drm_client_dev {
 	 * @modesets: CRTC configurations
 	 */
 	struct drm_mode_set *modesets;
+
+	/**
+	 * @properties: DRM properties attached to the configuration.
+	 */
+	struct drm_client_property *properties;
+
+	/**
+	 * @num_properties: Number of attached properties.
+	 */
+	unsigned int num_properties;
 };
 
 int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
@@ -163,6 +194,11 @@ void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);
 int drm_client_modeset_create(struct drm_client_dev *client);
 void drm_client_modeset_free(struct drm_client_dev *client);
 int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, unsigned int height);
+int drm_client_modeset_set(struct drm_client_dev *client, struct drm_connector *connector,
+			   struct drm_display_mode *mode, struct drm_framebuffer *fb);
+int drm_client_modeset_set_property(struct drm_client_dev *client, struct drm_mode_object *obj,
+				    struct drm_property *prop, u64 value);
+int drm_client_modeset_set_rotation(struct drm_client_dev *client, u64 value);
 bool drm_client_rotation(struct drm_mode_set *modeset, unsigned int *rotation);
 int drm_client_modeset_check(struct drm_client_dev *client);
 int drm_client_modeset_commit_locked(struct drm_client_dev *client);
-- 
2.23.0

[PATCH v2 06/10] drm/client: Add a way to set modeset, properties and rotation

[Noralf Trønnes]

This adds functions for clients that need more control over the
configuration than what's setup by drm_client_modeset_probe().
Connector, fb and display mode can be set using drm_client_modeset_set().
Plane rotation can be set using drm_client_modeset_set_rotation() and
other properties using drm_client_modeset_set_property(). Property
setting is only implemented for atomic drivers.

v2:
- drm_client_modeset_set(): Remove undocumented functionality to clear
  modesets. A disable function takes care of that need now.
- drm_client_modeset_set_property(): Return -EOPNOTSUPP if driver is not
  atomic (Sam)

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_client_modeset.c | 137 +++++++++++++++++++++++++++
 include/drm/drm_client.h             |  38 +++++++-
 2 files changed, 174 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c
index b96183fadd4c..b22cc63d8da4 100644
--- a/drivers/gpu/drm/drm_client_modeset.c
+++ b/drivers/gpu/drm/drm_client_modeset.c
@@ -83,6 +83,10 @@ static void drm_client_modeset_release(struct drm_client_dev *client)
 		}
 		modeset->num_connectors = 0;
 	}
+
+	kfree(client->properties);
+	client->properties = NULL;
+	client->num_properties = 0;
 }
 
 void drm_client_modeset_free(struct drm_client_dev *client)
@@ -879,6 +883,130 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width,
 }
 EXPORT_SYMBOL(drm_client_modeset_probe);
 
+/**
+ * drm_client_modeset_set() - Set modeset configuration
+ * @client: DRM client
+ * @connector: Connector
+ * @mode: Display mode
+ * @fb: Framebuffer
+ *
+ * This function releases any current modeset info, including properties, and
+ * sets the new modeset in the client's modeset array.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_set(struct drm_client_dev *client, struct drm_connector *connector,
+			   struct drm_display_mode *mode, struct drm_framebuffer *fb)
+{
+	struct drm_mode_set *modeset;
+	int ret = -ENOENT;
+
+	mutex_lock(&client->modeset_mutex);
+
+	drm_client_modeset_release(client);
+
+	drm_client_for_each_modeset(modeset, client) {
+		if (!connector_has_possible_crtc(connector, modeset->crtc))
+			continue;
+
+		modeset->mode = drm_mode_duplicate(client->dev, mode);
+		if (!modeset->mode) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		drm_mode_set_crtcinfo(modeset->mode, CRTC_INTERLACE_HALVE_V);
+
+		drm_connector_get(connector);
+		modeset->connectors[modeset->num_connectors++] = connector;
+
+		modeset->fb = fb;
+		ret = 0;
+		break;
+	}
+
+	mutex_unlock(&client->modeset_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_modeset_set);
+
+/**
+ * drm_client_modeset_set_property() - Set a property on the current configuration
+ * @client: DRM client
+ * @obj: DRM Mode Object
+ * @prop: DRM Property
+ * @value: Property value
+ *
+ * Note: Currently only implemented for atomic drivers.
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_set_property(struct drm_client_dev *client, struct drm_mode_object *obj,
+				    struct drm_property *prop, u64 value)
+{
+	struct drm_client_property *properties;
+	int ret = 0;
+
+	if (!prop)
+		return -EINVAL;
+
+	if (!drm_drv_uses_atomic_modeset(client->dev))
+		return -EOPNOTSUPP;
+
+	mutex_lock(&client->modeset_mutex);
+
+	properties = krealloc(client->properties,
+			      (client->num_properties + 1) * sizeof(*properties), GFP_KERNEL);
+	if (!properties) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	properties[client->num_properties].obj = obj;
+	properties[client->num_properties].prop = prop;
+	properties[client->num_properties].value = value;
+	client->properties = properties;
+	client->num_properties++;
+unlock:
+	mutex_unlock(&client->modeset_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_client_modeset_set_property);
+
+/**
+ * drm_client_modeset_set_rotation() - Set rotation on the current configuration
+ * @client: DRM client
+ * @value: Rotation value
+ *
+ * Returns:
+ * Zero on success or negative error code on failure.
+ */
+int drm_client_modeset_set_rotation(struct drm_client_dev *client, u64 value)
+{
+	struct drm_plane *plane = NULL;
+	struct drm_mode_set *modeset;
+
+	mutex_lock(&client->modeset_mutex);
+	drm_client_for_each_modeset(modeset, client) {
+		if (modeset->mode) {
+			plane = modeset->crtc->primary;
+			break;
+		}
+	}
+	mutex_unlock(&client->modeset_mutex);
+
+	if (!plane)
+		return -ENOENT;
+
+	return drm_client_modeset_set_property(client, &plane->base,
+					       plane->rotation_property, value);
+}
+EXPORT_SYMBOL(drm_client_modeset_set_rotation);
+
 /**
  * drm_client_rotation() - Check the initial rotation value
  * @modeset: DRM modeset
@@ -973,6 +1101,7 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
 	struct drm_atomic_state *state;
 	struct drm_modeset_acquire_ctx ctx;
 	struct drm_mode_set *mode_set;
+	unsigned int i;
 	int ret;
 
 	drm_modeset_acquire_init(&ctx, 0);
@@ -1033,6 +1162,14 @@ static int drm_client_modeset_commit_atomic(struct drm_client_dev *client, bool
 		}
 	}
 
+	for (i = 0; i < client->num_properties; i++) {
+		struct drm_client_property *prop = &client->properties[i];
+
+		ret = drm_atomic_set_property(state, NULL, prop->obj, prop->prop, prop->value);
+		if (ret)
+			goto out_state;
+	}
+
 	if (check)
 		ret = drm_atomic_check_only(state);
 	else
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index 498089b647da..bdcdc30519e6 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -16,6 +16,7 @@ struct drm_file;
 struct drm_framebuffer;
 struct drm_gem_object;
 struct drm_minor;
+struct drm_property;
 struct module;
 
 /**
@@ -64,6 +65,26 @@ struct drm_client_funcs {
 	int (*hotplug)(struct drm_client_dev *client);
 };
 
+/**
+ * struct drm_client_property - DRM client property
+ */
+struct drm_client_property {
+	/**
+	 * @obj: DRM Mode Object to which the property belongs.
+	 */
+	struct drm_mode_object *obj;
+
+	/**
+	 * @prop: DRM Property.
+	 */
+	struct drm_property *prop;
+
+	/**
+	 * @value: Property value.
+	 */
+	u64 value;
+};
+
 /**
  * struct drm_client_dev - DRM client instance
  */
@@ -97,7 +118,7 @@ struct drm_client_dev {
 	struct drm_file *file;
 
 	/**
-	 * @modeset_mutex: Protects @modesets.
+	 * @modeset_mutex: Protects @modesets and @properties.
 	 */
 	struct mutex modeset_mutex;
 
@@ -105,6 +126,16 @@ struct drm_client_dev {
 	 * @modesets: CRTC configurations
 	 */
 	struct drm_mode_set *modesets;
+
+	/**
+	 * @properties: DRM properties attached to the configuration.
+	 */
+	struct drm_client_property *properties;
+
+	/**
+	 * @num_properties: Number of attached properties.
+	 */
+	unsigned int num_properties;
 };
 
 int drm_client_init(struct drm_device *dev, struct drm_client_dev *client,
@@ -163,6 +194,11 @@ void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);
 int drm_client_modeset_create(struct drm_client_dev *client);
 void drm_client_modeset_free(struct drm_client_dev *client);
 int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, unsigned int height);
+int drm_client_modeset_set(struct drm_client_dev *client, struct drm_connector *connector,
+			   struct drm_display_mode *mode, struct drm_framebuffer *fb);
+int drm_client_modeset_set_property(struct drm_client_dev *client, struct drm_mode_object *obj,
+				    struct drm_property *prop, u64 value);
+int drm_client_modeset_set_rotation(struct drm_client_dev *client, u64 value);
 bool drm_client_rotation(struct drm_mode_set *modeset, unsigned int *rotation);
 int drm_client_modeset_check(struct drm_client_dev *client);
 int drm_client_modeset_commit_locked(struct drm_client_dev *client);
-- 
2.23.0

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

[PATCH v2 07/10] drm/format-helper: Add drm_fb_swab()

[Noralf Trønnes]

This replaces drm_fb_swab16() with drm_fb_swab() supporting 16 and 32-bit.
Also make pixel line caching optional.

v2:
- Bail out on cpp != 2 && 4 (Sam)

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_format_helper.c | 61 +++++++++++++++++++----------
 drivers/gpu/drm/drm_mipi_dbi.c      |  2 +-
 include/drm/drm_format_helper.h     |  4 +-
 3 files changed, 44 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 0897cb9aeaff..07c9999f1527 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -79,39 +79,60 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
 EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
 
 /**
- * drm_fb_swab16 - Swap bytes into clip buffer
- * @dst: RGB565 destination buffer
- * @vaddr: RGB565 source buffer
+ * drm_fb_swab - Swap bytes into clip buffer
+ * @dst: Destination buffer
+ * @src: Source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
+ * @cached: Source buffer is mapped cached (eg. not write-combined)
+ *
+ * If @cached is false a temporary buffer is used to cache one pixel line at a
+ * time to speed up slow uncached reads.
+ *
+ * This function does not apply clipping on dst, i.e. the destination
+ * is a small buffer containing the clip rect only.
  */
-void drm_fb_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
-		   struct drm_rect *clip)
+void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
+		 struct drm_rect *clip, bool cached)
 {
-	size_t len = (clip->x2 - clip->x1) * sizeof(u16);
+	u8 cpp = fb->format->cpp[0];
+	size_t len = drm_rect_width(clip) * cpp;
+	u16 *src16, *dst16 = dst;
+	u32 *src32, *dst32 = dst;
 	unsigned int x, y;
-	u16 *src, *buf;
+	void *buf = NULL;
 
-	/*
-	 * The cma memory is write-combined so reads are uncached.
-	 * Speed up by fetching one line at a time.
-	 */
-	buf = kmalloc(len, GFP_KERNEL);
-	if (!buf)
+	if (WARN_ON_ONCE(cpp != 2 && cpp != 4))
 		return;
 
+	if (!cached)
+		buf = kmalloc(len, GFP_KERNEL);
+
+	src += clip_offset(clip, fb->pitches[0], cpp);
+
 	for (y = clip->y1; y < clip->y2; y++) {
-		src = vaddr + (y * fb->pitches[0]);
-		src += clip->x1;
-		memcpy(buf, src, len);
-		src = buf;
-		for (x = clip->x1; x < clip->x2; x++)
-			*dst++ = swab16(*src++);
+		if (buf) {
+			memcpy(buf, src, len);
+			src16 = buf;
+			src32 = buf;
+		} else {
+			src16 = src;
+			src32 = src;
+		}
+
+		for (x = clip->x1; x < clip->x2; x++) {
+			if (cpp == 4)
+				*dst32++ = swab32(*src32++);
+			else
+				*dst16++ = swab16(*src16++);
+		}
+
+		src += fb->pitches[0];
 	}
 
 	kfree(buf);
 }
-EXPORT_SYMBOL(drm_fb_swab16);
+EXPORT_SYMBOL(drm_fb_swab);
 
 static void drm_fb_xrgb8888_to_rgb565_line(u16 *dbuf, u32 *sbuf,
 					   unsigned int pixels,
diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index 69e2b4122ce4..1447e26c0145 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -217,7 +217,7 @@ int mipi_dbi_buf_copy(void *dst, struct drm_framebuffer *fb,
 	switch (fb->format->format) {
 	case DRM_FORMAT_RGB565:
 		if (swap)
-			drm_fb_swab16(dst, src, fb, clip);
+			drm_fb_swab(dst, src, fb, clip, !import_attach);
 		else
 			drm_fb_memcpy(dst, src, fb, clip);
 		break;
diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
index ac220aa1a245..5f9e37032468 100644
--- a/include/drm/drm_format_helper.h
+++ b/include/drm/drm_format_helper.h
@@ -14,8 +14,8 @@ void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
 void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
 			   struct drm_framebuffer *fb,
 			   struct drm_rect *clip);
-void drm_fb_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
-		   struct drm_rect *clip);
+void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
+		 struct drm_rect *clip, bool cached);
 void drm_fb_xrgb8888_to_rgb565(void *dst, void *vaddr,
 			       struct drm_framebuffer *fb,
 			       struct drm_rect *clip, bool swab);
-- 
2.23.0

[PATCH v2 07/10] drm/format-helper: Add drm_fb_swab()

[Noralf Trønnes]

This replaces drm_fb_swab16() with drm_fb_swab() supporting 16 and 32-bit.
Also make pixel line caching optional.

v2:
- Bail out on cpp != 2 && 4 (Sam)

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_format_helper.c | 61 +++++++++++++++++++----------
 drivers/gpu/drm/drm_mipi_dbi.c      |  2 +-
 include/drm/drm_format_helper.h     |  4 +-
 3 files changed, 44 insertions(+), 23 deletions(-)

diff --git a/drivers/gpu/drm/drm_format_helper.c b/drivers/gpu/drm/drm_format_helper.c
index 0897cb9aeaff..07c9999f1527 100644
--- a/drivers/gpu/drm/drm_format_helper.c
+++ b/drivers/gpu/drm/drm_format_helper.c
@@ -79,39 +79,60 @@ void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
 EXPORT_SYMBOL(drm_fb_memcpy_dstclip);
 
 /**
- * drm_fb_swab16 - Swap bytes into clip buffer
- * @dst: RGB565 destination buffer
- * @vaddr: RGB565 source buffer
+ * drm_fb_swab - Swap bytes into clip buffer
+ * @dst: Destination buffer
+ * @src: Source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
+ * @cached: Source buffer is mapped cached (eg. not write-combined)
+ *
+ * If @cached is false a temporary buffer is used to cache one pixel line at a
+ * time to speed up slow uncached reads.
+ *
+ * This function does not apply clipping on dst, i.e. the destination
+ * is a small buffer containing the clip rect only.
  */
-void drm_fb_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
-		   struct drm_rect *clip)
+void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
+		 struct drm_rect *clip, bool cached)
 {
-	size_t len = (clip->x2 - clip->x1) * sizeof(u16);
+	u8 cpp = fb->format->cpp[0];
+	size_t len = drm_rect_width(clip) * cpp;
+	u16 *src16, *dst16 = dst;
+	u32 *src32, *dst32 = dst;
 	unsigned int x, y;
-	u16 *src, *buf;
+	void *buf = NULL;
 
-	/*
-	 * The cma memory is write-combined so reads are uncached.
-	 * Speed up by fetching one line at a time.
-	 */
-	buf = kmalloc(len, GFP_KERNEL);
-	if (!buf)
+	if (WARN_ON_ONCE(cpp != 2 && cpp != 4))
 		return;
 
+	if (!cached)
+		buf = kmalloc(len, GFP_KERNEL);
+
+	src += clip_offset(clip, fb->pitches[0], cpp);
+
 	for (y = clip->y1; y < clip->y2; y++) {
-		src = vaddr + (y * fb->pitches[0]);
-		src += clip->x1;
-		memcpy(buf, src, len);
-		src = buf;
-		for (x = clip->x1; x < clip->x2; x++)
-			*dst++ = swab16(*src++);
+		if (buf) {
+			memcpy(buf, src, len);
+			src16 = buf;
+			src32 = buf;
+		} else {
+			src16 = src;
+			src32 = src;
+		}
+
+		for (x = clip->x1; x < clip->x2; x++) {
+			if (cpp == 4)
+				*dst32++ = swab32(*src32++);
+			else
+				*dst16++ = swab16(*src16++);
+		}
+
+		src += fb->pitches[0];
 	}
 
 	kfree(buf);
 }
-EXPORT_SYMBOL(drm_fb_swab16);
+EXPORT_SYMBOL(drm_fb_swab);
 
 static void drm_fb_xrgb8888_to_rgb565_line(u16 *dbuf, u32 *sbuf,
 					   unsigned int pixels,
diff --git a/drivers/gpu/drm/drm_mipi_dbi.c b/drivers/gpu/drm/drm_mipi_dbi.c
index 69e2b4122ce4..1447e26c0145 100644
--- a/drivers/gpu/drm/drm_mipi_dbi.c
+++ b/drivers/gpu/drm/drm_mipi_dbi.c
@@ -217,7 +217,7 @@ int mipi_dbi_buf_copy(void *dst, struct drm_framebuffer *fb,
 	switch (fb->format->format) {
 	case DRM_FORMAT_RGB565:
 		if (swap)
-			drm_fb_swab16(dst, src, fb, clip);
+			drm_fb_swab(dst, src, fb, clip, !import_attach);
 		else
 			drm_fb_memcpy(dst, src, fb, clip);
 		break;
diff --git a/include/drm/drm_format_helper.h b/include/drm/drm_format_helper.h
index ac220aa1a245..5f9e37032468 100644
--- a/include/drm/drm_format_helper.h
+++ b/include/drm/drm_format_helper.h
@@ -14,8 +14,8 @@ void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
 void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
 			   struct drm_framebuffer *fb,
 			   struct drm_rect *clip);
-void drm_fb_swab16(u16 *dst, void *vaddr, struct drm_framebuffer *fb,
-		   struct drm_rect *clip);
+void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
+		 struct drm_rect *clip, bool cached);
 void drm_fb_xrgb8888_to_rgb565(void *dst, void *vaddr,
 			       struct drm_framebuffer *fb,
 			       struct drm_rect *clip, bool swab);
-- 
2.23.0

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

[PATCH v2 08/10] drm: Add Generic USB Display driver

[Noralf Trønnes]

This adds a generic USB display driver with the intention that it can be
used with future USB interfaced low end displays/adapters. The Linux
gadget device driver will serve as the canonical device implementation.

The following DRM properties are supported:
- Plane rotation
- Connector TV properties

There is also support for backlight brightness exposed as a backlight
device.

Display modes can be made available to the host driver either as DRM
display modes or through EDID. If both are present, EDID is just passed
on to userspace.

Performance is preferred over color depth, so if the device supports
RGB565, DRM_CAP_DUMB_PREFERRED_DEPTH will return 16.

If the device transfer buffer can't fit an uncompressed framebuffer
update, the update is split up into parts that do fit.

Optimal user experience is achieved by providing damage reports either by
setting FB_DAMAGE_CLIPS on pageflips or calling DRM_IOCTL_MODE_DIRTYFB.

LZ4 compression is used if the device supports it.

The driver supports a one bit monochrome transfer format: R1. This is not
implemented in the gadget driver. It is added in preparation for future
monochrome e-ink displays.

The driver is MIT licensed to smooth the path for any BSD port of the
driver.

v2:
- Use devm_drm_dev_alloc() and drmm_mode_config_init()
- drm_fbdev_generic_setup: Use preferred_bpp=0, 16 was a copy paste error
- The drm_backlight_helper is dropped, copy in the code
- Support protocol version backwards compatibility for device

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 MAINTAINERS                             |   8 +
 drivers/gpu/drm/Kconfig                 |   2 +
 drivers/gpu/drm/Makefile                |   1 +
 drivers/gpu/drm/gud/Kconfig             |  14 +
 drivers/gpu/drm/gud/Makefile            |   4 +
 drivers/gpu/drm/gud/gud_drm_connector.c | 724 ++++++++++++++++++++++++
 drivers/gpu/drm/gud/gud_drm_drv.c       | 641 +++++++++++++++++++++
 drivers/gpu/drm/gud/gud_drm_internal.h  |  66 +++
 drivers/gpu/drm/gud/gud_drm_pipe.c      | 423 ++++++++++++++
 include/drm/gud_drm.h                   | 364 ++++++++++++
 10 files changed, 2247 insertions(+)
 create mode 100644 drivers/gpu/drm/gud/Kconfig
 create mode 100644 drivers/gpu/drm/gud/Makefile
 create mode 100644 drivers/gpu/drm/gud/gud_drm_connector.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_drv.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_internal.h
 create mode 100644 drivers/gpu/drm/gud/gud_drm_pipe.c
 create mode 100644 include/drm/gud_drm.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 5fa9beacee86..7494a21ea41e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5291,6 +5291,14 @@ S:	Maintained
 F:	drivers/gpu/drm/panel/panel-feiyang-fy07024di26a30d.c
 F:	Documentation/devicetree/bindings/display/panel/feiyang,fy07024di26a30d.yaml
 
+DRM DRIVER FOR GENERIC USB DISPLAY
+M:	Noralf Trønnes <noralf@tronnes.org>
+S:	Maintained
+W:	https://github.com/notro/gud/wiki
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	drivers/gpu/drm/gud/
+F:	include/drm/gud_drm.h
+
 DRM DRIVER FOR GRAIN MEDIA GM12U320 PROJECTORS
 M:	Hans de Goede <hdegoede@redhat.com>
 S:	Maintained
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 4bffa08f610a..33e63b68a82d 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -391,6 +391,8 @@ source "drivers/gpu/drm/mcde/Kconfig"
 
 source "drivers/gpu/drm/tidss/Kconfig"
 
+source "drivers/gpu/drm/gud/Kconfig"
+
 # Keep legacy drivers last
 
 menuconfig DRM_LEGACY
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 53d8fa170143..41a87763f0e5 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -124,3 +124,4 @@ obj-$(CONFIG_DRM_PANFROST) += panfrost/
 obj-$(CONFIG_DRM_ASPEED_GFX) += aspeed/
 obj-$(CONFIG_DRM_MCDE) += mcde/
 obj-$(CONFIG_DRM_TIDSS) += tidss/
+obj-y			+= gud/
diff --git a/drivers/gpu/drm/gud/Kconfig b/drivers/gpu/drm/gud/Kconfig
new file mode 100644
index 000000000000..767f1c067ed9
--- /dev/null
+++ b/drivers/gpu/drm/gud/Kconfig
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config DRM_GUD
+	tristate "Generic USB Display"
+	depends on DRM && USB
+	select LZ4_COMPRESS
+	select DRM_KMS_HELPER
+	select DRM_GEM_SHMEM_HELPER
+	select BACKLIGHT_CLASS_DEVICE
+	help
+	  This is a DRM display driver for Generic USB Displays or display
+	  adapters.
+
+	  If M is selected the module will be called gud_drm.
diff --git a/drivers/gpu/drm/gud/Makefile b/drivers/gpu/drm/gud/Makefile
new file mode 100644
index 000000000000..73ed7ef3da94
--- /dev/null
+++ b/drivers/gpu/drm/gud/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+
+gud_drm-objs			:= gud_drm_drv.o gud_drm_pipe.o gud_drm_connector.o
+obj-$(CONFIG_DRM_GUD)		+= gud_drm.o
diff --git a/drivers/gpu/drm/gud/gud_drm_connector.c b/drivers/gpu/drm/gud/gud_drm_connector.c
new file mode 100644
index 000000000000..eba1665582f4
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_connector.c
@@ -0,0 +1,724 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/backlight.h>
+
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_encoder.h>
+#include <drm/drm_file.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+struct gud_drm_connector {
+	struct drm_connector connector;
+	struct drm_encoder encoder;
+	struct backlight_device *backlight;
+
+	u32 flags;
+
+	/* Supported properties */
+	u16 *properties;
+	unsigned int num_properties;
+
+	/* Initial gadget tv state if applicable, applied on state reset */
+	struct drm_tv_connector_state initial_tv_state;
+
+	/*
+	 * Initial gadget backlight brightness if applicable, applied on state reset.
+	 * The value -ENODEV is used internally to signal no backlight.
+	 */
+	int initial_brightness;
+
+	/* Supported display modes in transfer format */
+	struct gud_drm_display_mode *modes;
+	unsigned int num_modes;
+
+	/* EDID */
+	void *edid;
+	size_t edid_len;
+};
+
+static inline struct gud_drm_connector *to_gud_drm_connector(struct drm_connector *connector)
+{
+	return container_of(connector, struct gud_drm_connector, connector);
+}
+
+static int gud_drm_connector_backlight_update_status(struct backlight_device *bd)
+{
+	struct drm_connector *connector = bl_get_data(bd);
+	struct drm_connector_state *connector_state;
+	struct drm_device *dev = connector->dev;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_atomic_state *state;
+	int ret;
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return -ENOMEM;
+
+	drm_modeset_acquire_init(&ctx, 0);
+	state->acquire_ctx = &ctx;
+retry:
+	connector_state = drm_atomic_get_connector_state(state, connector);
+	if (IS_ERR(connector_state)) {
+		ret = PTR_ERR(connector_state);
+		goto out;
+	}
+
+	/* Reuse tv.brightness to avoid having to subclass */
+	connector_state->tv.brightness = bd->props.brightness;
+
+	ret = drm_atomic_commit(state);
+out:
+	if (ret == -EDEADLK) {
+		drm_atomic_state_clear(state);
+		drm_modeset_backoff(&ctx);
+		goto retry;
+	}
+
+	drm_atomic_state_put(state);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+}
+
+static int gud_drm_connector_backlight_get_brightness(struct backlight_device *bd)
+{
+	struct drm_connector *connector = bl_get_data(bd);
+	struct drm_device *dev = connector->dev;
+	int brightness;
+
+	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+	brightness = connector->state->tv.brightness;
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+	return brightness;
+}
+
+static const struct backlight_ops gud_drm_connector_backlight_ops = {
+	.get_brightness = gud_drm_connector_backlight_get_brightness,
+	.update_status	= gud_drm_connector_backlight_update_status,
+};
+
+static int gud_drm_connector_backlight_register(struct gud_drm_connector *gconn)
+{
+	struct drm_connector *connector = &gconn->connector;
+	struct backlight_device *bd;
+	const char *name;
+	const struct backlight_properties props = {
+		.type = BACKLIGHT_RAW,
+		.scale = BACKLIGHT_SCALE_NON_LINEAR,
+		.max_brightness = 100,
+	};
+
+	name = kasprintf(GFP_KERNEL, "card%d-%s-backlight",
+			 connector->dev->primary->index, connector->name);
+	if (!name)
+		return -ENOMEM;
+
+	bd = backlight_device_register(name, connector->kdev, connector,
+				       &gud_drm_connector_backlight_ops, &props);
+	kfree(name);
+	if (IS_ERR(bd))
+		return PTR_ERR(bd);
+
+	gconn->backlight = bd;
+
+	return 0;
+}
+
+static void gud_drm_connector_modes_clear(struct gud_drm_connector *gconn)
+{
+	kfree(gconn->modes);
+	gconn->modes = NULL;
+	gconn->num_modes = 0;
+}
+
+static int gud_drm_connector_modes_get(struct gud_drm_connector *gconn, unsigned int num_modes)
+{
+	struct gud_drm_device *gdrm = to_gud_drm_device(gconn->connector.dev);
+	unsigned int index = gconn->connector.index;
+	int ret = 0;
+
+	if (!num_modes)
+		goto clear;
+
+	gud_drm_connector_modes_clear(gconn);
+
+	gconn->modes = kmalloc_array(num_modes, sizeof(*gconn->modes), GFP_KERNEL);
+	if (!gconn->modes)
+		return -ENOMEM;
+
+	gconn->num_modes = num_modes;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_MODES, index,
+			      gconn->modes, num_modes * sizeof(*gconn->modes));
+	if (ret)
+		goto clear;
+
+	return 0;
+clear:
+	gud_drm_connector_modes_clear(gconn);
+
+	return ret;
+}
+
+static void gud_drm_connector_edid_clear(struct gud_drm_connector *gconn)
+{
+	kfree(gconn->edid);
+	gconn->edid = NULL;
+	gconn->edid_len = 0;
+}
+
+static int gud_drm_connector_edid_get(struct gud_drm_connector *gconn, size_t len)
+{
+	struct gud_drm_device *gdrm = to_gud_drm_device(gconn->connector.dev);
+	unsigned int index = gconn->connector.index;
+	int ret = 0;
+
+	if (!len)
+		goto clear;
+
+	gud_drm_connector_edid_clear(gconn);
+
+	gconn->edid = kmalloc(len, GFP_KERNEL);
+	if (!gconn->edid)
+		return -ENOMEM;
+
+	gconn->edid_len = len;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_EDID, index, gconn->edid, len);
+	if (ret)
+		goto clear;
+
+	return 0;
+clear:
+	gud_drm_connector_edid_clear(gconn);
+
+	return ret;
+}
+
+static int gud_drm_connector_detect_safe(struct drm_connector *connector, bool force)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+	struct gud_drm_device *gdrm = to_gud_drm_device(connector->dev);
+	struct gud_drm_req_get_connector_status req;
+	u16 num_modes, edid_len;
+	int status, ret;
+	bool changed;
+
+	if (force) {
+		ret = gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_CONNECTOR_FORCE_DETECT,
+				      connector->index, NULL, 0);
+		if (ret)
+			goto free;
+	}
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_STATUS,
+			      connector->index, &req, sizeof(req));
+	if (ret)
+		goto free;
+
+	changed = req.status & GUD_DRM_CONNECTOR_STATUS_CHANGED;
+	status = req.status & GUD_DRM_CONNECTOR_STATUS_MASK;
+	if (status > connector_status_unknown)
+		status = connector_status_unknown;
+	num_modes = le16_to_cpu(req.num_modes);
+	edid_len = le16_to_cpu(req.edid_len);
+
+	if (!num_modes && !edid_len) {
+		ret = connector_status_disconnected;
+		goto free;
+	}
+
+	if (!changed && connector->status == status &&
+	    gconn->num_modes == num_modes && gconn->edid_len == edid_len)
+		return status;
+
+	ret = gud_drm_connector_modes_get(gconn, num_modes);
+	if (ret)
+		goto free;
+
+	ret = gud_drm_connector_edid_get(gconn, edid_len);
+	if (ret)
+		goto free;
+
+	return status;
+free:
+	gud_drm_connector_modes_clear(gconn);
+	gud_drm_connector_edid_clear(gconn);
+
+	return ret < 0 ? connector_status_unknown : ret;
+}
+
+static int gud_drm_connector_detect(struct drm_connector *connector,
+				    struct drm_modeset_acquire_ctx *ctx, bool force)
+{
+	int idx, ret;
+
+	if (!drm_dev_enter(connector->dev, &idx))
+		return -ENODEV;
+
+	ret = gud_drm_connector_detect_safe(connector, force);
+
+	drm_dev_exit(idx);
+
+	return ret;
+}
+
+static int gud_drm_connector_get_modes(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+	unsigned int i, num_modes = 0;
+
+	if (!gconn->num_modes)
+		return drm_add_edid_modes(connector, gconn->edid);
+
+	for (i = 0; i < gconn->num_modes; i++) {
+		struct drm_display_mode *mode;
+
+		mode = drm_mode_create(connector->dev);
+		if (!mode)
+			goto out;
+
+		gud_drm_to_display_mode(mode, &gconn->modes[i]);
+
+		drm_mode_probed_add(connector, mode);
+		num_modes++;
+	}
+out:
+	if (gconn->edid_len)
+		drm_connector_update_edid_property(connector, gconn->edid);
+
+	return num_modes;
+}
+
+static int gud_drm_connector_atomic_check(struct drm_connector *connector,
+					  struct drm_atomic_state *state)
+{
+	struct drm_connector_state *new_state;
+	struct drm_crtc_state *new_crtc_state;
+	struct drm_connector_state *old_state;
+
+	new_state = drm_atomic_get_new_connector_state(state, connector);
+	if (!new_state->crtc)
+		return 0;
+
+	old_state = drm_atomic_get_old_connector_state(state, connector);
+	new_crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);
+
+	if (old_state->tv.subconnector != new_state->tv.subconnector ||
+	    old_state->tv.margins.left != new_state->tv.margins.left ||
+	    old_state->tv.margins.right != new_state->tv.margins.right ||
+	    old_state->tv.margins.top != new_state->tv.margins.top ||
+	    old_state->tv.margins.bottom != new_state->tv.margins.bottom ||
+	    old_state->tv.mode != new_state->tv.mode ||
+	    old_state->tv.brightness != new_state->tv.brightness ||
+	    old_state->tv.contrast != new_state->tv.contrast ||
+	    old_state->tv.flicker_reduction != new_state->tv.flicker_reduction ||
+	    old_state->tv.overscan != new_state->tv.overscan ||
+	    old_state->tv.saturation != new_state->tv.saturation ||
+	    old_state->tv.hue != new_state->tv.hue)
+		new_crtc_state->connectors_changed = true;
+
+	return 0;
+}
+
+static const struct drm_connector_helper_funcs gud_drm_connector_helper_funcs = {
+	.detect_ctx = gud_drm_connector_detect,
+	.get_modes = gud_drm_connector_get_modes,
+	.atomic_check = gud_drm_connector_atomic_check,
+};
+
+static int gud_drm_connector_late_register(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	if (gconn->initial_brightness < 0)
+		return 0;
+
+	return gud_drm_connector_backlight_register(gconn);
+}
+
+static void gud_drm_connector_early_unregister(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	backlight_device_unregister(gconn->backlight);
+}
+
+static void gud_drm_connector_destroy(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	drm_connector_cleanup(connector);
+	gud_drm_connector_modes_clear(gconn);
+	gud_drm_connector_edid_clear(gconn);
+	kfree(gconn->properties);
+	kfree(gconn);
+}
+
+static void gud_drm_connector_reset(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	drm_atomic_helper_connector_reset(connector);
+	connector->state->tv = gconn->initial_tv_state;
+	/* Set margins from command line */
+	drm_atomic_helper_connector_tv_reset(connector);
+	if (gconn->initial_brightness >= 0)
+		connector->state->tv.brightness = gconn->initial_brightness;
+}
+
+static const struct drm_connector_funcs gud_drm_connector_funcs = {
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.late_register = gud_drm_connector_late_register,
+	.early_unregister = gud_drm_connector_early_unregister,
+	.destroy = gud_drm_connector_destroy,
+	.reset = gud_drm_connector_reset,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+/*
+ * The tv.mode property is shared among the connectors and its enum names are
+ * driver specific. This means that if more than one connector uses tv.mode,
+ * the enum names has to be the same.
+ */
+static int gud_drm_connector_add_tv_mode(struct gud_drm_device *gdrm,
+					 struct drm_connector *connector, u64 val)
+{
+	unsigned int i, num_modes;
+	const char **modes;
+	size_t buf_len;
+	char *buf;
+	int ret;
+
+	num_modes = val >> GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT;
+
+	if (!num_modes)
+		return -EINVAL;
+
+	buf_len = num_modes * DRM_PROP_NAME_LEN;
+	modes = kmalloc_array(num_modes, sizeof(*modes), GFP_KERNEL);
+	buf = kmalloc(buf_len, GFP_KERNEL);
+	if (!modes || !buf) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_TV_MODE_VALUES,
+			      connector->index, buf, buf_len);
+	if (ret)
+		goto free;
+
+	for (i = 0; i < num_modes; i++)
+		modes[i] = &buf[i * DRM_PROP_NAME_LEN];
+
+	ret = drm_mode_create_tv_properties(connector->dev, num_modes, modes);
+free:
+	kfree(modes);
+	kfree(buf);
+
+	return ret;
+}
+
+static struct drm_property *
+gud_drm_connector_property_lookup(struct drm_connector *connector, u16 prop)
+{
+	struct drm_mode_config *config = &connector->dev->mode_config;
+
+	switch (prop) {
+	case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+		return config->tv_select_subconnector_property;
+	case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+		return config->tv_left_margin_property;
+	case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+		return config->tv_right_margin_property;
+	case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+		return config->tv_top_margin_property;
+	case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+		return config->tv_bottom_margin_property;
+	case GUD_DRM_PROPERTY_TV_MODE:
+		return config->tv_mode_property;
+	case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+		return config->tv_brightness_property;
+	case GUD_DRM_PROPERTY_TV_CONTRAST:
+		return config->tv_contrast_property;
+	case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+		return config->tv_flicker_reduction_property;
+	case GUD_DRM_PROPERTY_TV_OVERSCAN:
+		return config->tv_overscan_property;
+	case GUD_DRM_PROPERTY_TV_SATURATION:
+		return config->tv_saturation_property;
+	case GUD_DRM_PROPERTY_TV_HUE:
+		return config->tv_hue_property;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+}
+
+static unsigned int *gud_drm_connector_tv_state_val(u16 prop, struct drm_tv_connector_state *state)
+{
+	switch (prop) {
+	case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+		return &state->subconnector;
+	case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+		return &state->margins.left;
+	case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+		return &state->margins.right;
+	case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+		return &state->margins.top;
+	case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+		return &state->margins.bottom;
+	case GUD_DRM_PROPERTY_TV_MODE:
+		return &state->mode;
+	case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+		return &state->brightness;
+	case GUD_DRM_PROPERTY_TV_CONTRAST:
+		return &state->contrast;
+	case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+		return &state->flicker_reduction;
+	case GUD_DRM_PROPERTY_TV_OVERSCAN:
+		return &state->overscan;
+	case GUD_DRM_PROPERTY_TV_SATURATION:
+		return &state->saturation;
+	case GUD_DRM_PROPERTY_TV_HUE:
+		return &state->hue;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+}
+
+static int gud_drm_connector_add_properties(struct gud_drm_device *gdrm,
+					    struct gud_drm_connector *gconn,
+					    unsigned int num_properties)
+{
+	struct drm_device *drm = &gdrm->drm;
+	struct drm_connector *connector = &gconn->connector;
+	struct gud_drm_property *properties;
+	bool need_tv_props = false;
+	unsigned int i;
+	int ret;
+
+	gconn->properties = kcalloc(num_properties, sizeof(*gconn->properties), GFP_KERNEL);
+	if (!gconn->properties)
+		return -ENOMEM;
+
+	properties = kcalloc(num_properties, sizeof(*properties), GFP_KERNEL);
+	if (!properties)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_PROPERTIES, connector->index,
+			      properties, num_properties * sizeof(*properties));
+	if (ret)
+		goto out;
+
+	for (i = 0; i < num_properties; i++) {
+		u16 prop = le16_to_cpu(properties[i].prop);
+		u64 val = le64_to_cpu(properties[i].val);
+
+		drm_dbg(drm, "property: %u = %llu(0x%llx)\n", prop, val, val);
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+			ret = drm_mode_create_tv_margin_properties(drm);
+			if (ret)
+				goto out;
+			break;
+		case GUD_DRM_PROPERTY_TV_MODE:
+			ret = gud_drm_connector_add_tv_mode(gdrm, connector, val);
+			if (ret)
+				goto out;
+			break;
+		case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_CONTRAST:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_OVERSCAN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_SATURATION:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_HUE:
+			need_tv_props = true;
+			break;
+		case GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS:
+			if (val > 100) {
+				ret = -EINVAL;
+				goto out;
+			}
+			gconn->initial_brightness = val;
+			break;
+		default:
+			/* New ones might show up in future devices, skip those we don't know. */
+			drm_dbg(drm, "Unknown property: %u\n", prop);
+			continue;
+		}
+
+		gconn->properties[gconn->num_properties++] = prop;
+	}
+
+	if (!gconn->num_properties)
+		goto out;
+
+	if (need_tv_props) {
+		/* This is a no-op if already added. */
+		ret = drm_mode_create_tv_properties(drm, 0, NULL);
+		if (ret)
+			goto out;
+	}
+
+	for (i = 0; i < num_properties; i++) {
+		u16 prop = le16_to_cpu(properties[i].prop);
+		u64 val = le64_to_cpu(properties[i].val);
+		struct drm_property *property;
+		unsigned int *state_val;
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS:
+			/* not a DRM property */
+			continue;
+		case GUD_DRM_PROPERTY_TV_MODE:
+			val = val & (BIT(GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT) - 1);
+			break;
+		}
+
+		property = gud_drm_connector_property_lookup(connector, prop);
+		if (IS_ERR(property))
+			continue;
+
+		state_val = gud_drm_connector_tv_state_val(prop, &gconn->initial_tv_state);
+		if (IS_ERR(state_val))
+			continue;
+
+		*state_val = val;
+		drm_object_attach_property(&connector->base, property, 0);
+	}
+out:
+	kfree(properties);
+
+	return ret;
+}
+
+int gud_drm_connector_fill_properties(struct drm_connector *connector,
+				      struct drm_connector_state *connector_state,
+				      struct gud_drm_property *properties)
+{
+	struct gud_drm_connector *gconn;
+	unsigned int i;
+
+	gconn = to_gud_drm_connector(connector);
+
+	/* Only interested in the count? */
+	if (!connector_state)
+		return gconn->num_properties;
+
+	for (i = 0; i < gconn->num_properties; i++) {
+		u16 prop = gconn->properties[i];
+		u64 val;
+
+		if (prop == GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS) {
+			val = connector_state->tv.brightness;
+		} else {
+			unsigned int *state_val;
+
+			state_val = gud_drm_connector_tv_state_val(prop, &connector_state->tv);
+			if (WARN_ON_ONCE(IS_ERR(state_val)))
+				return PTR_ERR(state_val);
+
+			val = *state_val;
+		}
+
+		properties[i].prop = cpu_to_le16(prop);
+		properties[i].val = cpu_to_le64(val);
+	}
+
+	return gconn->num_properties;
+}
+
+int gud_drm_connector_create(struct gud_drm_device *gdrm, unsigned int index)
+{
+	struct gud_drm_req_get_connector desc;
+	struct drm_device *drm = &gdrm->drm;
+	struct gud_drm_connector *gconn;
+	struct drm_connector *connector;
+	struct drm_encoder *encoder;
+	int ret;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR, index, &desc, sizeof(desc));
+	if (ret)
+		return ret;
+
+	drm_dbg(drm, "index=%u type=%u flags=0x%x num_properties=%u\n", index,
+		desc.connector_type, le32_to_cpu(desc.flags), desc.num_properties);
+
+	/* REVISIT: This needs to be updated as new types are added */
+	if (desc.connector_type > DRM_MODE_CONNECTOR_SPI)
+		return -EINVAL;
+
+	gconn = kzalloc(sizeof(*gconn), GFP_KERNEL);
+	if (!gconn)
+		return -ENOMEM;
+
+	gconn->initial_brightness = -ENODEV;
+	gconn->flags = le32_to_cpu(desc.flags);
+	connector = &gconn->connector;
+
+	drm_connector_helper_add(connector, &gud_drm_connector_helper_funcs);
+	ret = drm_connector_init(drm, connector, &gud_drm_connector_funcs, desc.connector_type);
+	if (ret) {
+		kfree(connector);
+		return ret;
+	}
+
+	if (WARN_ON(connector->index != index))
+		return -EINVAL;
+
+	if (gconn->flags & GUD_DRM_CONNECTOR_FLAGS_POLL)
+		connector->polled = (DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT);
+
+	if (desc.num_properties) {
+		ret = gud_drm_connector_add_properties(gdrm, gconn, desc.num_properties);
+		if (ret) {
+			dev_err(drm->dev, "Failed to add connector/%u properties\n", index);
+			return ret;
+		}
+	}
+
+	/* The first connector is attached to the existing simple pipe encoder */
+	if (!connector->index) {
+		encoder = &gdrm->pipe.encoder;
+	} else {
+		encoder = &gconn->encoder;
+
+		ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_NONE);
+		if (ret)
+			return ret;
+
+		encoder->possible_crtcs = 1;
+	}
+
+	return drm_connector_attach_encoder(connector, encoder);
+}
diff --git a/drivers/gpu/drm/gud/gud_drm_drv.c b/drivers/gpu/drm/gud/gud_drm_drv.c
new file mode 100644
index 000000000000..3f2e8c1d9a38
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_drv.c
@@ -0,0 +1,641 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/lz4.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/string_helpers.h>
+#include <linux/usb.h>
+#include <linux/workqueue.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_debugfs.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+/* Only used internally */
+static const struct drm_format_info gud_drm_format_r1 = {
+	.format = GUD_DRM_FORMAT_R1,
+	.num_planes = 1,
+	.char_per_block = { 1, 0, 0 },
+	.block_w = { 8, 0, 0 },
+	.block_h = { 1, 0, 0 },
+	.hsub = 1,
+	.vsub = 1,
+};
+
+static int gud_drm_usb_control_msg(struct usb_device *usb, u8 ifnum, bool in,
+				   u8 request, u16 value, void *buf, size_t len,
+				   bool check_len)
+{
+	u8 requesttype = USB_TYPE_VENDOR | USB_RECIP_INTERFACE;
+	unsigned int pipe;
+	int ret;
+
+	if (in) {
+		pipe = usb_rcvctrlpipe(usb, 0);
+		requesttype |= USB_DIR_IN;
+	} else {
+		pipe = usb_sndctrlpipe(usb, 0);
+		requesttype |= USB_DIR_OUT;
+	}
+
+	ret = usb_control_msg(usb, pipe, request, requesttype, value,
+			      ifnum, buf, len, USB_CTRL_GET_TIMEOUT);
+
+	if (check_len && ret >= 0) {
+		if (ret != len)
+			ret = -EIO;
+		else
+			ret = 0;
+	}
+
+	return ret;
+}
+
+static int gud_get_vendor_descriptor(struct usb_interface *interface,
+				     struct gud_drm_display_descriptor *desc)
+{
+	u8 ifnum = interface->cur_altsetting->desc.bInterfaceNumber;
+	struct usb_device *usb = interface_to_usbdev(interface);
+	void *buf;
+	int ret;
+
+	buf = kmalloc(sizeof(*desc), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_control_msg(usb, ifnum, true, USB_REQ_GET_DESCRIPTOR,
+				      GUD_DRM_USB_DT_DISPLAY << 8, buf, sizeof(*desc), false);
+
+	memcpy(desc, buf, sizeof(*desc));
+	kfree(buf);
+
+	if (ret < 0)
+		return ret;
+
+	if (ret != sizeof(*desc) || desc->bLength != sizeof(*desc) ||
+	    desc->bDescriptorType != GUD_DRM_USB_DT_DISPLAY)
+		return -ENODATA;
+
+	DRM_DEV_DEBUG_DRIVER(&interface->dev,
+			     "Version=%u Compression=0x%x NumFormats=%u NumConnectors=%u MaxBufferSizeOrder=%u\n",
+			     desc->bVersion, desc->bCompression, desc->bNumFormats,
+			     desc->bNumConnectors, desc->bMaxBufferSizeOrder);
+
+	if (!desc->bVersion || !desc->bNumFormats || !desc->bNumConnectors ||
+	    !desc->bMaxBufferSizeOrder || !desc->dwMaxWidth || !desc->dwMaxHeight ||
+	    le32_to_cpu(desc->dwMinWidth) > le32_to_cpu(desc->dwMaxWidth) ||
+	    le32_to_cpu(desc->dwMinHeight) > le32_to_cpu(desc->dwMaxHeight))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int gud_usb_get_status(struct gud_drm_device *gdrm)
+{
+	struct gud_drm_req_get_status *status = gdrm->status_buf;
+	int ret, status_retries = 2000 / 5; /* maximum wait ~2 seconds */
+	unsigned long delay = 500;
+
+	/*
+	 * Poll due to lack of data/status stage control on the gadget side.
+	 *
+	 * If we did not use polling and gave up here after waiting 2 seconds,
+	 * the worker in the gadget would finally get to queuing up the status
+	 * respons, but by that time the host has moved on. The gadget side
+	 * (at least dwc2) would now be left in a non-recoverable state.
+	 *
+	 * Worst case commit timeout in DRM can be tens of seconds (wait for
+	 * various _done completions).
+	 */
+	while (status_retries--) {
+		ret = gud_drm_usb_control_msg(gdrm->usb, gdrm->ifnum, true, USB_REQ_GET_STATUS,
+					      0, status, sizeof(*status), true);
+		if (ret)
+			return ret;
+
+		if (!(status->flags & GUD_DRM_STATUS_PENDING))
+			return -status->errno;
+
+		usleep_range(delay, delay + 1000);
+
+		if (delay < 4500)
+			delay += 1000;
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int gud_usb_transfer(struct gud_drm_device *gdrm, bool in, u8 request,
+			    u16 index, void *buf, size_t len)
+{
+	int idx, ret;
+
+	drm_dbg(&gdrm->drm, "%s: request=0x%x index=%u len=%zu\n",
+		in ? "get" : "set", request, index, len);
+
+	if (len > GUD_DRM_MAX_TRANSFER_SIZE)
+		return -ENOMEM;
+
+	if (!drm_dev_enter(&gdrm->drm, &idx))
+		return -ENODEV;
+
+	mutex_lock(&gdrm->ctrl_lock);
+
+	if (!in && buf)
+		memcpy(gdrm->ctrl_msg_buf, buf, len);
+
+	ret = gud_drm_usb_control_msg(gdrm->usb, gdrm->ifnum, in, request, index,
+				      gdrm->ctrl_msg_buf, len, true);
+
+	/*
+	 * OUT transfers are processed in a worker on the gadget side after
+	 * reception so we always need to check status. IN transfers are
+	 * processed in the interrupt handler and will halt on error letting us
+	 * know something went wrong.
+	 */
+	if (ret || !in) {
+		ret = gud_usb_get_status(gdrm);
+		if (ret)
+			goto error;
+	}
+
+	if (in && buf)
+		memcpy(buf, gdrm->ctrl_msg_buf, len);
+error:
+	if (ret) {
+		drm_dbg(&gdrm->drm, "ret=%d\n", ret);
+		gdrm->stats_num_errors++;
+	}
+
+	mutex_unlock(&gdrm->ctrl_lock);
+	drm_dev_exit(idx);
+
+	return ret;
+}
+
+int gud_drm_usb_get(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len)
+{
+	return gud_usb_transfer(gdrm, true, request, index, buf, len);
+}
+
+int gud_drm_usb_set(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len)
+{
+	return gud_usb_transfer(gdrm, false, request, index, buf, len);
+}
+
+int gud_drm_usb_write8(struct gud_drm_device *gdrm, u8 request, u8 val)
+{
+	return gud_drm_usb_set(gdrm, request, 0, &val, sizeof(val));
+}
+
+static int gud_drm_usb_read32(struct gud_drm_device *gdrm, u8 request,
+			      u32 *vals, unsigned int num_vals)
+{
+	unsigned int i;
+	int ret;
+
+	ret = gud_drm_usb_get(gdrm, request, 0, vals, num_vals * sizeof(*vals));
+	if (ret)
+		return ret;
+
+	for (i = 0; i < num_vals; i++)
+		vals[i] = le32_to_cpu((__le32)vals[i]);
+
+	return 0;
+}
+
+static int gud_drm_get_properties(struct gud_drm_device *gdrm, unsigned int num_properties)
+{
+	struct gud_drm_property *properties;
+	unsigned int i;
+	int ret;
+
+	if (!num_properties)
+		return 0;
+
+	gdrm->properties = kcalloc(num_properties, sizeof(*gdrm->properties), GFP_KERNEL);
+	if (!gdrm->properties)
+		return -ENOMEM;
+
+	properties = kcalloc(num_properties, sizeof(*properties), GFP_KERNEL);
+	if (!properties)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_PROPERTIES, 0,
+			      properties, num_properties * sizeof(*properties));
+	if (ret)
+		goto out;
+
+	for (i = 0; i < num_properties; i++) {
+		u16 prop = le16_to_cpu(properties[i].prop);
+		u64 val = le64_to_cpu(properties[i].val);
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_ROTATION:
+			ret = drm_plane_create_rotation_property(&gdrm->pipe.plane,
+								 DRM_MODE_ROTATE_0, val);
+			break;
+		default:
+			/* New ones might show up in future devices, skip those we don't know. */
+			drm_dbg(&gdrm->drm, "Unknown property: %u\n", prop);
+			continue;
+		}
+
+		if (ret)
+			goto out;
+
+		gdrm->properties[gdrm->num_properties++] = prop;
+	}
+out:
+	kfree(properties);
+
+	return ret;
+}
+
+static struct drm_gem_object *
+gud_drm_driver_gem_create_object(struct drm_device *dev, size_t size)
+{
+	struct drm_gem_shmem_object *shmem;
+
+	shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
+	if (!shmem)
+		return NULL;
+
+	/*
+	 * This doesn't make a difference on x86, but on ARM (pi4) it was
+	 * necessary to avoid black lines all over and it made it possible to
+	 * compress directly from the framebuffer without performance drop.
+	 */
+	shmem->map_cached = true;
+
+	return &shmem->base;
+}
+
+static int gud_drm_stats_debugfs(struct seq_file *m, void *data)
+{
+	struct drm_info_node *node = m->private;
+	struct gud_drm_device *gdrm = to_gud_drm_device(node->minor->dev);
+	char buf[10];
+
+	string_get_size(gdrm->bulk_len, 1, STRING_UNITS_2, buf, sizeof(buf));
+	seq_printf(m, "Max buffer size: %s\n", buf);
+	seq_printf(m, "Number of errors:  %u\n", gdrm->stats_num_errors);
+
+	seq_puts(m, "Compression:      ");
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4)
+		seq_puts(m, " lz4");
+	seq_puts(m, "\n");
+
+	if (gdrm->compression) {
+		u64 remainder;
+		u64 ratio = div64_u64_rem(gdrm->stats_length, gdrm->stats_actual_length,
+					  &remainder);
+		u64 ratio_frac = div64_u64(remainder * 10, gdrm->stats_actual_length);
+
+		seq_printf(m, "Compression ratio: %llu.%llu\n", ratio, ratio_frac);
+	}
+
+	return 0;
+}
+
+static const struct drm_info_list gud_drm_debugfs_list[] = {
+	{ "stats", gud_drm_stats_debugfs, 0, NULL },
+};
+
+static void gud_drm_driver_debugfs_init(struct drm_minor *minor)
+{
+	drm_debugfs_create_files(gud_drm_debugfs_list, ARRAY_SIZE(gud_drm_debugfs_list),
+				 minor->debugfs_root, minor);
+}
+
+static const struct drm_simple_display_pipe_funcs gud_drm_pipe_funcs = {
+	.check      = gud_drm_pipe_check,
+	.update	    = gud_drm_pipe_update,
+	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+static const struct drm_mode_config_funcs gud_drm_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static const uint64_t gud_drm_pipe_modifiers[] = {
+	DRM_FORMAT_MOD_LINEAR,
+	DRM_FORMAT_MOD_INVALID
+};
+
+DEFINE_DRM_GEM_FOPS(gud_drm_fops);
+
+static struct drm_driver gud_drm_driver = {
+	.driver_features	= DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
+	.fops			= &gud_drm_fops,
+	.gem_create_object	= gud_drm_driver_gem_create_object,
+	DRM_GEM_SHMEM_DRIVER_OPS,
+	.debugfs_init		= gud_drm_driver_debugfs_init,
+
+	.name			= "gud_drm",
+	.desc			= "Generic USB Display",
+	.date			= "20200422",
+	.major			= 1,
+	.minor			= 0,
+};
+
+static void gud_drm_free_buffers_and_mutex(void *data)
+{
+	struct gud_drm_device *gdrm = data;
+
+	/* Access to these are protected by drm_dev_enter/exit */
+
+	kfree(gdrm->properties);
+	vfree(gdrm->compress_buf);
+	kfree(gdrm->bulk_buf);
+	kfree(gdrm->ctrl_msg_buf);
+	gdrm->properties = NULL;
+	gdrm->compress_buf = NULL;
+	gdrm->bulk_buf = NULL;
+	gdrm->ctrl_msg_buf = NULL;
+
+	mutex_destroy(&gdrm->ctrl_lock);
+	mutex_destroy(&gdrm->damage_lock);
+}
+
+static int gud_drm_probe(struct usb_interface *interface,
+			 const struct usb_device_id *id)
+{
+	u8 ifnum = interface->cur_altsetting->desc.bInterfaceNumber;
+	struct usb_device *usb = interface_to_usbdev(interface);
+	const struct drm_format_info *xrgb8888_emulation_format = NULL;
+	u32 *formats, *formats_dev, num_connectors, num_formats = 0;
+	bool rgb565_supported = false, rgb8888_supported = false;
+	struct usb_endpoint_descriptor *bulk_out;
+	struct gud_drm_display_descriptor desc;
+	struct device *dev = &interface->dev;
+	struct gud_drm_device *gdrm;
+	struct drm_device *drm;
+	size_t max_buffer_size;
+	int ret, i;
+
+	ret = usb_find_bulk_out_endpoint(interface->cur_altsetting, &bulk_out);
+	if (ret)
+		return ret;
+
+	ret = gud_get_vendor_descriptor(interface, &desc);
+	if (ret) {
+		DRM_DEV_DEBUG_DRIVER(dev, "Not a display interface: ret=%d\n", ret);
+		return -ENODEV;
+	}
+
+	if (desc.bVersion > 1) {
+		u8 *version = kmalloc(sizeof(*version), GFP_KERNEL);
+
+		if (!version)
+			return -ENOMEM;
+
+		/* Check if the device can support us */
+		*version = 1;
+		ret = gud_drm_usb_control_msg(usb, ifnum, false, GUD_DRM_USB_REQ_SET_VERSION,
+					      0, version, sizeof(*version), true);
+		kfree(version);
+		if (ret) {
+			dev_err(dev, "Protocol version %u is not supported\n", desc.bVersion);
+			return -EPROTONOSUPPORT;
+		}
+
+		desc.bVersion = 1;
+	}
+
+	num_connectors = desc.bNumConnectors;
+	max_buffer_size = 1 << desc.bMaxBufferSizeOrder;
+
+	gdrm = devm_drm_dev_alloc(dev, &gud_drm_driver, struct gud_drm_device, drm);
+	if (IS_ERR(gdrm))
+		return PTR_ERR(gdrm);
+
+	drm = &gdrm->drm;
+	drm->mode_config.funcs = &gud_drm_mode_config_funcs;
+	ret = drmm_mode_config_init(drm);
+	if (ret)
+		return ret;
+
+	gdrm->usb = usb;
+	gdrm->ifnum = ifnum;
+	gdrm->compression = desc.bCompression & GUD_DRM_COMPRESSION_LZ4;
+
+	mutex_init(&gdrm->ctrl_lock);
+	mutex_init(&gdrm->damage_lock);
+	INIT_WORK(&gdrm->work, gud_drm_work);
+	gud_drm_clear_damage(gdrm);
+
+	/*
+	 * devm_kmalloc() places struct devres at the beginning of the buffer it
+	 * allocates. This can waste a lot of memory when allocating
+	 * power-of-two sized buffers. Asking for 4k would actually allocate 8k.
+	 */
+
+	ret = devm_add_action_or_reset(dev, gud_drm_free_buffers_and_mutex, gdrm);
+	if (ret)
+		return ret;
+
+	gdrm->ctrl_msg_buf = kmalloc(GUD_DRM_MAX_TRANSFER_SIZE, GFP_KERNEL);
+	gdrm->status_buf = devm_kzalloc(dev, sizeof(struct gud_drm_req_get_status), GFP_KERNEL);
+	if (!gdrm->ctrl_msg_buf || !gdrm->status_buf)
+		return -ENOMEM;
+retry:
+	gdrm->bulk_buf = kmalloc(max_buffer_size, GFP_KERNEL);
+	if (!gdrm->bulk_buf) {
+		max_buffer_size /= 2;
+		if (max_buffer_size < SZ_2M) { /* Give up if we can't do 1024x768 RGB565 */
+			return -ENOMEM;
+		}
+		goto retry;
+	}
+
+	gdrm->bulk_pipe = usb_sndbulkpipe(gdrm->usb, usb_endpoint_num(bulk_out));
+	gdrm->bulk_len = max_buffer_size;
+
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4) {
+		gdrm->lz4_comp_mem = devm_kmalloc(dev, LZ4_MEM_COMPRESS, GFP_KERNEL);
+		if (!gdrm->lz4_comp_mem)
+			return -ENOMEM;
+
+		gdrm->compress_buf = vmalloc(gdrm->bulk_len);
+		if (!gdrm->compress_buf)
+			return -ENOMEM;
+	}
+
+	drm->mode_config.min_width = le32_to_cpu(desc.dwMinWidth);
+	drm->mode_config.max_width = le32_to_cpu(desc.dwMaxWidth);
+	drm->mode_config.min_height = le32_to_cpu(desc.dwMinHeight);
+	drm->mode_config.max_height = le32_to_cpu(desc.dwMaxHeight);
+
+	formats_dev = devm_kmalloc_array(dev, desc.bNumFormats, sizeof(u32), GFP_KERNEL);
+	/* Add room for emulated XRGB8888 */
+	formats = devm_kmalloc_array(dev, desc.bNumFormats + 1, sizeof(u32), GFP_KERNEL);
+	if (!formats_dev || !formats)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_read32(gdrm, GUD_DRM_USB_REQ_GET_FORMATS, formats_dev, desc.bNumFormats);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < desc.bNumFormats; i++) {
+		const struct drm_format_info *fmt_info;
+		u32 format = formats_dev[i];
+
+		if (format == GUD_DRM_FORMAT_R1) {
+			fmt_info = &gud_drm_format_r1;
+		} else {
+			/* This will trigger a WARN for unknown formats... */
+			fmt_info = drm_format_info(format);
+			if (!fmt_info) {
+				drm_dbg(drm, "Unknown format: 0x%x\n", format);
+				continue;
+			}
+		}
+
+		switch (format) {
+		case DRM_FORMAT_XRGB8888:
+			fallthrough;
+		case DRM_FORMAT_ARGB8888:
+			rgb8888_supported = true;
+			break;
+		case DRM_FORMAT_RGB888:
+			fallthrough;
+		case DRM_FORMAT_BGR888:
+			drm_dbg(drm, "24-bit formats are not supported.\n");
+			continue;
+		case DRM_FORMAT_RGB565:
+			rgb565_supported = true;
+			if (!xrgb8888_emulation_format)
+				xrgb8888_emulation_format = fmt_info;
+			break;
+		case GUD_DRM_FORMAT_R1:
+			if (!xrgb8888_emulation_format)
+				xrgb8888_emulation_format = fmt_info;
+			/* Internal, not for userspace */
+			continue;
+		}
+
+		formats[num_formats++] = format;
+	}
+
+	if (!num_formats && !xrgb8888_emulation_format) {
+		dev_err(dev, "No supported formats found\n");
+		return -ENOENT;
+	}
+
+	/* Prefer speed over color depth */
+	if (rgb565_supported)
+		drm->mode_config.preferred_depth = 16;
+
+	if (!rgb8888_supported && xrgb8888_emulation_format) {
+		gdrm->xrgb8888_emulation_format = xrgb8888_emulation_format;
+		formats[num_formats++] = DRM_FORMAT_XRGB8888;
+	}
+
+	ret = drm_simple_display_pipe_init(drm, &gdrm->pipe, &gud_drm_pipe_funcs,
+					   formats, num_formats,
+					   gud_drm_pipe_modifiers, NULL);
+	if (ret)
+		return ret;
+
+	devm_kfree(dev, formats);
+	devm_kfree(dev, formats_dev);
+
+	ret = gud_drm_get_properties(gdrm, desc.bNumProperties);
+	if (ret)
+		return ret;
+
+	drm_plane_enable_fb_damage_clips(&gdrm->pipe.plane);
+
+	for (i = 0; i < num_connectors; i++) {
+		ret = gud_drm_connector_create(gdrm, i);
+		if (ret)
+			return ret;
+	}
+
+	drm_mode_config_reset(drm);
+
+	usb_set_intfdata(interface, gdrm);
+
+	ret = drm_dev_register(drm, 0);
+	if (ret)
+		return ret;
+
+	drm_kms_helper_poll_init(drm);
+
+	drm_fbdev_generic_setup(drm, 0);
+
+	return 0;
+}
+
+static void gud_drm_disconnect(struct usb_interface *interface)
+{
+	struct gud_drm_device *gdrm = usb_get_intfdata(interface);
+	struct drm_device *drm = &gdrm->drm;
+
+	drm_dbg(drm, "%s:\n", __func__);
+
+	drm_kms_helper_poll_fini(drm);
+	drm_dev_unplug(drm);
+	drm_atomic_helper_shutdown(drm);
+}
+
+static int gud_drm_suspend(struct usb_interface *interface, pm_message_t message)
+{
+	struct gud_drm_device *gdrm = usb_get_intfdata(interface);
+
+	return drm_mode_config_helper_suspend(&gdrm->drm);
+}
+
+static int gud_drm_resume(struct usb_interface *interface)
+{
+	struct gud_drm_device *gdrm = usb_get_intfdata(interface);
+
+	drm_mode_config_helper_resume(&gdrm->drm);
+
+	return 0;
+}
+
+static const struct usb_device_id gud_drm_table[] = {
+	/*
+	 * FIXME:
+	 * Apply for a proper pid: https://github.com/openmoko/openmoko-usb-oui
+	 */
+	{ USB_DEVICE_INTERFACE_CLASS(0x1d50, 0x6150, USB_CLASS_VENDOR_SPEC) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, gud_drm_table);
+
+static struct usb_driver gud_drm_usb_driver = {
+	.name		= "gud_drm",
+	.probe		= gud_drm_probe,
+	.disconnect	= gud_drm_disconnect,
+	.id_table	= gud_drm_table,
+	.suspend	= gud_drm_suspend,
+	.resume		= gud_drm_resume,
+	.reset_resume	= gud_drm_resume,
+};
+
+module_usb_driver(gud_drm_usb_driver);
+
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("Dual MIT/GPL");
diff --git a/drivers/gpu/drm/gud/gud_drm_internal.h b/drivers/gpu/drm/gud/gud_drm_internal.h
new file mode 100644
index 000000000000..30d86bb0389d
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_internal.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef __LINUX_GUD_DRM_INTERNAL_H
+#define __LINUX_GUD_DRM_INTERNAL_H
+
+#include <linux/workqueue.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+
+#include <drm/drm_simple_kms_helper.h>
+
+struct gud_drm_device {
+	struct drm_device drm;
+	struct drm_simple_display_pipe pipe;
+	struct work_struct work;
+	struct usb_device *usb;
+	u8 ifnum;
+	const struct drm_format_info *xrgb8888_emulation_format;
+
+	u16 *properties;
+	unsigned int num_properties;
+
+	unsigned int bulk_pipe;
+	void *bulk_buf;
+	size_t bulk_len;
+
+	u8 compression;
+	void *lz4_comp_mem;
+	void *compress_buf;
+
+	u64 stats_length;
+	u64 stats_actual_length;
+	unsigned int stats_num_errors;
+
+	struct mutex ctrl_lock; /* Serialize req and status transfers */
+	void *ctrl_msg_buf;
+	void *status_buf;
+
+	struct mutex damage_lock; /* Protects the following members: */
+	struct drm_framebuffer *fb;
+	struct drm_rect damage;
+};
+
+static inline struct gud_drm_device *to_gud_drm_device(struct drm_device *drm)
+{
+	return container_of(drm, struct gud_drm_device, drm);
+}
+
+int gud_drm_usb_get(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len);
+int gud_drm_usb_set(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len);
+int gud_drm_usb_write8(struct gud_drm_device *gdrm, u8 request, u8 val);
+
+void gud_drm_clear_damage(struct gud_drm_device *gdrm);
+void gud_drm_work(struct work_struct *work);
+int gud_drm_pipe_check(struct drm_simple_display_pipe *pipe,
+		       struct drm_plane_state *new_plane_state,
+		       struct drm_crtc_state *new_crtc_state);
+void gud_drm_pipe_update(struct drm_simple_display_pipe *pipe,
+			 struct drm_plane_state *old_state);
+
+int gud_drm_connector_fill_properties(struct drm_connector *connector,
+				      struct drm_connector_state *connector_state,
+				      struct gud_drm_property *properties);
+int gud_drm_connector_create(struct gud_drm_device *gdrm, unsigned int index);
+
+#endif
diff --git a/drivers/gpu/drm/gud/gud_drm_pipe.c b/drivers/gpu/drm/gud/gud_drm_pipe.c
new file mode 100644
index 000000000000..95023f465dcb
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_pipe.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/lz4.h>
+#include <linux/usb.h>
+#include <linux/workqueue.h>
+
+#include <drm/drm_atomic.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_print.h>
+#include <drm/drm_rect.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+static bool gud_drm_is_big_endian(void)
+{
+#if defined(__BIG_ENDIAN)
+	return true;
+#else
+	return false;
+#endif
+}
+
+static size_t gud_drm_xrgb8888_to_r124(u8 *dst, const struct drm_format_info *format,
+				       void *src, struct drm_framebuffer *fb,
+				       struct drm_rect *rect)
+{
+	unsigned int block_width = drm_format_info_block_width(format, 0);
+	unsigned int bits_per_pixel = 8 / block_width;
+	unsigned int x, y, width, height;
+	u8 *p, *block = dst; /* Assign to silence compiler warning */
+	size_t len;
+	void *buf;
+
+	WARN_ON_ONCE(format->char_per_block[0] != 1);
+
+	/* Start on a byte boundary */
+	rect->x1 = ALIGN_DOWN(rect->x1, block_width);
+	width = drm_rect_width(rect);
+	height = drm_rect_height(rect);
+	len = drm_format_info_min_pitch(format, 0, width) * height;
+
+	buf = kmalloc(width * height, GFP_KERNEL);
+	if (!buf)
+		return len; /* To keep logic simple, just transmit garbage */
+
+	drm_fb_xrgb8888_to_gray8(buf, src, fb, rect);
+
+	p = buf;
+	for (y = 0; y < drm_rect_height(rect); y++) {
+		for (x = 0; x < drm_rect_width(rect); x++) {
+			if (!(x % block_width)) {
+				block = dst++;
+				*block = 0;
+			}
+
+			*block <<= bits_per_pixel;
+			*block |= (*p++) >> (8 - bits_per_pixel);
+		}
+	}
+
+	kfree(buf);
+
+	return len;
+}
+
+static int gud_drm_fb_flush(struct gud_drm_device *gdrm, struct drm_framebuffer *fb,
+			    const struct drm_format_info *format, struct drm_rect *rect)
+{
+	struct dma_buf_attachment *import_attach = fb->obj[0]->import_attach;
+	struct gud_drm_req_set_buffer req;
+	size_t trlen, len;
+	int actual_length;
+	void *vaddr, *buf;
+	int ret = 0;
+
+	drm_dbg(&gdrm->drm, "Flushing [FB:%d] " DRM_RECT_FMT " imported=%s\n",
+		fb->base.id, DRM_RECT_ARG(rect), import_attach ? "yes" : "no");
+
+	len = drm_format_info_min_pitch(format, 0, drm_rect_width(rect)) * drm_rect_height(rect);
+	if (len > gdrm->bulk_len)
+		return -E2BIG;
+
+	vaddr = drm_gem_shmem_vmap(fb->obj[0]);
+	if (!vaddr)
+		return -ENOMEM;
+
+	if (import_attach) {
+		ret = dma_buf_begin_cpu_access(import_attach->dmabuf, DMA_FROM_DEVICE);
+		if (ret)
+			goto vunmap;
+	}
+
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4)
+		buf = gdrm->compress_buf;
+	else
+		buf = gdrm->bulk_buf;
+
+	/*
+	 * Imported buffers are assumed to be write-combined and thus uncached
+	 * with slow reads (at least on ARM).
+	 */
+	if (format != fb->format) {
+		if (format->format == GUD_DRM_FORMAT_R1)
+			len = gud_drm_xrgb8888_to_r124(buf, format, vaddr, fb, rect);
+		else if (format->format == DRM_FORMAT_RGB565)
+			drm_fb_xrgb8888_to_rgb565(buf, vaddr, fb, rect, gud_drm_is_big_endian());
+	} else if (gud_drm_is_big_endian() && format->cpp[0] > 1) {
+		drm_fb_swab(buf, vaddr, fb, rect, !import_attach);
+	} else if (!import_attach && gdrm->compression && len == fb->height * fb->pitches[0]) {
+		/* can compress directly from the framebuffer */
+		buf = vaddr;
+	} else {
+		drm_fb_memcpy(buf, vaddr, fb, rect);
+	}
+
+	req.x = cpu_to_le32(rect->x1);
+	req.y = cpu_to_le32(rect->y1);
+	req.width = cpu_to_le32(drm_rect_width(rect));
+	req.height = cpu_to_le32(drm_rect_height(rect));
+	req.length = cpu_to_le32(len);
+
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4) {
+		ret = LZ4_compress_default(buf, gdrm->bulk_buf, len, len, gdrm->lz4_comp_mem);
+		if (ret > 0)
+			req.compression = GUD_DRM_COMPRESSION_LZ4;
+	}
+
+	trlen = len;
+
+	if (ret > 0) {
+		req.compressed_length = cpu_to_le32(ret);
+		trlen = ret;
+	} else if (buf == gdrm->compress_buf) {
+		/*
+		 * Compression failed (buffer didn't compress well).
+		 * compress_buf is vmalloc'ed so we need to copy.
+		 */
+		memcpy(gdrm->bulk_buf, gdrm->compress_buf, len);
+	}
+
+	if (import_attach)
+		dma_buf_end_cpu_access(import_attach->dmabuf, DMA_FROM_DEVICE);
+
+	gdrm->stats_length += len;
+	/* Did it wrap around? */
+	if (gdrm->stats_length <= len && gdrm->stats_actual_length) {
+		gdrm->stats_length = len;
+		gdrm->stats_actual_length = 0;
+	}
+	gdrm->stats_actual_length += trlen;
+
+	/*
+	 * This will wait if decompress/copy from the previous flush is still in
+	 * process on the gadget side.
+	 */
+	ret = gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_BUFFER, 0, &req, sizeof(req));
+	if (ret)
+		goto vunmap;
+
+	ret = usb_bulk_msg(gdrm->usb, gdrm->bulk_pipe, gdrm->bulk_buf, trlen,
+			   &actual_length, msecs_to_jiffies(3000));
+	if (!ret && trlen != actual_length)
+		ret = -EIO;
+	if (ret)
+		gdrm->stats_num_errors++;
+vunmap:
+	drm_gem_shmem_vunmap(fb->obj[0], vaddr);
+
+	return ret;
+}
+
+void gud_drm_clear_damage(struct gud_drm_device *gdrm)
+{
+	gdrm->damage.x1 = INT_MAX;
+	gdrm->damage.y1 = INT_MAX;
+	gdrm->damage.x2 = 0;
+	gdrm->damage.y2 = 0;
+}
+
+void gud_drm_work(struct work_struct *work)
+{
+	struct gud_drm_device *gdrm = container_of(work, struct gud_drm_device, work);
+	const struct drm_format_info *format;
+	struct drm_framebuffer *fb;
+	struct drm_rect damage;
+	unsigned int i, lines;
+	int idx, ret = 0;
+	size_t pitch;
+
+	if (!drm_dev_enter(&gdrm->drm, &idx))
+		return;
+
+	mutex_lock(&gdrm->damage_lock);
+	fb = gdrm->fb;
+	gdrm->fb = NULL;
+	damage = gdrm->damage;
+	gud_drm_clear_damage(gdrm);
+	mutex_unlock(&gdrm->damage_lock);
+
+	if (!fb)
+		goto out;
+
+	format = fb->format;
+	if (format->format == DRM_FORMAT_XRGB8888 && gdrm->xrgb8888_emulation_format)
+		format = gdrm->xrgb8888_emulation_format;
+
+	/* Split update if it's too big */
+	pitch = drm_format_info_min_pitch(format, 0, drm_rect_width(&damage));
+	lines = drm_rect_height(&damage);
+
+	if (gdrm->bulk_len < lines * pitch)
+		lines = gdrm->bulk_len / pitch;
+
+	for (i = 0; i < DIV_ROUND_UP(drm_rect_height(&damage), lines); i++) {
+		struct drm_rect rect = damage;
+
+		rect.y1 += i * lines;
+		rect.y2 = min_t(u32, rect.y1 + lines, damage.y2);
+
+		ret = gud_drm_fb_flush(gdrm, fb, format, &rect);
+		if (ret &&
+		    (ret != -ENODEV && ret != -ECONNRESET && ret != -ESHUTDOWN && ret != -EPROTO))
+			dev_err_once(fb->dev->dev, "Failed to flush framebuffer: error=%d\n", ret);
+	}
+
+	drm_framebuffer_put(fb);
+out:
+	drm_dev_exit(idx);
+}
+
+static void gud_drm_fb_queue_damage(struct gud_drm_device *gdrm,
+				    struct drm_framebuffer *fb,
+				    struct drm_rect *damage)
+{
+	struct drm_framebuffer *old_fb = NULL;
+
+	mutex_lock(&gdrm->damage_lock);
+
+	if (fb != gdrm->fb) {
+		old_fb = gdrm->fb;
+		drm_framebuffer_get(fb);
+		gdrm->fb = fb;
+	}
+
+	gdrm->damage.x1 = min(gdrm->damage.x1, damage->x1);
+	gdrm->damage.y1 = min(gdrm->damage.y1, damage->y1);
+	gdrm->damage.x2 = max(gdrm->damage.x2, damage->x2);
+	gdrm->damage.y2 = max(gdrm->damage.y2, damage->y2);
+
+	mutex_unlock(&gdrm->damage_lock);
+
+	queue_work(system_long_wq, &gdrm->work);
+
+	if (old_fb)
+		drm_framebuffer_put(old_fb);
+}
+
+int gud_drm_pipe_check(struct drm_simple_display_pipe *pipe,
+		       struct drm_plane_state *new_plane_state,
+		       struct drm_crtc_state *new_crtc_state)
+{
+	struct gud_drm_device *gdrm = to_gud_drm_device(pipe->crtc.dev);
+	struct drm_plane_state *old_plane_state = pipe->plane.state;
+	const struct drm_display_mode *mode = &new_crtc_state->mode;
+	struct drm_atomic_state *state = new_plane_state->state;
+	struct drm_framebuffer *old_fb = old_plane_state->fb;
+	struct drm_connector_state *connector_state = NULL;
+	struct drm_framebuffer *fb = new_plane_state->fb;
+	const struct drm_format_info *format = fb->format;
+	struct gud_drm_req_set_state *req;
+	struct drm_connector *connector;
+	int idx, ret, num_properties;
+	unsigned int i;
+	size_t len;
+
+	if (WARN_ON_ONCE(!fb))
+		return -EINVAL;
+
+	if (old_plane_state->rotation != new_plane_state->rotation)
+		new_crtc_state->mode_changed = true;
+
+	if (old_fb && old_fb->format != format)
+		new_crtc_state->mode_changed = true;
+
+	if (!new_crtc_state->mode_changed && !new_crtc_state->connectors_changed)
+		return 0;
+
+	/* Only one connector is supported */
+	if (hweight32(new_crtc_state->connector_mask) != 1)
+		return -EINVAL;
+
+	if (format->format == DRM_FORMAT_XRGB8888 && gdrm->xrgb8888_emulation_format)
+		format = gdrm->xrgb8888_emulation_format;
+
+	for_each_new_connector_in_state(state, connector, connector_state, i)
+		break;
+
+	if (!connector_state) {
+		struct drm_connector_list_iter conn_iter;
+
+		/* We always send the full state to the device, so get the connector state */
+
+		drm_connector_list_iter_begin(pipe->crtc.dev, &conn_iter);
+		drm_for_each_connector_iter(connector, &conn_iter) {
+			if (new_crtc_state->connector_mask & drm_connector_mask(connector))
+				break;
+		}
+		drm_connector_list_iter_end(&conn_iter);
+
+		if (WARN_ON_ONCE(!connector))
+			return -ENOENT;
+
+		connector_state = drm_atomic_get_connector_state(state, connector);
+		if (IS_ERR(connector_state))
+			return PTR_ERR(connector_state);
+	}
+
+	num_properties = gud_drm_connector_fill_properties(connector, NULL, NULL);
+	if (num_properties < 0)
+		return num_properties;
+
+	num_properties += gdrm->num_properties;
+
+	len = struct_size(req, properties, num_properties);
+	req = kzalloc(len, GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	gud_drm_from_display_mode(&req->mode, mode);
+
+	req->format = cpu_to_le32(format->format);
+	req->connector = drm_connector_index(connector);
+	req->num_properties = num_properties;
+
+	num_properties = gud_drm_connector_fill_properties(connector, connector_state,
+							   req->properties);
+
+	for (i = 0; i < gdrm->num_properties; i++) {
+		u16 prop = gdrm->properties[i];
+		u64 val;
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_ROTATION:
+			val = new_plane_state->rotation;
+			break;
+		default:
+			WARN_ON_ONCE(1);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		req->properties[num_properties + i].prop = cpu_to_le16(prop);
+		req->properties[num_properties + i].val = cpu_to_le64(val);
+	}
+
+	if (!drm_dev_enter(fb->dev, &idx)) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	ret = gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_STATE_CHECK, 0, req, len);
+
+	drm_dev_exit(idx);
+out:
+	kfree(req);
+
+	return ret;
+}
+
+void gud_drm_pipe_update(struct drm_simple_display_pipe *pipe,
+			 struct drm_plane_state *old_state)
+{
+	struct drm_device *drm = pipe->crtc.dev;
+	struct gud_drm_device *gdrm = to_gud_drm_device(drm);
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_framebuffer *fb = state->fb;
+	struct drm_crtc *crtc = &pipe->crtc;
+	struct drm_rect damage;
+	int idx;
+
+	if (!drm_dev_enter(drm, &idx))
+		return;
+
+	if (!old_state->fb)
+		gud_drm_usb_write8(gdrm, GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE, 1);
+
+	if (fb && (crtc->state->mode_changed || crtc->state->connectors_changed))
+		gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_STATE_COMMIT, 0, NULL, 0);
+
+	if (crtc->state->active_changed)
+		gud_drm_usb_write8(gdrm, GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE, crtc->state->active);
+
+	if (drm_atomic_helper_damage_merged(old_state, state, &damage))
+		gud_drm_fb_queue_damage(gdrm, fb, &damage);
+
+	if (!fb) {
+		cancel_work_sync(&gdrm->work);
+
+		mutex_lock(&gdrm->damage_lock);
+		if (gdrm->fb) {
+			drm_framebuffer_put(gdrm->fb);
+			gdrm->fb = NULL;
+		}
+		gud_drm_clear_damage(gdrm);
+		mutex_unlock(&gdrm->damage_lock);
+
+		gud_drm_usb_write8(gdrm, GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE, 0);
+	}
+
+	drm_dev_exit(idx);
+}
diff --git a/include/drm/gud_drm.h b/include/drm/gud_drm.h
new file mode 100644
index 000000000000..36d35bc7cff2
--- /dev/null
+++ b/include/drm/gud_drm.h
@@ -0,0 +1,364 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#ifndef __LINUX_GUD_DRM_H
+#define __LINUX_GUD_DRM_H
+
+#include <drm/drm_modes.h>
+#include <linux/types.h>
+#include <uapi/drm/drm_fourcc.h>
+#include <uapi/linux/usb/ch9.h>
+
+/*
+ * Maximum size of a control message, fits 120 display modes.
+ * If this needs to increase, the IN side in f_gud_drm_setup()
+ * needs fixing.
+ */
+#define GUD_DRM_MAX_TRANSFER_SIZE	SZ_4K
+
+#define GUD_DRM_USB_DT_DISPLAY		(USB_TYPE_VENDOR | 0x4)
+
+/*
+ * struct gud_drm_display_descriptor - Display descriptor
+ * @bLength: Size of descriptor in bytes
+ * @bDescriptorType: DescriptorType (GUD_DRM_USB_DT_DISPLAY)
+ * @bVersion: Protocol version
+ * @bMaxBufferSizeOrder: Maximum buffer size the device can handle as log2
+ * @bmFlags: Currently unused, should be set to zero
+ * @bCompression: Supported compression types
+ * @dwMinWidth: Minimum pixel width the controller can handle
+ * @dwMaxWidth: Maximum width
+ * @dwMinHeight: Minimum height
+ * @dwMaxHeight: Maximum height
+ * @bNumFormats: Number of supported pixel formats
+ * @bNumProperties: Number of properties that are not connector porperties
+ * @bNumConnectors: Number of connectors
+ *
+ * Devices that have only one display mode will have dwMinWidth == dwMaxWidth
+ * and dwMinHeight == dwMaxHeight.
+ *
+ */
+struct gud_drm_display_descriptor {
+	__u8 bLength;
+	__u8 bDescriptorType;
+
+	__u8 bVersion;
+	__u8 bMaxBufferSizeOrder;
+	__le32 bmFlags;
+
+	__u8 bCompression;
+#define GUD_DRM_COMPRESSION_LZ4		BIT(0)
+
+	__le32 dwMinWidth;
+	__le32 dwMaxWidth;
+	__le32 dwMinHeight;
+	__le32 dwMaxHeight;
+
+	__u8 bNumFormats;
+	__u8 bNumProperties;
+	__u8 bNumConnectors;
+} __packed;
+
+/*
+ * struct gud_drm_req_get_status - Status request
+ * @flags: Flags
+ * @errno: Linux errno value
+ *
+ * The host keeps polling for status as long as the GUD_DRM_STATUS_PENDING flag
+ * is set (or until timeout). Requested using: USB_REQ_GET_STATUS.
+ */
+struct gud_drm_req_get_status {
+	__u8 flags;
+#define GUD_DRM_STATUS_PENDING	BIT(0)
+	__u8 errno;
+} __packed;
+
+/*
+ * struct gud_drm_property - Property
+ * @prop: Property
+ * @val: Value
+ */
+struct gud_drm_property {
+	__le16 prop;
+	__le64 val;
+} __packed;
+
+/* See &drm_display_mode for the meaning of these fields */
+struct gud_drm_display_mode {
+	__le32 clock;
+	__le16 hdisplay;
+	__le16 hsync_start;
+	__le16 hsync_end;
+	__le16 htotal;
+	__le16 hskew;
+	__le16 vdisplay;
+	__le16 vsync_start;
+	__le16 vsync_end;
+	__le16 vtotal;
+	__le16 vscan;
+	__le32 vrefresh;
+	__le32 flags;
+	__u8 type;
+} __packed;
+
+/*
+ * struct gud_drm_req_get_connector - Connector descriptor
+ * @connector_type: Connector type (DRM_MODE_CONNECTOR_*)
+ * @flags: Flags
+ * @num_properties: Number of supported properties
+ */
+struct gud_drm_req_get_connector {
+	__u8 connector_type;
+
+	__le32 flags;
+#define GUD_DRM_CONNECTOR_FLAGS_POLL	BIT(0)
+
+	__u8 num_properties;
+} __packed;
+
+/*
+ * struct gud_drm_req_get_connector_status - Connector status
+ * @status: Status, see &drm_connector_status
+ * @num_modes: Number of available display modes
+ * @modes_array_checksum: CRC-CCITT checksum of the display mode array in little endian format
+ * @edid_len: Length of EDID data
+ * @edid_checksum: CRC-CCITT checksum of EDID data
+ *
+ * If both @num_modes and @edid_len are zero, connector status is set to
+ * disconnected. If @num_modes is zero, edid is used to create display modes.
+ * If both are set, edid is just passed on to userspace in the EDID connector
+ * property.
+ *
+ * Display modes and EDID are only requested if number/length or crc differs.
+ */
+struct gud_drm_req_get_connector_status {
+	__u8 status;
+#define GUD_DRM_CONNECTOR_STATUS_MASK		0xf /* Only 2 bits are currently used for status */
+#define GUD_DRM_CONNECTOR_STATUS_CHANGED	BIT(7)
+	__u16 num_modes;
+	__u16 edid_len;
+} __packed;
+
+/*
+ * struct gud_drm_req_set_buffer - Set buffer transfer info
+ * @x: X position of rectangle
+ * @y: Y position
+ * @width: Pixel width of rectangle
+ * @height: Pixel height
+ * @length: Buffer length in bytes
+ * @compression: Transfer compression
+ * @compressed_length: Compressed buffer length
+ *
+ * @x, @y, @width and @height specifies the rectangle where the buffer should be
+ * placed inside the framebuffer.
+ */
+struct gud_drm_req_set_buffer {
+	__le32 x;
+	__le32 y;
+	__le32 width;
+	__le32 height;
+
+	__le32 length;
+	__u8 compression;
+	__le32 compressed_length;
+} __packed;
+
+/*
+ * struct gud_drm_req_set_state - Set display state
+ * @mode: Display mode
+ * @format: Pixel format
+ * @connector: Connector index
+ * @num_properties: Number of properties in the state
+ * @properties: Array of properties
+ *
+ * The entire state is transferred each time there's a change.
+ */
+struct gud_drm_req_set_state {
+	struct gud_drm_display_mode mode;
+	__le32 format;
+	__u8 connector;
+	__u8 num_properties;
+	struct gud_drm_property properties[];
+} __packed;
+
+/*
+ * Internal monochrome transfer format presented to userspace as XRGB8888.
+ * Pixel lines are byte aligned.
+ */
+#define GUD_DRM_FORMAT_R1	fourcc_code('R', '1', ' ', ' ')
+
+/* List of supported connector properties: */
+
+/* TV related properties, see &drm_connector and &drm_tv_connector_state */
+#define GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR		1
+#define GUD_DRM_PROPERTY_TV_LEFT_MARGIN			2
+#define GUD_DRM_PROPERTY_TV_RIGHT_MARGIN		3
+#define GUD_DRM_PROPERTY_TV_TOP_MARGIN			4
+#define GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN		5
+/* Number of modes are placed at _SHIFT in val on retrieval */
+#define GUD_DRM_PROPERTY_TV_MODE			6
+  #define GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT   16
+#define GUD_DRM_PROPERTY_TV_BRIGHTNESS			7
+#define GUD_DRM_PROPERTY_TV_CONTRAST			8
+#define GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION		9
+#define GUD_DRM_PROPERTY_TV_OVERSCAN			10
+#define GUD_DRM_PROPERTY_TV_SATURATION			11
+#define GUD_DRM_PROPERTY_TV_HUE				12
+
+/*
+ * Backlight brightness is in the range 0-100 inclusive. The value represents
+ * the human perceptual brightness and not a linear PWM value. 0 is minimum
+ * brightness which should not turn the backlight completely off. The DPMS
+ * connector property should be used to control power which will trigger a
+ * GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE request.
+ *
+ * This is not a real DRM property, but rather a fake one used for the backlight
+ * device. See drm_backlight_register() for more details.
+ */
+#define GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS		13
+
+/* List of supported properties that are not connector propeties: */
+
+/*
+ * Plane rotation. Should return the supported bitmask on
+ * GUD_DRM_USB_REQ_GET_PROPERTIES, see drm_plane_create_rotation_property().
+ */
+#define GUD_DRM_PROPERTY_ROTATION			50
+
+/* USB Control requests: */
+
+/*
+ * If the host driver doesn't support the device protocol version it will send
+ * its version (u8). If the device isn't backwards compatible or doesn't support
+ * the host version it shall halt the transfer. There is no status request
+ * issued if this request fails/halts.
+ */
+#define GUD_DRM_USB_REQ_SET_VERSION			0x30
+
+/* Get supported pixel formats as an array of fourcc codes. See include/uapi/drm/drm_fourcc.h */
+#define GUD_DRM_USB_REQ_GET_FORMATS			0x40
+
+/* Get supported properties that are not connector propeties as a &gud_drm_property array */
+#define GUD_DRM_USB_REQ_GET_PROPERTIES			0x41
+
+/* Get connector descriptor */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR			0x50
+
+/* Get properties supported by the connector as a &gud_drm_property array */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_PROPERTIES	0x51
+
+/*
+ * Issued when there's a tv.mode property present.
+ * Gets an array of tv.mode enum names each entry of length DRM_PROP_NAME_LEN.
+ */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_TV_MODE_VALUES	0x52
+
+/* When userspace checks status, this is issued first, not used for poll requests. */
+#define GUD_DRM_USB_REQ_SET_CONNECTOR_FORCE_DETECT	0x53
+
+/* Get connector status as &gud_drm_req_get_connector_status. */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_STATUS		0x54
+
+/* Get &gud_drm_display_mode array of supported display modes */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_MODES		0x55
+
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_EDID		0x56
+
+/* Set buffer properties before bulk transfer as &gud_drm_req_set_buffer */
+#define GUD_DRM_USB_REQ_SET_BUFFER			0x60
+
+/* Check display configuration as &gud_drm_req_set_state */
+#define GUD_DRM_USB_REQ_SET_STATE_CHECK			0x61
+
+/* Apply the prevoius _STATE_CHECK configuration */
+#define GUD_DRM_USB_REQ_SET_STATE_COMMIT		0x62
+
+ /* Enable/disable the display controller, value is u8 0/1 */
+#define GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE		0x63
+
+/* Enable/disable display/output (DPMS), value is u8 0/1 */
+#define GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE		0x64
+
+static inline void gud_drm_from_display_mode(struct gud_drm_display_mode *dst,
+					     const struct drm_display_mode *src)
+{
+	u32 flags = src->flags;
+
+	switch (src->picture_aspect_ratio) {
+	case HDMI_PICTURE_ASPECT_4_3:
+		flags |= DRM_MODE_FLAG_PIC_AR_4_3;
+		break;
+	case HDMI_PICTURE_ASPECT_16_9:
+		flags |= DRM_MODE_FLAG_PIC_AR_16_9;
+		break;
+	case HDMI_PICTURE_ASPECT_64_27:
+		flags |= DRM_MODE_FLAG_PIC_AR_64_27;
+		break;
+	case HDMI_PICTURE_ASPECT_256_135:
+		flags |= DRM_MODE_FLAG_PIC_AR_256_135;
+		break;
+	default:
+		flags |= DRM_MODE_FLAG_PIC_AR_NONE;
+		break;
+	}
+
+	dst->clock = cpu_to_le32(src->clock);
+	dst->hdisplay = cpu_to_le16(src->hdisplay);
+	dst->hsync_start = cpu_to_le16(src->hsync_start);
+	dst->hsync_end = cpu_to_le16(src->hsync_end);
+	dst->htotal = cpu_to_le16(src->htotal);
+	dst->hskew = cpu_to_le16(src->hskew);
+	dst->vdisplay = cpu_to_le16(src->vdisplay);
+	dst->vsync_start = cpu_to_le16(src->vsync_start);
+	dst->vsync_end = cpu_to_le16(src->vsync_end);
+	dst->vtotal = cpu_to_le16(src->vtotal);
+	dst->vscan = cpu_to_le16(src->vscan);
+	dst->vrefresh = cpu_to_le32(src->vrefresh);
+	dst->flags = cpu_to_le32(flags);
+	dst->type = src->type;
+}
+
+static inline void gud_drm_to_display_mode(struct drm_display_mode *dst,
+					   const struct gud_drm_display_mode *src)
+{
+	u32 flags = le32_to_cpu(src->flags);
+
+	dst->clock = le32_to_cpu(src->clock);
+	dst->hdisplay = le16_to_cpu(src->hdisplay);
+	dst->hsync_start = le16_to_cpu(src->hsync_start);
+	dst->hsync_end = le16_to_cpu(src->hsync_end);
+	dst->htotal = le16_to_cpu(src->htotal);
+	dst->hskew = le16_to_cpu(src->hskew);
+	dst->vdisplay = le16_to_cpu(src->vdisplay);
+	dst->vsync_start = le16_to_cpu(src->vsync_start);
+	dst->vsync_end = le16_to_cpu(src->vsync_end);
+	dst->vtotal = le16_to_cpu(src->vtotal);
+	dst->vscan = le16_to_cpu(src->vscan);
+	dst->vrefresh = le32_to_cpu(src->vrefresh);
+	dst->flags = flags & ~DRM_MODE_FLAG_PIC_AR_MASK;
+	dst->type = src->type;
+
+	switch (flags & DRM_MODE_FLAG_PIC_AR_MASK) {
+	case DRM_MODE_FLAG_PIC_AR_4_3:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3;
+		break;
+	case DRM_MODE_FLAG_PIC_AR_16_9:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9;
+		break;
+	case DRM_MODE_FLAG_PIC_AR_64_27:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_64_27;
+		break;
+	case DRM_MODE_FLAG_PIC_AR_256_135:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_256_135;
+		break;
+	default:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
+		break;
+	}
+
+	drm_mode_set_name(dst);
+}
+
+#endif
-- 
2.23.0

[PATCH v2 08/10] drm: Add Generic USB Display driver

[Noralf Trønnes]

This adds a generic USB display driver with the intention that it can be
used with future USB interfaced low end displays/adapters. The Linux
gadget device driver will serve as the canonical device implementation.

The following DRM properties are supported:
- Plane rotation
- Connector TV properties

There is also support for backlight brightness exposed as a backlight
device.

Display modes can be made available to the host driver either as DRM
display modes or through EDID. If both are present, EDID is just passed
on to userspace.

Performance is preferred over color depth, so if the device supports
RGB565, DRM_CAP_DUMB_PREFERRED_DEPTH will return 16.

If the device transfer buffer can't fit an uncompressed framebuffer
update, the update is split up into parts that do fit.

Optimal user experience is achieved by providing damage reports either by
setting FB_DAMAGE_CLIPS on pageflips or calling DRM_IOCTL_MODE_DIRTYFB.

LZ4 compression is used if the device supports it.

The driver supports a one bit monochrome transfer format: R1. This is not
implemented in the gadget driver. It is added in preparation for future
monochrome e-ink displays.

The driver is MIT licensed to smooth the path for any BSD port of the
driver.

v2:
- Use devm_drm_dev_alloc() and drmm_mode_config_init()
- drm_fbdev_generic_setup: Use preferred_bpp=0, 16 was a copy paste error
- The drm_backlight_helper is dropped, copy in the code
- Support protocol version backwards compatibility for device

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 MAINTAINERS                             |   8 +
 drivers/gpu/drm/Kconfig                 |   2 +
 drivers/gpu/drm/Makefile                |   1 +
 drivers/gpu/drm/gud/Kconfig             |  14 +
 drivers/gpu/drm/gud/Makefile            |   4 +
 drivers/gpu/drm/gud/gud_drm_connector.c | 724 ++++++++++++++++++++++++
 drivers/gpu/drm/gud/gud_drm_drv.c       | 641 +++++++++++++++++++++
 drivers/gpu/drm/gud/gud_drm_internal.h  |  66 +++
 drivers/gpu/drm/gud/gud_drm_pipe.c      | 423 ++++++++++++++
 include/drm/gud_drm.h                   | 364 ++++++++++++
 10 files changed, 2247 insertions(+)
 create mode 100644 drivers/gpu/drm/gud/Kconfig
 create mode 100644 drivers/gpu/drm/gud/Makefile
 create mode 100644 drivers/gpu/drm/gud/gud_drm_connector.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_drv.c
 create mode 100644 drivers/gpu/drm/gud/gud_drm_internal.h
 create mode 100644 drivers/gpu/drm/gud/gud_drm_pipe.c
 create mode 100644 include/drm/gud_drm.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 5fa9beacee86..7494a21ea41e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5291,6 +5291,14 @@ S:	Maintained
 F:	drivers/gpu/drm/panel/panel-feiyang-fy07024di26a30d.c
 F:	Documentation/devicetree/bindings/display/panel/feiyang,fy07024di26a30d.yaml
 
+DRM DRIVER FOR GENERIC USB DISPLAY
+M:	Noralf Trønnes <noralf@tronnes.org>
+S:	Maintained
+W:	https://github.com/notro/gud/wiki
+T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	drivers/gpu/drm/gud/
+F:	include/drm/gud_drm.h
+
 DRM DRIVER FOR GRAIN MEDIA GM12U320 PROJECTORS
 M:	Hans de Goede <hdegoede@redhat.com>
 S:	Maintained
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index 4bffa08f610a..33e63b68a82d 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -391,6 +391,8 @@ source "drivers/gpu/drm/mcde/Kconfig"
 
 source "drivers/gpu/drm/tidss/Kconfig"
 
+source "drivers/gpu/drm/gud/Kconfig"
+
 # Keep legacy drivers last
 
 menuconfig DRM_LEGACY
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index 53d8fa170143..41a87763f0e5 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -124,3 +124,4 @@ obj-$(CONFIG_DRM_PANFROST) += panfrost/
 obj-$(CONFIG_DRM_ASPEED_GFX) += aspeed/
 obj-$(CONFIG_DRM_MCDE) += mcde/
 obj-$(CONFIG_DRM_TIDSS) += tidss/
+obj-y			+= gud/
diff --git a/drivers/gpu/drm/gud/Kconfig b/drivers/gpu/drm/gud/Kconfig
new file mode 100644
index 000000000000..767f1c067ed9
--- /dev/null
+++ b/drivers/gpu/drm/gud/Kconfig
@@ -0,0 +1,14 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config DRM_GUD
+	tristate "Generic USB Display"
+	depends on DRM && USB
+	select LZ4_COMPRESS
+	select DRM_KMS_HELPER
+	select DRM_GEM_SHMEM_HELPER
+	select BACKLIGHT_CLASS_DEVICE
+	help
+	  This is a DRM display driver for Generic USB Displays or display
+	  adapters.
+
+	  If M is selected the module will be called gud_drm.
diff --git a/drivers/gpu/drm/gud/Makefile b/drivers/gpu/drm/gud/Makefile
new file mode 100644
index 000000000000..73ed7ef3da94
--- /dev/null
+++ b/drivers/gpu/drm/gud/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
+
+gud_drm-objs			:= gud_drm_drv.o gud_drm_pipe.o gud_drm_connector.o
+obj-$(CONFIG_DRM_GUD)		+= gud_drm.o
diff --git a/drivers/gpu/drm/gud/gud_drm_connector.c b/drivers/gpu/drm/gud/gud_drm_connector.c
new file mode 100644
index 000000000000..eba1665582f4
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_connector.c
@@ -0,0 +1,724 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/backlight.h>
+
+#include <drm/drm_atomic.h>
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_encoder.h>
+#include <drm/drm_file.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+struct gud_drm_connector {
+	struct drm_connector connector;
+	struct drm_encoder encoder;
+	struct backlight_device *backlight;
+
+	u32 flags;
+
+	/* Supported properties */
+	u16 *properties;
+	unsigned int num_properties;
+
+	/* Initial gadget tv state if applicable, applied on state reset */
+	struct drm_tv_connector_state initial_tv_state;
+
+	/*
+	 * Initial gadget backlight brightness if applicable, applied on state reset.
+	 * The value -ENODEV is used internally to signal no backlight.
+	 */
+	int initial_brightness;
+
+	/* Supported display modes in transfer format */
+	struct gud_drm_display_mode *modes;
+	unsigned int num_modes;
+
+	/* EDID */
+	void *edid;
+	size_t edid_len;
+};
+
+static inline struct gud_drm_connector *to_gud_drm_connector(struct drm_connector *connector)
+{
+	return container_of(connector, struct gud_drm_connector, connector);
+}
+
+static int gud_drm_connector_backlight_update_status(struct backlight_device *bd)
+{
+	struct drm_connector *connector = bl_get_data(bd);
+	struct drm_connector_state *connector_state;
+	struct drm_device *dev = connector->dev;
+	struct drm_modeset_acquire_ctx ctx;
+	struct drm_atomic_state *state;
+	int ret;
+
+	state = drm_atomic_state_alloc(dev);
+	if (!state)
+		return -ENOMEM;
+
+	drm_modeset_acquire_init(&ctx, 0);
+	state->acquire_ctx = &ctx;
+retry:
+	connector_state = drm_atomic_get_connector_state(state, connector);
+	if (IS_ERR(connector_state)) {
+		ret = PTR_ERR(connector_state);
+		goto out;
+	}
+
+	/* Reuse tv.brightness to avoid having to subclass */
+	connector_state->tv.brightness = bd->props.brightness;
+
+	ret = drm_atomic_commit(state);
+out:
+	if (ret == -EDEADLK) {
+		drm_atomic_state_clear(state);
+		drm_modeset_backoff(&ctx);
+		goto retry;
+	}
+
+	drm_atomic_state_put(state);
+
+	drm_modeset_drop_locks(&ctx);
+	drm_modeset_acquire_fini(&ctx);
+
+	return ret;
+}
+
+static int gud_drm_connector_backlight_get_brightness(struct backlight_device *bd)
+{
+	struct drm_connector *connector = bl_get_data(bd);
+	struct drm_device *dev = connector->dev;
+	int brightness;
+
+	drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
+	brightness = connector->state->tv.brightness;
+	drm_modeset_unlock(&dev->mode_config.connection_mutex);
+
+	return brightness;
+}
+
+static const struct backlight_ops gud_drm_connector_backlight_ops = {
+	.get_brightness = gud_drm_connector_backlight_get_brightness,
+	.update_status	= gud_drm_connector_backlight_update_status,
+};
+
+static int gud_drm_connector_backlight_register(struct gud_drm_connector *gconn)
+{
+	struct drm_connector *connector = &gconn->connector;
+	struct backlight_device *bd;
+	const char *name;
+	const struct backlight_properties props = {
+		.type = BACKLIGHT_RAW,
+		.scale = BACKLIGHT_SCALE_NON_LINEAR,
+		.max_brightness = 100,
+	};
+
+	name = kasprintf(GFP_KERNEL, "card%d-%s-backlight",
+			 connector->dev->primary->index, connector->name);
+	if (!name)
+		return -ENOMEM;
+
+	bd = backlight_device_register(name, connector->kdev, connector,
+				       &gud_drm_connector_backlight_ops, &props);
+	kfree(name);
+	if (IS_ERR(bd))
+		return PTR_ERR(bd);
+
+	gconn->backlight = bd;
+
+	return 0;
+}
+
+static void gud_drm_connector_modes_clear(struct gud_drm_connector *gconn)
+{
+	kfree(gconn->modes);
+	gconn->modes = NULL;
+	gconn->num_modes = 0;
+}
+
+static int gud_drm_connector_modes_get(struct gud_drm_connector *gconn, unsigned int num_modes)
+{
+	struct gud_drm_device *gdrm = to_gud_drm_device(gconn->connector.dev);
+	unsigned int index = gconn->connector.index;
+	int ret = 0;
+
+	if (!num_modes)
+		goto clear;
+
+	gud_drm_connector_modes_clear(gconn);
+
+	gconn->modes = kmalloc_array(num_modes, sizeof(*gconn->modes), GFP_KERNEL);
+	if (!gconn->modes)
+		return -ENOMEM;
+
+	gconn->num_modes = num_modes;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_MODES, index,
+			      gconn->modes, num_modes * sizeof(*gconn->modes));
+	if (ret)
+		goto clear;
+
+	return 0;
+clear:
+	gud_drm_connector_modes_clear(gconn);
+
+	return ret;
+}
+
+static void gud_drm_connector_edid_clear(struct gud_drm_connector *gconn)
+{
+	kfree(gconn->edid);
+	gconn->edid = NULL;
+	gconn->edid_len = 0;
+}
+
+static int gud_drm_connector_edid_get(struct gud_drm_connector *gconn, size_t len)
+{
+	struct gud_drm_device *gdrm = to_gud_drm_device(gconn->connector.dev);
+	unsigned int index = gconn->connector.index;
+	int ret = 0;
+
+	if (!len)
+		goto clear;
+
+	gud_drm_connector_edid_clear(gconn);
+
+	gconn->edid = kmalloc(len, GFP_KERNEL);
+	if (!gconn->edid)
+		return -ENOMEM;
+
+	gconn->edid_len = len;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_EDID, index, gconn->edid, len);
+	if (ret)
+		goto clear;
+
+	return 0;
+clear:
+	gud_drm_connector_edid_clear(gconn);
+
+	return ret;
+}
+
+static int gud_drm_connector_detect_safe(struct drm_connector *connector, bool force)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+	struct gud_drm_device *gdrm = to_gud_drm_device(connector->dev);
+	struct gud_drm_req_get_connector_status req;
+	u16 num_modes, edid_len;
+	int status, ret;
+	bool changed;
+
+	if (force) {
+		ret = gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_CONNECTOR_FORCE_DETECT,
+				      connector->index, NULL, 0);
+		if (ret)
+			goto free;
+	}
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_STATUS,
+			      connector->index, &req, sizeof(req));
+	if (ret)
+		goto free;
+
+	changed = req.status & GUD_DRM_CONNECTOR_STATUS_CHANGED;
+	status = req.status & GUD_DRM_CONNECTOR_STATUS_MASK;
+	if (status > connector_status_unknown)
+		status = connector_status_unknown;
+	num_modes = le16_to_cpu(req.num_modes);
+	edid_len = le16_to_cpu(req.edid_len);
+
+	if (!num_modes && !edid_len) {
+		ret = connector_status_disconnected;
+		goto free;
+	}
+
+	if (!changed && connector->status == status &&
+	    gconn->num_modes == num_modes && gconn->edid_len == edid_len)
+		return status;
+
+	ret = gud_drm_connector_modes_get(gconn, num_modes);
+	if (ret)
+		goto free;
+
+	ret = gud_drm_connector_edid_get(gconn, edid_len);
+	if (ret)
+		goto free;
+
+	return status;
+free:
+	gud_drm_connector_modes_clear(gconn);
+	gud_drm_connector_edid_clear(gconn);
+
+	return ret < 0 ? connector_status_unknown : ret;
+}
+
+static int gud_drm_connector_detect(struct drm_connector *connector,
+				    struct drm_modeset_acquire_ctx *ctx, bool force)
+{
+	int idx, ret;
+
+	if (!drm_dev_enter(connector->dev, &idx))
+		return -ENODEV;
+
+	ret = gud_drm_connector_detect_safe(connector, force);
+
+	drm_dev_exit(idx);
+
+	return ret;
+}
+
+static int gud_drm_connector_get_modes(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+	unsigned int i, num_modes = 0;
+
+	if (!gconn->num_modes)
+		return drm_add_edid_modes(connector, gconn->edid);
+
+	for (i = 0; i < gconn->num_modes; i++) {
+		struct drm_display_mode *mode;
+
+		mode = drm_mode_create(connector->dev);
+		if (!mode)
+			goto out;
+
+		gud_drm_to_display_mode(mode, &gconn->modes[i]);
+
+		drm_mode_probed_add(connector, mode);
+		num_modes++;
+	}
+out:
+	if (gconn->edid_len)
+		drm_connector_update_edid_property(connector, gconn->edid);
+
+	return num_modes;
+}
+
+static int gud_drm_connector_atomic_check(struct drm_connector *connector,
+					  struct drm_atomic_state *state)
+{
+	struct drm_connector_state *new_state;
+	struct drm_crtc_state *new_crtc_state;
+	struct drm_connector_state *old_state;
+
+	new_state = drm_atomic_get_new_connector_state(state, connector);
+	if (!new_state->crtc)
+		return 0;
+
+	old_state = drm_atomic_get_old_connector_state(state, connector);
+	new_crtc_state = drm_atomic_get_new_crtc_state(state, new_state->crtc);
+
+	if (old_state->tv.subconnector != new_state->tv.subconnector ||
+	    old_state->tv.margins.left != new_state->tv.margins.left ||
+	    old_state->tv.margins.right != new_state->tv.margins.right ||
+	    old_state->tv.margins.top != new_state->tv.margins.top ||
+	    old_state->tv.margins.bottom != new_state->tv.margins.bottom ||
+	    old_state->tv.mode != new_state->tv.mode ||
+	    old_state->tv.brightness != new_state->tv.brightness ||
+	    old_state->tv.contrast != new_state->tv.contrast ||
+	    old_state->tv.flicker_reduction != new_state->tv.flicker_reduction ||
+	    old_state->tv.overscan != new_state->tv.overscan ||
+	    old_state->tv.saturation != new_state->tv.saturation ||
+	    old_state->tv.hue != new_state->tv.hue)
+		new_crtc_state->connectors_changed = true;
+
+	return 0;
+}
+
+static const struct drm_connector_helper_funcs gud_drm_connector_helper_funcs = {
+	.detect_ctx = gud_drm_connector_detect,
+	.get_modes = gud_drm_connector_get_modes,
+	.atomic_check = gud_drm_connector_atomic_check,
+};
+
+static int gud_drm_connector_late_register(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	if (gconn->initial_brightness < 0)
+		return 0;
+
+	return gud_drm_connector_backlight_register(gconn);
+}
+
+static void gud_drm_connector_early_unregister(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	backlight_device_unregister(gconn->backlight);
+}
+
+static void gud_drm_connector_destroy(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	drm_connector_cleanup(connector);
+	gud_drm_connector_modes_clear(gconn);
+	gud_drm_connector_edid_clear(gconn);
+	kfree(gconn->properties);
+	kfree(gconn);
+}
+
+static void gud_drm_connector_reset(struct drm_connector *connector)
+{
+	struct gud_drm_connector *gconn = to_gud_drm_connector(connector);
+
+	drm_atomic_helper_connector_reset(connector);
+	connector->state->tv = gconn->initial_tv_state;
+	/* Set margins from command line */
+	drm_atomic_helper_connector_tv_reset(connector);
+	if (gconn->initial_brightness >= 0)
+		connector->state->tv.brightness = gconn->initial_brightness;
+}
+
+static const struct drm_connector_funcs gud_drm_connector_funcs = {
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.late_register = gud_drm_connector_late_register,
+	.early_unregister = gud_drm_connector_early_unregister,
+	.destroy = gud_drm_connector_destroy,
+	.reset = gud_drm_connector_reset,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+/*
+ * The tv.mode property is shared among the connectors and its enum names are
+ * driver specific. This means that if more than one connector uses tv.mode,
+ * the enum names has to be the same.
+ */
+static int gud_drm_connector_add_tv_mode(struct gud_drm_device *gdrm,
+					 struct drm_connector *connector, u64 val)
+{
+	unsigned int i, num_modes;
+	const char **modes;
+	size_t buf_len;
+	char *buf;
+	int ret;
+
+	num_modes = val >> GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT;
+
+	if (!num_modes)
+		return -EINVAL;
+
+	buf_len = num_modes * DRM_PROP_NAME_LEN;
+	modes = kmalloc_array(num_modes, sizeof(*modes), GFP_KERNEL);
+	buf = kmalloc(buf_len, GFP_KERNEL);
+	if (!modes || !buf) {
+		ret = -ENOMEM;
+		goto free;
+	}
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_TV_MODE_VALUES,
+			      connector->index, buf, buf_len);
+	if (ret)
+		goto free;
+
+	for (i = 0; i < num_modes; i++)
+		modes[i] = &buf[i * DRM_PROP_NAME_LEN];
+
+	ret = drm_mode_create_tv_properties(connector->dev, num_modes, modes);
+free:
+	kfree(modes);
+	kfree(buf);
+
+	return ret;
+}
+
+static struct drm_property *
+gud_drm_connector_property_lookup(struct drm_connector *connector, u16 prop)
+{
+	struct drm_mode_config *config = &connector->dev->mode_config;
+
+	switch (prop) {
+	case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+		return config->tv_select_subconnector_property;
+	case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+		return config->tv_left_margin_property;
+	case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+		return config->tv_right_margin_property;
+	case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+		return config->tv_top_margin_property;
+	case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+		return config->tv_bottom_margin_property;
+	case GUD_DRM_PROPERTY_TV_MODE:
+		return config->tv_mode_property;
+	case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+		return config->tv_brightness_property;
+	case GUD_DRM_PROPERTY_TV_CONTRAST:
+		return config->tv_contrast_property;
+	case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+		return config->tv_flicker_reduction_property;
+	case GUD_DRM_PROPERTY_TV_OVERSCAN:
+		return config->tv_overscan_property;
+	case GUD_DRM_PROPERTY_TV_SATURATION:
+		return config->tv_saturation_property;
+	case GUD_DRM_PROPERTY_TV_HUE:
+		return config->tv_hue_property;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+}
+
+static unsigned int *gud_drm_connector_tv_state_val(u16 prop, struct drm_tv_connector_state *state)
+{
+	switch (prop) {
+	case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+		return &state->subconnector;
+	case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+		return &state->margins.left;
+	case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+		return &state->margins.right;
+	case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+		return &state->margins.top;
+	case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+		return &state->margins.bottom;
+	case GUD_DRM_PROPERTY_TV_MODE:
+		return &state->mode;
+	case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+		return &state->brightness;
+	case GUD_DRM_PROPERTY_TV_CONTRAST:
+		return &state->contrast;
+	case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+		return &state->flicker_reduction;
+	case GUD_DRM_PROPERTY_TV_OVERSCAN:
+		return &state->overscan;
+	case GUD_DRM_PROPERTY_TV_SATURATION:
+		return &state->saturation;
+	case GUD_DRM_PROPERTY_TV_HUE:
+		return &state->hue;
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+}
+
+static int gud_drm_connector_add_properties(struct gud_drm_device *gdrm,
+					    struct gud_drm_connector *gconn,
+					    unsigned int num_properties)
+{
+	struct drm_device *drm = &gdrm->drm;
+	struct drm_connector *connector = &gconn->connector;
+	struct gud_drm_property *properties;
+	bool need_tv_props = false;
+	unsigned int i;
+	int ret;
+
+	gconn->properties = kcalloc(num_properties, sizeof(*gconn->properties), GFP_KERNEL);
+	if (!gconn->properties)
+		return -ENOMEM;
+
+	properties = kcalloc(num_properties, sizeof(*properties), GFP_KERNEL);
+	if (!properties)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR_PROPERTIES, connector->index,
+			      properties, num_properties * sizeof(*properties));
+	if (ret)
+		goto out;
+
+	for (i = 0; i < num_properties; i++) {
+		u16 prop = le16_to_cpu(properties[i].prop);
+		u64 val = le64_to_cpu(properties[i].val);
+
+		drm_dbg(drm, "property: %u = %llu(0x%llx)\n", prop, val, val);
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+			ret = drm_mode_create_tv_margin_properties(drm);
+			if (ret)
+				goto out;
+			break;
+		case GUD_DRM_PROPERTY_TV_MODE:
+			ret = gud_drm_connector_add_tv_mode(gdrm, connector, val);
+			if (ret)
+				goto out;
+			break;
+		case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_CONTRAST:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_OVERSCAN:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_SATURATION:
+			fallthrough;
+		case GUD_DRM_PROPERTY_TV_HUE:
+			need_tv_props = true;
+			break;
+		case GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS:
+			if (val > 100) {
+				ret = -EINVAL;
+				goto out;
+			}
+			gconn->initial_brightness = val;
+			break;
+		default:
+			/* New ones might show up in future devices, skip those we don't know. */
+			drm_dbg(drm, "Unknown property: %u\n", prop);
+			continue;
+		}
+
+		gconn->properties[gconn->num_properties++] = prop;
+	}
+
+	if (!gconn->num_properties)
+		goto out;
+
+	if (need_tv_props) {
+		/* This is a no-op if already added. */
+		ret = drm_mode_create_tv_properties(drm, 0, NULL);
+		if (ret)
+			goto out;
+	}
+
+	for (i = 0; i < num_properties; i++) {
+		u16 prop = le16_to_cpu(properties[i].prop);
+		u64 val = le64_to_cpu(properties[i].val);
+		struct drm_property *property;
+		unsigned int *state_val;
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS:
+			/* not a DRM property */
+			continue;
+		case GUD_DRM_PROPERTY_TV_MODE:
+			val = val & (BIT(GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT) - 1);
+			break;
+		}
+
+		property = gud_drm_connector_property_lookup(connector, prop);
+		if (IS_ERR(property))
+			continue;
+
+		state_val = gud_drm_connector_tv_state_val(prop, &gconn->initial_tv_state);
+		if (IS_ERR(state_val))
+			continue;
+
+		*state_val = val;
+		drm_object_attach_property(&connector->base, property, 0);
+	}
+out:
+	kfree(properties);
+
+	return ret;
+}
+
+int gud_drm_connector_fill_properties(struct drm_connector *connector,
+				      struct drm_connector_state *connector_state,
+				      struct gud_drm_property *properties)
+{
+	struct gud_drm_connector *gconn;
+	unsigned int i;
+
+	gconn = to_gud_drm_connector(connector);
+
+	/* Only interested in the count? */
+	if (!connector_state)
+		return gconn->num_properties;
+
+	for (i = 0; i < gconn->num_properties; i++) {
+		u16 prop = gconn->properties[i];
+		u64 val;
+
+		if (prop == GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS) {
+			val = connector_state->tv.brightness;
+		} else {
+			unsigned int *state_val;
+
+			state_val = gud_drm_connector_tv_state_val(prop, &connector_state->tv);
+			if (WARN_ON_ONCE(IS_ERR(state_val)))
+				return PTR_ERR(state_val);
+
+			val = *state_val;
+		}
+
+		properties[i].prop = cpu_to_le16(prop);
+		properties[i].val = cpu_to_le64(val);
+	}
+
+	return gconn->num_properties;
+}
+
+int gud_drm_connector_create(struct gud_drm_device *gdrm, unsigned int index)
+{
+	struct gud_drm_req_get_connector desc;
+	struct drm_device *drm = &gdrm->drm;
+	struct gud_drm_connector *gconn;
+	struct drm_connector *connector;
+	struct drm_encoder *encoder;
+	int ret;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_CONNECTOR, index, &desc, sizeof(desc));
+	if (ret)
+		return ret;
+
+	drm_dbg(drm, "index=%u type=%u flags=0x%x num_properties=%u\n", index,
+		desc.connector_type, le32_to_cpu(desc.flags), desc.num_properties);
+
+	/* REVISIT: This needs to be updated as new types are added */
+	if (desc.connector_type > DRM_MODE_CONNECTOR_SPI)
+		return -EINVAL;
+
+	gconn = kzalloc(sizeof(*gconn), GFP_KERNEL);
+	if (!gconn)
+		return -ENOMEM;
+
+	gconn->initial_brightness = -ENODEV;
+	gconn->flags = le32_to_cpu(desc.flags);
+	connector = &gconn->connector;
+
+	drm_connector_helper_add(connector, &gud_drm_connector_helper_funcs);
+	ret = drm_connector_init(drm, connector, &gud_drm_connector_funcs, desc.connector_type);
+	if (ret) {
+		kfree(connector);
+		return ret;
+	}
+
+	if (WARN_ON(connector->index != index))
+		return -EINVAL;
+
+	if (gconn->flags & GUD_DRM_CONNECTOR_FLAGS_POLL)
+		connector->polled = (DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT);
+
+	if (desc.num_properties) {
+		ret = gud_drm_connector_add_properties(gdrm, gconn, desc.num_properties);
+		if (ret) {
+			dev_err(drm->dev, "Failed to add connector/%u properties\n", index);
+			return ret;
+		}
+	}
+
+	/* The first connector is attached to the existing simple pipe encoder */
+	if (!connector->index) {
+		encoder = &gdrm->pipe.encoder;
+	} else {
+		encoder = &gconn->encoder;
+
+		ret = drm_simple_encoder_init(drm, encoder, DRM_MODE_ENCODER_NONE);
+		if (ret)
+			return ret;
+
+		encoder->possible_crtcs = 1;
+	}
+
+	return drm_connector_attach_encoder(connector, encoder);
+}
diff --git a/drivers/gpu/drm/gud/gud_drm_drv.c b/drivers/gpu/drm/gud/gud_drm_drv.c
new file mode 100644
index 000000000000..3f2e8c1d9a38
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_drv.c
@@ -0,0 +1,641 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/lz4.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/string_helpers.h>
+#include <linux/usb.h>
+#include <linux/workqueue.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_debugfs.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+/* Only used internally */
+static const struct drm_format_info gud_drm_format_r1 = {
+	.format = GUD_DRM_FORMAT_R1,
+	.num_planes = 1,
+	.char_per_block = { 1, 0, 0 },
+	.block_w = { 8, 0, 0 },
+	.block_h = { 1, 0, 0 },
+	.hsub = 1,
+	.vsub = 1,
+};
+
+static int gud_drm_usb_control_msg(struct usb_device *usb, u8 ifnum, bool in,
+				   u8 request, u16 value, void *buf, size_t len,
+				   bool check_len)
+{
+	u8 requesttype = USB_TYPE_VENDOR | USB_RECIP_INTERFACE;
+	unsigned int pipe;
+	int ret;
+
+	if (in) {
+		pipe = usb_rcvctrlpipe(usb, 0);
+		requesttype |= USB_DIR_IN;
+	} else {
+		pipe = usb_sndctrlpipe(usb, 0);
+		requesttype |= USB_DIR_OUT;
+	}
+
+	ret = usb_control_msg(usb, pipe, request, requesttype, value,
+			      ifnum, buf, len, USB_CTRL_GET_TIMEOUT);
+
+	if (check_len && ret >= 0) {
+		if (ret != len)
+			ret = -EIO;
+		else
+			ret = 0;
+	}
+
+	return ret;
+}
+
+static int gud_get_vendor_descriptor(struct usb_interface *interface,
+				     struct gud_drm_display_descriptor *desc)
+{
+	u8 ifnum = interface->cur_altsetting->desc.bInterfaceNumber;
+	struct usb_device *usb = interface_to_usbdev(interface);
+	void *buf;
+	int ret;
+
+	buf = kmalloc(sizeof(*desc), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_control_msg(usb, ifnum, true, USB_REQ_GET_DESCRIPTOR,
+				      GUD_DRM_USB_DT_DISPLAY << 8, buf, sizeof(*desc), false);
+
+	memcpy(desc, buf, sizeof(*desc));
+	kfree(buf);
+
+	if (ret < 0)
+		return ret;
+
+	if (ret != sizeof(*desc) || desc->bLength != sizeof(*desc) ||
+	    desc->bDescriptorType != GUD_DRM_USB_DT_DISPLAY)
+		return -ENODATA;
+
+	DRM_DEV_DEBUG_DRIVER(&interface->dev,
+			     "Version=%u Compression=0x%x NumFormats=%u NumConnectors=%u MaxBufferSizeOrder=%u\n",
+			     desc->bVersion, desc->bCompression, desc->bNumFormats,
+			     desc->bNumConnectors, desc->bMaxBufferSizeOrder);
+
+	if (!desc->bVersion || !desc->bNumFormats || !desc->bNumConnectors ||
+	    !desc->bMaxBufferSizeOrder || !desc->dwMaxWidth || !desc->dwMaxHeight ||
+	    le32_to_cpu(desc->dwMinWidth) > le32_to_cpu(desc->dwMaxWidth) ||
+	    le32_to_cpu(desc->dwMinHeight) > le32_to_cpu(desc->dwMaxHeight))
+		return -EINVAL;
+
+	return 0;
+}
+
+static int gud_usb_get_status(struct gud_drm_device *gdrm)
+{
+	struct gud_drm_req_get_status *status = gdrm->status_buf;
+	int ret, status_retries = 2000 / 5; /* maximum wait ~2 seconds */
+	unsigned long delay = 500;
+
+	/*
+	 * Poll due to lack of data/status stage control on the gadget side.
+	 *
+	 * If we did not use polling and gave up here after waiting 2 seconds,
+	 * the worker in the gadget would finally get to queuing up the status
+	 * respons, but by that time the host has moved on. The gadget side
+	 * (at least dwc2) would now be left in a non-recoverable state.
+	 *
+	 * Worst case commit timeout in DRM can be tens of seconds (wait for
+	 * various _done completions).
+	 */
+	while (status_retries--) {
+		ret = gud_drm_usb_control_msg(gdrm->usb, gdrm->ifnum, true, USB_REQ_GET_STATUS,
+					      0, status, sizeof(*status), true);
+		if (ret)
+			return ret;
+
+		if (!(status->flags & GUD_DRM_STATUS_PENDING))
+			return -status->errno;
+
+		usleep_range(delay, delay + 1000);
+
+		if (delay < 4500)
+			delay += 1000;
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int gud_usb_transfer(struct gud_drm_device *gdrm, bool in, u8 request,
+			    u16 index, void *buf, size_t len)
+{
+	int idx, ret;
+
+	drm_dbg(&gdrm->drm, "%s: request=0x%x index=%u len=%zu\n",
+		in ? "get" : "set", request, index, len);
+
+	if (len > GUD_DRM_MAX_TRANSFER_SIZE)
+		return -ENOMEM;
+
+	if (!drm_dev_enter(&gdrm->drm, &idx))
+		return -ENODEV;
+
+	mutex_lock(&gdrm->ctrl_lock);
+
+	if (!in && buf)
+		memcpy(gdrm->ctrl_msg_buf, buf, len);
+
+	ret = gud_drm_usb_control_msg(gdrm->usb, gdrm->ifnum, in, request, index,
+				      gdrm->ctrl_msg_buf, len, true);
+
+	/*
+	 * OUT transfers are processed in a worker on the gadget side after
+	 * reception so we always need to check status. IN transfers are
+	 * processed in the interrupt handler and will halt on error letting us
+	 * know something went wrong.
+	 */
+	if (ret || !in) {
+		ret = gud_usb_get_status(gdrm);
+		if (ret)
+			goto error;
+	}
+
+	if (in && buf)
+		memcpy(buf, gdrm->ctrl_msg_buf, len);
+error:
+	if (ret) {
+		drm_dbg(&gdrm->drm, "ret=%d\n", ret);
+		gdrm->stats_num_errors++;
+	}
+
+	mutex_unlock(&gdrm->ctrl_lock);
+	drm_dev_exit(idx);
+
+	return ret;
+}
+
+int gud_drm_usb_get(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len)
+{
+	return gud_usb_transfer(gdrm, true, request, index, buf, len);
+}
+
+int gud_drm_usb_set(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len)
+{
+	return gud_usb_transfer(gdrm, false, request, index, buf, len);
+}
+
+int gud_drm_usb_write8(struct gud_drm_device *gdrm, u8 request, u8 val)
+{
+	return gud_drm_usb_set(gdrm, request, 0, &val, sizeof(val));
+}
+
+static int gud_drm_usb_read32(struct gud_drm_device *gdrm, u8 request,
+			      u32 *vals, unsigned int num_vals)
+{
+	unsigned int i;
+	int ret;
+
+	ret = gud_drm_usb_get(gdrm, request, 0, vals, num_vals * sizeof(*vals));
+	if (ret)
+		return ret;
+
+	for (i = 0; i < num_vals; i++)
+		vals[i] = le32_to_cpu((__le32)vals[i]);
+
+	return 0;
+}
+
+static int gud_drm_get_properties(struct gud_drm_device *gdrm, unsigned int num_properties)
+{
+	struct gud_drm_property *properties;
+	unsigned int i;
+	int ret;
+
+	if (!num_properties)
+		return 0;
+
+	gdrm->properties = kcalloc(num_properties, sizeof(*gdrm->properties), GFP_KERNEL);
+	if (!gdrm->properties)
+		return -ENOMEM;
+
+	properties = kcalloc(num_properties, sizeof(*properties), GFP_KERNEL);
+	if (!properties)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_get(gdrm, GUD_DRM_USB_REQ_GET_PROPERTIES, 0,
+			      properties, num_properties * sizeof(*properties));
+	if (ret)
+		goto out;
+
+	for (i = 0; i < num_properties; i++) {
+		u16 prop = le16_to_cpu(properties[i].prop);
+		u64 val = le64_to_cpu(properties[i].val);
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_ROTATION:
+			ret = drm_plane_create_rotation_property(&gdrm->pipe.plane,
+								 DRM_MODE_ROTATE_0, val);
+			break;
+		default:
+			/* New ones might show up in future devices, skip those we don't know. */
+			drm_dbg(&gdrm->drm, "Unknown property: %u\n", prop);
+			continue;
+		}
+
+		if (ret)
+			goto out;
+
+		gdrm->properties[gdrm->num_properties++] = prop;
+	}
+out:
+	kfree(properties);
+
+	return ret;
+}
+
+static struct drm_gem_object *
+gud_drm_driver_gem_create_object(struct drm_device *dev, size_t size)
+{
+	struct drm_gem_shmem_object *shmem;
+
+	shmem = kzalloc(sizeof(*shmem), GFP_KERNEL);
+	if (!shmem)
+		return NULL;
+
+	/*
+	 * This doesn't make a difference on x86, but on ARM (pi4) it was
+	 * necessary to avoid black lines all over and it made it possible to
+	 * compress directly from the framebuffer without performance drop.
+	 */
+	shmem->map_cached = true;
+
+	return &shmem->base;
+}
+
+static int gud_drm_stats_debugfs(struct seq_file *m, void *data)
+{
+	struct drm_info_node *node = m->private;
+	struct gud_drm_device *gdrm = to_gud_drm_device(node->minor->dev);
+	char buf[10];
+
+	string_get_size(gdrm->bulk_len, 1, STRING_UNITS_2, buf, sizeof(buf));
+	seq_printf(m, "Max buffer size: %s\n", buf);
+	seq_printf(m, "Number of errors:  %u\n", gdrm->stats_num_errors);
+
+	seq_puts(m, "Compression:      ");
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4)
+		seq_puts(m, " lz4");
+	seq_puts(m, "\n");
+
+	if (gdrm->compression) {
+		u64 remainder;
+		u64 ratio = div64_u64_rem(gdrm->stats_length, gdrm->stats_actual_length,
+					  &remainder);
+		u64 ratio_frac = div64_u64(remainder * 10, gdrm->stats_actual_length);
+
+		seq_printf(m, "Compression ratio: %llu.%llu\n", ratio, ratio_frac);
+	}
+
+	return 0;
+}
+
+static const struct drm_info_list gud_drm_debugfs_list[] = {
+	{ "stats", gud_drm_stats_debugfs, 0, NULL },
+};
+
+static void gud_drm_driver_debugfs_init(struct drm_minor *minor)
+{
+	drm_debugfs_create_files(gud_drm_debugfs_list, ARRAY_SIZE(gud_drm_debugfs_list),
+				 minor->debugfs_root, minor);
+}
+
+static const struct drm_simple_display_pipe_funcs gud_drm_pipe_funcs = {
+	.check      = gud_drm_pipe_check,
+	.update	    = gud_drm_pipe_update,
+	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+static const struct drm_mode_config_funcs gud_drm_mode_config_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+static const uint64_t gud_drm_pipe_modifiers[] = {
+	DRM_FORMAT_MOD_LINEAR,
+	DRM_FORMAT_MOD_INVALID
+};
+
+DEFINE_DRM_GEM_FOPS(gud_drm_fops);
+
+static struct drm_driver gud_drm_driver = {
+	.driver_features	= DRIVER_MODESET | DRIVER_GEM | DRIVER_ATOMIC,
+	.fops			= &gud_drm_fops,
+	.gem_create_object	= gud_drm_driver_gem_create_object,
+	DRM_GEM_SHMEM_DRIVER_OPS,
+	.debugfs_init		= gud_drm_driver_debugfs_init,
+
+	.name			= "gud_drm",
+	.desc			= "Generic USB Display",
+	.date			= "20200422",
+	.major			= 1,
+	.minor			= 0,
+};
+
+static void gud_drm_free_buffers_and_mutex(void *data)
+{
+	struct gud_drm_device *gdrm = data;
+
+	/* Access to these are protected by drm_dev_enter/exit */
+
+	kfree(gdrm->properties);
+	vfree(gdrm->compress_buf);
+	kfree(gdrm->bulk_buf);
+	kfree(gdrm->ctrl_msg_buf);
+	gdrm->properties = NULL;
+	gdrm->compress_buf = NULL;
+	gdrm->bulk_buf = NULL;
+	gdrm->ctrl_msg_buf = NULL;
+
+	mutex_destroy(&gdrm->ctrl_lock);
+	mutex_destroy(&gdrm->damage_lock);
+}
+
+static int gud_drm_probe(struct usb_interface *interface,
+			 const struct usb_device_id *id)
+{
+	u8 ifnum = interface->cur_altsetting->desc.bInterfaceNumber;
+	struct usb_device *usb = interface_to_usbdev(interface);
+	const struct drm_format_info *xrgb8888_emulation_format = NULL;
+	u32 *formats, *formats_dev, num_connectors, num_formats = 0;
+	bool rgb565_supported = false, rgb8888_supported = false;
+	struct usb_endpoint_descriptor *bulk_out;
+	struct gud_drm_display_descriptor desc;
+	struct device *dev = &interface->dev;
+	struct gud_drm_device *gdrm;
+	struct drm_device *drm;
+	size_t max_buffer_size;
+	int ret, i;
+
+	ret = usb_find_bulk_out_endpoint(interface->cur_altsetting, &bulk_out);
+	if (ret)
+		return ret;
+
+	ret = gud_get_vendor_descriptor(interface, &desc);
+	if (ret) {
+		DRM_DEV_DEBUG_DRIVER(dev, "Not a display interface: ret=%d\n", ret);
+		return -ENODEV;
+	}
+
+	if (desc.bVersion > 1) {
+		u8 *version = kmalloc(sizeof(*version), GFP_KERNEL);
+
+		if (!version)
+			return -ENOMEM;
+
+		/* Check if the device can support us */
+		*version = 1;
+		ret = gud_drm_usb_control_msg(usb, ifnum, false, GUD_DRM_USB_REQ_SET_VERSION,
+					      0, version, sizeof(*version), true);
+		kfree(version);
+		if (ret) {
+			dev_err(dev, "Protocol version %u is not supported\n", desc.bVersion);
+			return -EPROTONOSUPPORT;
+		}
+
+		desc.bVersion = 1;
+	}
+
+	num_connectors = desc.bNumConnectors;
+	max_buffer_size = 1 << desc.bMaxBufferSizeOrder;
+
+	gdrm = devm_drm_dev_alloc(dev, &gud_drm_driver, struct gud_drm_device, drm);
+	if (IS_ERR(gdrm))
+		return PTR_ERR(gdrm);
+
+	drm = &gdrm->drm;
+	drm->mode_config.funcs = &gud_drm_mode_config_funcs;
+	ret = drmm_mode_config_init(drm);
+	if (ret)
+		return ret;
+
+	gdrm->usb = usb;
+	gdrm->ifnum = ifnum;
+	gdrm->compression = desc.bCompression & GUD_DRM_COMPRESSION_LZ4;
+
+	mutex_init(&gdrm->ctrl_lock);
+	mutex_init(&gdrm->damage_lock);
+	INIT_WORK(&gdrm->work, gud_drm_work);
+	gud_drm_clear_damage(gdrm);
+
+	/*
+	 * devm_kmalloc() places struct devres at the beginning of the buffer it
+	 * allocates. This can waste a lot of memory when allocating
+	 * power-of-two sized buffers. Asking for 4k would actually allocate 8k.
+	 */
+
+	ret = devm_add_action_or_reset(dev, gud_drm_free_buffers_and_mutex, gdrm);
+	if (ret)
+		return ret;
+
+	gdrm->ctrl_msg_buf = kmalloc(GUD_DRM_MAX_TRANSFER_SIZE, GFP_KERNEL);
+	gdrm->status_buf = devm_kzalloc(dev, sizeof(struct gud_drm_req_get_status), GFP_KERNEL);
+	if (!gdrm->ctrl_msg_buf || !gdrm->status_buf)
+		return -ENOMEM;
+retry:
+	gdrm->bulk_buf = kmalloc(max_buffer_size, GFP_KERNEL);
+	if (!gdrm->bulk_buf) {
+		max_buffer_size /= 2;
+		if (max_buffer_size < SZ_2M) { /* Give up if we can't do 1024x768 RGB565 */
+			return -ENOMEM;
+		}
+		goto retry;
+	}
+
+	gdrm->bulk_pipe = usb_sndbulkpipe(gdrm->usb, usb_endpoint_num(bulk_out));
+	gdrm->bulk_len = max_buffer_size;
+
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4) {
+		gdrm->lz4_comp_mem = devm_kmalloc(dev, LZ4_MEM_COMPRESS, GFP_KERNEL);
+		if (!gdrm->lz4_comp_mem)
+			return -ENOMEM;
+
+		gdrm->compress_buf = vmalloc(gdrm->bulk_len);
+		if (!gdrm->compress_buf)
+			return -ENOMEM;
+	}
+
+	drm->mode_config.min_width = le32_to_cpu(desc.dwMinWidth);
+	drm->mode_config.max_width = le32_to_cpu(desc.dwMaxWidth);
+	drm->mode_config.min_height = le32_to_cpu(desc.dwMinHeight);
+	drm->mode_config.max_height = le32_to_cpu(desc.dwMaxHeight);
+
+	formats_dev = devm_kmalloc_array(dev, desc.bNumFormats, sizeof(u32), GFP_KERNEL);
+	/* Add room for emulated XRGB8888 */
+	formats = devm_kmalloc_array(dev, desc.bNumFormats + 1, sizeof(u32), GFP_KERNEL);
+	if (!formats_dev || !formats)
+		return -ENOMEM;
+
+	ret = gud_drm_usb_read32(gdrm, GUD_DRM_USB_REQ_GET_FORMATS, formats_dev, desc.bNumFormats);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < desc.bNumFormats; i++) {
+		const struct drm_format_info *fmt_info;
+		u32 format = formats_dev[i];
+
+		if (format == GUD_DRM_FORMAT_R1) {
+			fmt_info = &gud_drm_format_r1;
+		} else {
+			/* This will trigger a WARN for unknown formats... */
+			fmt_info = drm_format_info(format);
+			if (!fmt_info) {
+				drm_dbg(drm, "Unknown format: 0x%x\n", format);
+				continue;
+			}
+		}
+
+		switch (format) {
+		case DRM_FORMAT_XRGB8888:
+			fallthrough;
+		case DRM_FORMAT_ARGB8888:
+			rgb8888_supported = true;
+			break;
+		case DRM_FORMAT_RGB888:
+			fallthrough;
+		case DRM_FORMAT_BGR888:
+			drm_dbg(drm, "24-bit formats are not supported.\n");
+			continue;
+		case DRM_FORMAT_RGB565:
+			rgb565_supported = true;
+			if (!xrgb8888_emulation_format)
+				xrgb8888_emulation_format = fmt_info;
+			break;
+		case GUD_DRM_FORMAT_R1:
+			if (!xrgb8888_emulation_format)
+				xrgb8888_emulation_format = fmt_info;
+			/* Internal, not for userspace */
+			continue;
+		}
+
+		formats[num_formats++] = format;
+	}
+
+	if (!num_formats && !xrgb8888_emulation_format) {
+		dev_err(dev, "No supported formats found\n");
+		return -ENOENT;
+	}
+
+	/* Prefer speed over color depth */
+	if (rgb565_supported)
+		drm->mode_config.preferred_depth = 16;
+
+	if (!rgb8888_supported && xrgb8888_emulation_format) {
+		gdrm->xrgb8888_emulation_format = xrgb8888_emulation_format;
+		formats[num_formats++] = DRM_FORMAT_XRGB8888;
+	}
+
+	ret = drm_simple_display_pipe_init(drm, &gdrm->pipe, &gud_drm_pipe_funcs,
+					   formats, num_formats,
+					   gud_drm_pipe_modifiers, NULL);
+	if (ret)
+		return ret;
+
+	devm_kfree(dev, formats);
+	devm_kfree(dev, formats_dev);
+
+	ret = gud_drm_get_properties(gdrm, desc.bNumProperties);
+	if (ret)
+		return ret;
+
+	drm_plane_enable_fb_damage_clips(&gdrm->pipe.plane);
+
+	for (i = 0; i < num_connectors; i++) {
+		ret = gud_drm_connector_create(gdrm, i);
+		if (ret)
+			return ret;
+	}
+
+	drm_mode_config_reset(drm);
+
+	usb_set_intfdata(interface, gdrm);
+
+	ret = drm_dev_register(drm, 0);
+	if (ret)
+		return ret;
+
+	drm_kms_helper_poll_init(drm);
+
+	drm_fbdev_generic_setup(drm, 0);
+
+	return 0;
+}
+
+static void gud_drm_disconnect(struct usb_interface *interface)
+{
+	struct gud_drm_device *gdrm = usb_get_intfdata(interface);
+	struct drm_device *drm = &gdrm->drm;
+
+	drm_dbg(drm, "%s:\n", __func__);
+
+	drm_kms_helper_poll_fini(drm);
+	drm_dev_unplug(drm);
+	drm_atomic_helper_shutdown(drm);
+}
+
+static int gud_drm_suspend(struct usb_interface *interface, pm_message_t message)
+{
+	struct gud_drm_device *gdrm = usb_get_intfdata(interface);
+
+	return drm_mode_config_helper_suspend(&gdrm->drm);
+}
+
+static int gud_drm_resume(struct usb_interface *interface)
+{
+	struct gud_drm_device *gdrm = usb_get_intfdata(interface);
+
+	drm_mode_config_helper_resume(&gdrm->drm);
+
+	return 0;
+}
+
+static const struct usb_device_id gud_drm_table[] = {
+	/*
+	 * FIXME:
+	 * Apply for a proper pid: https://github.com/openmoko/openmoko-usb-oui
+	 */
+	{ USB_DEVICE_INTERFACE_CLASS(0x1d50, 0x6150, USB_CLASS_VENDOR_SPEC) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(usb, gud_drm_table);
+
+static struct usb_driver gud_drm_usb_driver = {
+	.name		= "gud_drm",
+	.probe		= gud_drm_probe,
+	.disconnect	= gud_drm_disconnect,
+	.id_table	= gud_drm_table,
+	.suspend	= gud_drm_suspend,
+	.resume		= gud_drm_resume,
+	.reset_resume	= gud_drm_resume,
+};
+
+module_usb_driver(gud_drm_usb_driver);
+
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("Dual MIT/GPL");
diff --git a/drivers/gpu/drm/gud/gud_drm_internal.h b/drivers/gpu/drm/gud/gud_drm_internal.h
new file mode 100644
index 000000000000..30d86bb0389d
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_internal.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef __LINUX_GUD_DRM_INTERNAL_H
+#define __LINUX_GUD_DRM_INTERNAL_H
+
+#include <linux/workqueue.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+
+#include <drm/drm_simple_kms_helper.h>
+
+struct gud_drm_device {
+	struct drm_device drm;
+	struct drm_simple_display_pipe pipe;
+	struct work_struct work;
+	struct usb_device *usb;
+	u8 ifnum;
+	const struct drm_format_info *xrgb8888_emulation_format;
+
+	u16 *properties;
+	unsigned int num_properties;
+
+	unsigned int bulk_pipe;
+	void *bulk_buf;
+	size_t bulk_len;
+
+	u8 compression;
+	void *lz4_comp_mem;
+	void *compress_buf;
+
+	u64 stats_length;
+	u64 stats_actual_length;
+	unsigned int stats_num_errors;
+
+	struct mutex ctrl_lock; /* Serialize req and status transfers */
+	void *ctrl_msg_buf;
+	void *status_buf;
+
+	struct mutex damage_lock; /* Protects the following members: */
+	struct drm_framebuffer *fb;
+	struct drm_rect damage;
+};
+
+static inline struct gud_drm_device *to_gud_drm_device(struct drm_device *drm)
+{
+	return container_of(drm, struct gud_drm_device, drm);
+}
+
+int gud_drm_usb_get(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len);
+int gud_drm_usb_set(struct gud_drm_device *gdrm, u8 request, u16 index, void *buf, size_t len);
+int gud_drm_usb_write8(struct gud_drm_device *gdrm, u8 request, u8 val);
+
+void gud_drm_clear_damage(struct gud_drm_device *gdrm);
+void gud_drm_work(struct work_struct *work);
+int gud_drm_pipe_check(struct drm_simple_display_pipe *pipe,
+		       struct drm_plane_state *new_plane_state,
+		       struct drm_crtc_state *new_crtc_state);
+void gud_drm_pipe_update(struct drm_simple_display_pipe *pipe,
+			 struct drm_plane_state *old_state);
+
+int gud_drm_connector_fill_properties(struct drm_connector *connector,
+				      struct drm_connector_state *connector_state,
+				      struct gud_drm_property *properties);
+int gud_drm_connector_create(struct gud_drm_device *gdrm, unsigned int index);
+
+#endif
diff --git a/drivers/gpu/drm/gud/gud_drm_pipe.c b/drivers/gpu/drm/gud/gud_drm_pipe.c
new file mode 100644
index 000000000000..95023f465dcb
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_pipe.c
@@ -0,0 +1,423 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/dma-buf.h>
+#include <linux/lz4.h>
+#include <linux/usb.h>
+#include <linux/workqueue.h>
+
+#include <drm/drm_atomic.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_print.h>
+#include <drm/drm_rect.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+static bool gud_drm_is_big_endian(void)
+{
+#if defined(__BIG_ENDIAN)
+	return true;
+#else
+	return false;
+#endif
+}
+
+static size_t gud_drm_xrgb8888_to_r124(u8 *dst, const struct drm_format_info *format,
+				       void *src, struct drm_framebuffer *fb,
+				       struct drm_rect *rect)
+{
+	unsigned int block_width = drm_format_info_block_width(format, 0);
+	unsigned int bits_per_pixel = 8 / block_width;
+	unsigned int x, y, width, height;
+	u8 *p, *block = dst; /* Assign to silence compiler warning */
+	size_t len;
+	void *buf;
+
+	WARN_ON_ONCE(format->char_per_block[0] != 1);
+
+	/* Start on a byte boundary */
+	rect->x1 = ALIGN_DOWN(rect->x1, block_width);
+	width = drm_rect_width(rect);
+	height = drm_rect_height(rect);
+	len = drm_format_info_min_pitch(format, 0, width) * height;
+
+	buf = kmalloc(width * height, GFP_KERNEL);
+	if (!buf)
+		return len; /* To keep logic simple, just transmit garbage */
+
+	drm_fb_xrgb8888_to_gray8(buf, src, fb, rect);
+
+	p = buf;
+	for (y = 0; y < drm_rect_height(rect); y++) {
+		for (x = 0; x < drm_rect_width(rect); x++) {
+			if (!(x % block_width)) {
+				block = dst++;
+				*block = 0;
+			}
+
+			*block <<= bits_per_pixel;
+			*block |= (*p++) >> (8 - bits_per_pixel);
+		}
+	}
+
+	kfree(buf);
+
+	return len;
+}
+
+static int gud_drm_fb_flush(struct gud_drm_device *gdrm, struct drm_framebuffer *fb,
+			    const struct drm_format_info *format, struct drm_rect *rect)
+{
+	struct dma_buf_attachment *import_attach = fb->obj[0]->import_attach;
+	struct gud_drm_req_set_buffer req;
+	size_t trlen, len;
+	int actual_length;
+	void *vaddr, *buf;
+	int ret = 0;
+
+	drm_dbg(&gdrm->drm, "Flushing [FB:%d] " DRM_RECT_FMT " imported=%s\n",
+		fb->base.id, DRM_RECT_ARG(rect), import_attach ? "yes" : "no");
+
+	len = drm_format_info_min_pitch(format, 0, drm_rect_width(rect)) * drm_rect_height(rect);
+	if (len > gdrm->bulk_len)
+		return -E2BIG;
+
+	vaddr = drm_gem_shmem_vmap(fb->obj[0]);
+	if (!vaddr)
+		return -ENOMEM;
+
+	if (import_attach) {
+		ret = dma_buf_begin_cpu_access(import_attach->dmabuf, DMA_FROM_DEVICE);
+		if (ret)
+			goto vunmap;
+	}
+
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4)
+		buf = gdrm->compress_buf;
+	else
+		buf = gdrm->bulk_buf;
+
+	/*
+	 * Imported buffers are assumed to be write-combined and thus uncached
+	 * with slow reads (at least on ARM).
+	 */
+	if (format != fb->format) {
+		if (format->format == GUD_DRM_FORMAT_R1)
+			len = gud_drm_xrgb8888_to_r124(buf, format, vaddr, fb, rect);
+		else if (format->format == DRM_FORMAT_RGB565)
+			drm_fb_xrgb8888_to_rgb565(buf, vaddr, fb, rect, gud_drm_is_big_endian());
+	} else if (gud_drm_is_big_endian() && format->cpp[0] > 1) {
+		drm_fb_swab(buf, vaddr, fb, rect, !import_attach);
+	} else if (!import_attach && gdrm->compression && len == fb->height * fb->pitches[0]) {
+		/* can compress directly from the framebuffer */
+		buf = vaddr;
+	} else {
+		drm_fb_memcpy(buf, vaddr, fb, rect);
+	}
+
+	req.x = cpu_to_le32(rect->x1);
+	req.y = cpu_to_le32(rect->y1);
+	req.width = cpu_to_le32(drm_rect_width(rect));
+	req.height = cpu_to_le32(drm_rect_height(rect));
+	req.length = cpu_to_le32(len);
+
+	if (gdrm->compression & GUD_DRM_COMPRESSION_LZ4) {
+		ret = LZ4_compress_default(buf, gdrm->bulk_buf, len, len, gdrm->lz4_comp_mem);
+		if (ret > 0)
+			req.compression = GUD_DRM_COMPRESSION_LZ4;
+	}
+
+	trlen = len;
+
+	if (ret > 0) {
+		req.compressed_length = cpu_to_le32(ret);
+		trlen = ret;
+	} else if (buf == gdrm->compress_buf) {
+		/*
+		 * Compression failed (buffer didn't compress well).
+		 * compress_buf is vmalloc'ed so we need to copy.
+		 */
+		memcpy(gdrm->bulk_buf, gdrm->compress_buf, len);
+	}
+
+	if (import_attach)
+		dma_buf_end_cpu_access(import_attach->dmabuf, DMA_FROM_DEVICE);
+
+	gdrm->stats_length += len;
+	/* Did it wrap around? */
+	if (gdrm->stats_length <= len && gdrm->stats_actual_length) {
+		gdrm->stats_length = len;
+		gdrm->stats_actual_length = 0;
+	}
+	gdrm->stats_actual_length += trlen;
+
+	/*
+	 * This will wait if decompress/copy from the previous flush is still in
+	 * process on the gadget side.
+	 */
+	ret = gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_BUFFER, 0, &req, sizeof(req));
+	if (ret)
+		goto vunmap;
+
+	ret = usb_bulk_msg(gdrm->usb, gdrm->bulk_pipe, gdrm->bulk_buf, trlen,
+			   &actual_length, msecs_to_jiffies(3000));
+	if (!ret && trlen != actual_length)
+		ret = -EIO;
+	if (ret)
+		gdrm->stats_num_errors++;
+vunmap:
+	drm_gem_shmem_vunmap(fb->obj[0], vaddr);
+
+	return ret;
+}
+
+void gud_drm_clear_damage(struct gud_drm_device *gdrm)
+{
+	gdrm->damage.x1 = INT_MAX;
+	gdrm->damage.y1 = INT_MAX;
+	gdrm->damage.x2 = 0;
+	gdrm->damage.y2 = 0;
+}
+
+void gud_drm_work(struct work_struct *work)
+{
+	struct gud_drm_device *gdrm = container_of(work, struct gud_drm_device, work);
+	const struct drm_format_info *format;
+	struct drm_framebuffer *fb;
+	struct drm_rect damage;
+	unsigned int i, lines;
+	int idx, ret = 0;
+	size_t pitch;
+
+	if (!drm_dev_enter(&gdrm->drm, &idx))
+		return;
+
+	mutex_lock(&gdrm->damage_lock);
+	fb = gdrm->fb;
+	gdrm->fb = NULL;
+	damage = gdrm->damage;
+	gud_drm_clear_damage(gdrm);
+	mutex_unlock(&gdrm->damage_lock);
+
+	if (!fb)
+		goto out;
+
+	format = fb->format;
+	if (format->format == DRM_FORMAT_XRGB8888 && gdrm->xrgb8888_emulation_format)
+		format = gdrm->xrgb8888_emulation_format;
+
+	/* Split update if it's too big */
+	pitch = drm_format_info_min_pitch(format, 0, drm_rect_width(&damage));
+	lines = drm_rect_height(&damage);
+
+	if (gdrm->bulk_len < lines * pitch)
+		lines = gdrm->bulk_len / pitch;
+
+	for (i = 0; i < DIV_ROUND_UP(drm_rect_height(&damage), lines); i++) {
+		struct drm_rect rect = damage;
+
+		rect.y1 += i * lines;
+		rect.y2 = min_t(u32, rect.y1 + lines, damage.y2);
+
+		ret = gud_drm_fb_flush(gdrm, fb, format, &rect);
+		if (ret &&
+		    (ret != -ENODEV && ret != -ECONNRESET && ret != -ESHUTDOWN && ret != -EPROTO))
+			dev_err_once(fb->dev->dev, "Failed to flush framebuffer: error=%d\n", ret);
+	}
+
+	drm_framebuffer_put(fb);
+out:
+	drm_dev_exit(idx);
+}
+
+static void gud_drm_fb_queue_damage(struct gud_drm_device *gdrm,
+				    struct drm_framebuffer *fb,
+				    struct drm_rect *damage)
+{
+	struct drm_framebuffer *old_fb = NULL;
+
+	mutex_lock(&gdrm->damage_lock);
+
+	if (fb != gdrm->fb) {
+		old_fb = gdrm->fb;
+		drm_framebuffer_get(fb);
+		gdrm->fb = fb;
+	}
+
+	gdrm->damage.x1 = min(gdrm->damage.x1, damage->x1);
+	gdrm->damage.y1 = min(gdrm->damage.y1, damage->y1);
+	gdrm->damage.x2 = max(gdrm->damage.x2, damage->x2);
+	gdrm->damage.y2 = max(gdrm->damage.y2, damage->y2);
+
+	mutex_unlock(&gdrm->damage_lock);
+
+	queue_work(system_long_wq, &gdrm->work);
+
+	if (old_fb)
+		drm_framebuffer_put(old_fb);
+}
+
+int gud_drm_pipe_check(struct drm_simple_display_pipe *pipe,
+		       struct drm_plane_state *new_plane_state,
+		       struct drm_crtc_state *new_crtc_state)
+{
+	struct gud_drm_device *gdrm = to_gud_drm_device(pipe->crtc.dev);
+	struct drm_plane_state *old_plane_state = pipe->plane.state;
+	const struct drm_display_mode *mode = &new_crtc_state->mode;
+	struct drm_atomic_state *state = new_plane_state->state;
+	struct drm_framebuffer *old_fb = old_plane_state->fb;
+	struct drm_connector_state *connector_state = NULL;
+	struct drm_framebuffer *fb = new_plane_state->fb;
+	const struct drm_format_info *format = fb->format;
+	struct gud_drm_req_set_state *req;
+	struct drm_connector *connector;
+	int idx, ret, num_properties;
+	unsigned int i;
+	size_t len;
+
+	if (WARN_ON_ONCE(!fb))
+		return -EINVAL;
+
+	if (old_plane_state->rotation != new_plane_state->rotation)
+		new_crtc_state->mode_changed = true;
+
+	if (old_fb && old_fb->format != format)
+		new_crtc_state->mode_changed = true;
+
+	if (!new_crtc_state->mode_changed && !new_crtc_state->connectors_changed)
+		return 0;
+
+	/* Only one connector is supported */
+	if (hweight32(new_crtc_state->connector_mask) != 1)
+		return -EINVAL;
+
+	if (format->format == DRM_FORMAT_XRGB8888 && gdrm->xrgb8888_emulation_format)
+		format = gdrm->xrgb8888_emulation_format;
+
+	for_each_new_connector_in_state(state, connector, connector_state, i)
+		break;
+
+	if (!connector_state) {
+		struct drm_connector_list_iter conn_iter;
+
+		/* We always send the full state to the device, so get the connector state */
+
+		drm_connector_list_iter_begin(pipe->crtc.dev, &conn_iter);
+		drm_for_each_connector_iter(connector, &conn_iter) {
+			if (new_crtc_state->connector_mask & drm_connector_mask(connector))
+				break;
+		}
+		drm_connector_list_iter_end(&conn_iter);
+
+		if (WARN_ON_ONCE(!connector))
+			return -ENOENT;
+
+		connector_state = drm_atomic_get_connector_state(state, connector);
+		if (IS_ERR(connector_state))
+			return PTR_ERR(connector_state);
+	}
+
+	num_properties = gud_drm_connector_fill_properties(connector, NULL, NULL);
+	if (num_properties < 0)
+		return num_properties;
+
+	num_properties += gdrm->num_properties;
+
+	len = struct_size(req, properties, num_properties);
+	req = kzalloc(len, GFP_KERNEL);
+	if (!req)
+		return -ENOMEM;
+
+	gud_drm_from_display_mode(&req->mode, mode);
+
+	req->format = cpu_to_le32(format->format);
+	req->connector = drm_connector_index(connector);
+	req->num_properties = num_properties;
+
+	num_properties = gud_drm_connector_fill_properties(connector, connector_state,
+							   req->properties);
+
+	for (i = 0; i < gdrm->num_properties; i++) {
+		u16 prop = gdrm->properties[i];
+		u64 val;
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_ROTATION:
+			val = new_plane_state->rotation;
+			break;
+		default:
+			WARN_ON_ONCE(1);
+			ret = -EINVAL;
+			goto out;
+		}
+
+		req->properties[num_properties + i].prop = cpu_to_le16(prop);
+		req->properties[num_properties + i].val = cpu_to_le64(val);
+	}
+
+	if (!drm_dev_enter(fb->dev, &idx)) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	ret = gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_STATE_CHECK, 0, req, len);
+
+	drm_dev_exit(idx);
+out:
+	kfree(req);
+
+	return ret;
+}
+
+void gud_drm_pipe_update(struct drm_simple_display_pipe *pipe,
+			 struct drm_plane_state *old_state)
+{
+	struct drm_device *drm = pipe->crtc.dev;
+	struct gud_drm_device *gdrm = to_gud_drm_device(drm);
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_framebuffer *fb = state->fb;
+	struct drm_crtc *crtc = &pipe->crtc;
+	struct drm_rect damage;
+	int idx;
+
+	if (!drm_dev_enter(drm, &idx))
+		return;
+
+	if (!old_state->fb)
+		gud_drm_usb_write8(gdrm, GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE, 1);
+
+	if (fb && (crtc->state->mode_changed || crtc->state->connectors_changed))
+		gud_drm_usb_set(gdrm, GUD_DRM_USB_REQ_SET_STATE_COMMIT, 0, NULL, 0);
+
+	if (crtc->state->active_changed)
+		gud_drm_usb_write8(gdrm, GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE, crtc->state->active);
+
+	if (drm_atomic_helper_damage_merged(old_state, state, &damage))
+		gud_drm_fb_queue_damage(gdrm, fb, &damage);
+
+	if (!fb) {
+		cancel_work_sync(&gdrm->work);
+
+		mutex_lock(&gdrm->damage_lock);
+		if (gdrm->fb) {
+			drm_framebuffer_put(gdrm->fb);
+			gdrm->fb = NULL;
+		}
+		gud_drm_clear_damage(gdrm);
+		mutex_unlock(&gdrm->damage_lock);
+
+		gud_drm_usb_write8(gdrm, GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE, 0);
+	}
+
+	drm_dev_exit(idx);
+}
diff --git a/include/drm/gud_drm.h b/include/drm/gud_drm.h
new file mode 100644
index 000000000000..36d35bc7cff2
--- /dev/null
+++ b/include/drm/gud_drm.h
@@ -0,0 +1,364 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#ifndef __LINUX_GUD_DRM_H
+#define __LINUX_GUD_DRM_H
+
+#include <drm/drm_modes.h>
+#include <linux/types.h>
+#include <uapi/drm/drm_fourcc.h>
+#include <uapi/linux/usb/ch9.h>
+
+/*
+ * Maximum size of a control message, fits 120 display modes.
+ * If this needs to increase, the IN side in f_gud_drm_setup()
+ * needs fixing.
+ */
+#define GUD_DRM_MAX_TRANSFER_SIZE	SZ_4K
+
+#define GUD_DRM_USB_DT_DISPLAY		(USB_TYPE_VENDOR | 0x4)
+
+/*
+ * struct gud_drm_display_descriptor - Display descriptor
+ * @bLength: Size of descriptor in bytes
+ * @bDescriptorType: DescriptorType (GUD_DRM_USB_DT_DISPLAY)
+ * @bVersion: Protocol version
+ * @bMaxBufferSizeOrder: Maximum buffer size the device can handle as log2
+ * @bmFlags: Currently unused, should be set to zero
+ * @bCompression: Supported compression types
+ * @dwMinWidth: Minimum pixel width the controller can handle
+ * @dwMaxWidth: Maximum width
+ * @dwMinHeight: Minimum height
+ * @dwMaxHeight: Maximum height
+ * @bNumFormats: Number of supported pixel formats
+ * @bNumProperties: Number of properties that are not connector porperties
+ * @bNumConnectors: Number of connectors
+ *
+ * Devices that have only one display mode will have dwMinWidth == dwMaxWidth
+ * and dwMinHeight == dwMaxHeight.
+ *
+ */
+struct gud_drm_display_descriptor {
+	__u8 bLength;
+	__u8 bDescriptorType;
+
+	__u8 bVersion;
+	__u8 bMaxBufferSizeOrder;
+	__le32 bmFlags;
+
+	__u8 bCompression;
+#define GUD_DRM_COMPRESSION_LZ4		BIT(0)
+
+	__le32 dwMinWidth;
+	__le32 dwMaxWidth;
+	__le32 dwMinHeight;
+	__le32 dwMaxHeight;
+
+	__u8 bNumFormats;
+	__u8 bNumProperties;
+	__u8 bNumConnectors;
+} __packed;
+
+/*
+ * struct gud_drm_req_get_status - Status request
+ * @flags: Flags
+ * @errno: Linux errno value
+ *
+ * The host keeps polling for status as long as the GUD_DRM_STATUS_PENDING flag
+ * is set (or until timeout). Requested using: USB_REQ_GET_STATUS.
+ */
+struct gud_drm_req_get_status {
+	__u8 flags;
+#define GUD_DRM_STATUS_PENDING	BIT(0)
+	__u8 errno;
+} __packed;
+
+/*
+ * struct gud_drm_property - Property
+ * @prop: Property
+ * @val: Value
+ */
+struct gud_drm_property {
+	__le16 prop;
+	__le64 val;
+} __packed;
+
+/* See &drm_display_mode for the meaning of these fields */
+struct gud_drm_display_mode {
+	__le32 clock;
+	__le16 hdisplay;
+	__le16 hsync_start;
+	__le16 hsync_end;
+	__le16 htotal;
+	__le16 hskew;
+	__le16 vdisplay;
+	__le16 vsync_start;
+	__le16 vsync_end;
+	__le16 vtotal;
+	__le16 vscan;
+	__le32 vrefresh;
+	__le32 flags;
+	__u8 type;
+} __packed;
+
+/*
+ * struct gud_drm_req_get_connector - Connector descriptor
+ * @connector_type: Connector type (DRM_MODE_CONNECTOR_*)
+ * @flags: Flags
+ * @num_properties: Number of supported properties
+ */
+struct gud_drm_req_get_connector {
+	__u8 connector_type;
+
+	__le32 flags;
+#define GUD_DRM_CONNECTOR_FLAGS_POLL	BIT(0)
+
+	__u8 num_properties;
+} __packed;
+
+/*
+ * struct gud_drm_req_get_connector_status - Connector status
+ * @status: Status, see &drm_connector_status
+ * @num_modes: Number of available display modes
+ * @modes_array_checksum: CRC-CCITT checksum of the display mode array in little endian format
+ * @edid_len: Length of EDID data
+ * @edid_checksum: CRC-CCITT checksum of EDID data
+ *
+ * If both @num_modes and @edid_len are zero, connector status is set to
+ * disconnected. If @num_modes is zero, edid is used to create display modes.
+ * If both are set, edid is just passed on to userspace in the EDID connector
+ * property.
+ *
+ * Display modes and EDID are only requested if number/length or crc differs.
+ */
+struct gud_drm_req_get_connector_status {
+	__u8 status;
+#define GUD_DRM_CONNECTOR_STATUS_MASK		0xf /* Only 2 bits are currently used for status */
+#define GUD_DRM_CONNECTOR_STATUS_CHANGED	BIT(7)
+	__u16 num_modes;
+	__u16 edid_len;
+} __packed;
+
+/*
+ * struct gud_drm_req_set_buffer - Set buffer transfer info
+ * @x: X position of rectangle
+ * @y: Y position
+ * @width: Pixel width of rectangle
+ * @height: Pixel height
+ * @length: Buffer length in bytes
+ * @compression: Transfer compression
+ * @compressed_length: Compressed buffer length
+ *
+ * @x, @y, @width and @height specifies the rectangle where the buffer should be
+ * placed inside the framebuffer.
+ */
+struct gud_drm_req_set_buffer {
+	__le32 x;
+	__le32 y;
+	__le32 width;
+	__le32 height;
+
+	__le32 length;
+	__u8 compression;
+	__le32 compressed_length;
+} __packed;
+
+/*
+ * struct gud_drm_req_set_state - Set display state
+ * @mode: Display mode
+ * @format: Pixel format
+ * @connector: Connector index
+ * @num_properties: Number of properties in the state
+ * @properties: Array of properties
+ *
+ * The entire state is transferred each time there's a change.
+ */
+struct gud_drm_req_set_state {
+	struct gud_drm_display_mode mode;
+	__le32 format;
+	__u8 connector;
+	__u8 num_properties;
+	struct gud_drm_property properties[];
+} __packed;
+
+/*
+ * Internal monochrome transfer format presented to userspace as XRGB8888.
+ * Pixel lines are byte aligned.
+ */
+#define GUD_DRM_FORMAT_R1	fourcc_code('R', '1', ' ', ' ')
+
+/* List of supported connector properties: */
+
+/* TV related properties, see &drm_connector and &drm_tv_connector_state */
+#define GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR		1
+#define GUD_DRM_PROPERTY_TV_LEFT_MARGIN			2
+#define GUD_DRM_PROPERTY_TV_RIGHT_MARGIN		3
+#define GUD_DRM_PROPERTY_TV_TOP_MARGIN			4
+#define GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN		5
+/* Number of modes are placed at _SHIFT in val on retrieval */
+#define GUD_DRM_PROPERTY_TV_MODE			6
+  #define GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT   16
+#define GUD_DRM_PROPERTY_TV_BRIGHTNESS			7
+#define GUD_DRM_PROPERTY_TV_CONTRAST			8
+#define GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION		9
+#define GUD_DRM_PROPERTY_TV_OVERSCAN			10
+#define GUD_DRM_PROPERTY_TV_SATURATION			11
+#define GUD_DRM_PROPERTY_TV_HUE				12
+
+/*
+ * Backlight brightness is in the range 0-100 inclusive. The value represents
+ * the human perceptual brightness and not a linear PWM value. 0 is minimum
+ * brightness which should not turn the backlight completely off. The DPMS
+ * connector property should be used to control power which will trigger a
+ * GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE request.
+ *
+ * This is not a real DRM property, but rather a fake one used for the backlight
+ * device. See drm_backlight_register() for more details.
+ */
+#define GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS		13
+
+/* List of supported properties that are not connector propeties: */
+
+/*
+ * Plane rotation. Should return the supported bitmask on
+ * GUD_DRM_USB_REQ_GET_PROPERTIES, see drm_plane_create_rotation_property().
+ */
+#define GUD_DRM_PROPERTY_ROTATION			50
+
+/* USB Control requests: */
+
+/*
+ * If the host driver doesn't support the device protocol version it will send
+ * its version (u8). If the device isn't backwards compatible or doesn't support
+ * the host version it shall halt the transfer. There is no status request
+ * issued if this request fails/halts.
+ */
+#define GUD_DRM_USB_REQ_SET_VERSION			0x30
+
+/* Get supported pixel formats as an array of fourcc codes. See include/uapi/drm/drm_fourcc.h */
+#define GUD_DRM_USB_REQ_GET_FORMATS			0x40
+
+/* Get supported properties that are not connector propeties as a &gud_drm_property array */
+#define GUD_DRM_USB_REQ_GET_PROPERTIES			0x41
+
+/* Get connector descriptor */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR			0x50
+
+/* Get properties supported by the connector as a &gud_drm_property array */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_PROPERTIES	0x51
+
+/*
+ * Issued when there's a tv.mode property present.
+ * Gets an array of tv.mode enum names each entry of length DRM_PROP_NAME_LEN.
+ */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_TV_MODE_VALUES	0x52
+
+/* When userspace checks status, this is issued first, not used for poll requests. */
+#define GUD_DRM_USB_REQ_SET_CONNECTOR_FORCE_DETECT	0x53
+
+/* Get connector status as &gud_drm_req_get_connector_status. */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_STATUS		0x54
+
+/* Get &gud_drm_display_mode array of supported display modes */
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_MODES		0x55
+
+#define GUD_DRM_USB_REQ_GET_CONNECTOR_EDID		0x56
+
+/* Set buffer properties before bulk transfer as &gud_drm_req_set_buffer */
+#define GUD_DRM_USB_REQ_SET_BUFFER			0x60
+
+/* Check display configuration as &gud_drm_req_set_state */
+#define GUD_DRM_USB_REQ_SET_STATE_CHECK			0x61
+
+/* Apply the prevoius _STATE_CHECK configuration */
+#define GUD_DRM_USB_REQ_SET_STATE_COMMIT		0x62
+
+ /* Enable/disable the display controller, value is u8 0/1 */
+#define GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE		0x63
+
+/* Enable/disable display/output (DPMS), value is u8 0/1 */
+#define GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE		0x64
+
+static inline void gud_drm_from_display_mode(struct gud_drm_display_mode *dst,
+					     const struct drm_display_mode *src)
+{
+	u32 flags = src->flags;
+
+	switch (src->picture_aspect_ratio) {
+	case HDMI_PICTURE_ASPECT_4_3:
+		flags |= DRM_MODE_FLAG_PIC_AR_4_3;
+		break;
+	case HDMI_PICTURE_ASPECT_16_9:
+		flags |= DRM_MODE_FLAG_PIC_AR_16_9;
+		break;
+	case HDMI_PICTURE_ASPECT_64_27:
+		flags |= DRM_MODE_FLAG_PIC_AR_64_27;
+		break;
+	case HDMI_PICTURE_ASPECT_256_135:
+		flags |= DRM_MODE_FLAG_PIC_AR_256_135;
+		break;
+	default:
+		flags |= DRM_MODE_FLAG_PIC_AR_NONE;
+		break;
+	}
+
+	dst->clock = cpu_to_le32(src->clock);
+	dst->hdisplay = cpu_to_le16(src->hdisplay);
+	dst->hsync_start = cpu_to_le16(src->hsync_start);
+	dst->hsync_end = cpu_to_le16(src->hsync_end);
+	dst->htotal = cpu_to_le16(src->htotal);
+	dst->hskew = cpu_to_le16(src->hskew);
+	dst->vdisplay = cpu_to_le16(src->vdisplay);
+	dst->vsync_start = cpu_to_le16(src->vsync_start);
+	dst->vsync_end = cpu_to_le16(src->vsync_end);
+	dst->vtotal = cpu_to_le16(src->vtotal);
+	dst->vscan = cpu_to_le16(src->vscan);
+	dst->vrefresh = cpu_to_le32(src->vrefresh);
+	dst->flags = cpu_to_le32(flags);
+	dst->type = src->type;
+}
+
+static inline void gud_drm_to_display_mode(struct drm_display_mode *dst,
+					   const struct gud_drm_display_mode *src)
+{
+	u32 flags = le32_to_cpu(src->flags);
+
+	dst->clock = le32_to_cpu(src->clock);
+	dst->hdisplay = le16_to_cpu(src->hdisplay);
+	dst->hsync_start = le16_to_cpu(src->hsync_start);
+	dst->hsync_end = le16_to_cpu(src->hsync_end);
+	dst->htotal = le16_to_cpu(src->htotal);
+	dst->hskew = le16_to_cpu(src->hskew);
+	dst->vdisplay = le16_to_cpu(src->vdisplay);
+	dst->vsync_start = le16_to_cpu(src->vsync_start);
+	dst->vsync_end = le16_to_cpu(src->vsync_end);
+	dst->vtotal = le16_to_cpu(src->vtotal);
+	dst->vscan = le16_to_cpu(src->vscan);
+	dst->vrefresh = le32_to_cpu(src->vrefresh);
+	dst->flags = flags & ~DRM_MODE_FLAG_PIC_AR_MASK;
+	dst->type = src->type;
+
+	switch (flags & DRM_MODE_FLAG_PIC_AR_MASK) {
+	case DRM_MODE_FLAG_PIC_AR_4_3:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_4_3;
+		break;
+	case DRM_MODE_FLAG_PIC_AR_16_9:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_16_9;
+		break;
+	case DRM_MODE_FLAG_PIC_AR_64_27:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_64_27;
+		break;
+	case DRM_MODE_FLAG_PIC_AR_256_135:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_256_135;
+		break;
+	default:
+		dst->picture_aspect_ratio = HDMI_PICTURE_ASPECT_NONE;
+		break;
+	}
+
+	drm_mode_set_name(dst);
+}
+
+#endif
-- 
2.23.0

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

[PATCH v2 09/10] drm/gud: Add functionality for the USB gadget side

[Noralf Trønnes]

Since the USB gadget/device has to reach into the DRM internals, part of
the code is placed in the DRM subsystem as a separate module. All calls
into this module runs in process context and are serialized, except one
function that runs in interrupt context.

Since both the gadget side and the DRM side can disable the gadget,
special care has been taken to make that safe.

v2:
- Use drm_client_modeset_disable()

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/gud/Kconfig          |    6 +
 drivers/gpu/drm/gud/Makefile         |    1 +
 drivers/gpu/drm/gud/gud_drm_gadget.c | 1165 ++++++++++++++++++++++++++
 include/drm/gud_drm.h                |   13 +
 4 files changed, 1185 insertions(+)
 create mode 100644 drivers/gpu/drm/gud/gud_drm_gadget.c

diff --git a/drivers/gpu/drm/gud/Kconfig b/drivers/gpu/drm/gud/Kconfig
index 767f1c067ed9..9bbf39ae6191 100644
--- a/drivers/gpu/drm/gud/Kconfig
+++ b/drivers/gpu/drm/gud/Kconfig
@@ -12,3 +12,9 @@ config DRM_GUD
 	  adapters.
 
 	  If M is selected the module will be called gud_drm.
+
+config DRM_GUD_GADGET
+	tristate
+	depends on DRM
+	select LZ4_DECOMPRESS
+	select BACKLIGHT_CLASS_DEVICE
diff --git a/drivers/gpu/drm/gud/Makefile b/drivers/gpu/drm/gud/Makefile
index 73ed7ef3da94..fb5cfbd93d0f 100644
--- a/drivers/gpu/drm/gud/Makefile
+++ b/drivers/gpu/drm/gud/Makefile
@@ -2,3 +2,4 @@
 
 gud_drm-objs			:= gud_drm_drv.o gud_drm_pipe.o gud_drm_connector.o
 obj-$(CONFIG_DRM_GUD)		+= gud_drm.o
+obj-$(CONFIG_DRM_GUD_GADGET)	+= gud_drm_gadget.o
diff --git a/drivers/gpu/drm/gud/gud_drm_gadget.c b/drivers/gpu/drm/gud/gud_drm_gadget.c
new file mode 100644
index 000000000000..6bc438634ed3
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_gadget.c
@@ -0,0 +1,1165 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/lz4.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+#include <drm/drm_client.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_mode_object.h>
+#include <drm/drm_plane.h>
+#include <drm/drm_rect.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+/*
+ * Concurrency:
+ * Calls into this module from f_gud_drm are serialized and run in process
+ * context except gud_drm_gadget_ctrl_get() which is run in interrupt context.
+ *
+ * Termination:
+ * A DRM client can not release itself, only the DRM driver which resources the
+ * client uses can do that.
+ * This means that there are 2 paths to stop the gadget function:
+ * - Unregistering the DRM driver (module unload)
+ * - Disabling the USB gadget (configfs unbind)
+ *
+ * A use counter protects the gadget should the client go away. A kref is used
+ * to control the release of the gud_drm_gadget structure shared by the 2 actors.
+ *
+ * Backlight:
+ * If there's a backlight device it's attached to the first connector.
+ */
+
+struct gud_drm_gadget_connector {
+	struct drm_connector *connector;
+
+	const struct gud_drm_property *properties;
+	unsigned int num_properties;
+	const char *tv_mode_enum_names;
+	unsigned int num_tv_mode_enum_names;
+	struct backlight_device *backlight;
+
+	spinlock_t lock; /* Protects the following members: */
+	enum drm_connector_status status;
+	unsigned int width_mm;
+	unsigned int height_mm;
+	struct gud_drm_display_mode *modes;
+	unsigned int num_modes;
+	void *edid;
+	size_t edid_len;
+	bool changed;
+};
+
+struct gud_drm_gadget {
+	struct kref refcount;
+	refcount_t usecnt;
+	struct drm_client_dev client;
+	struct backlight_device *backlight;
+
+	const u32 *formats;
+	unsigned int format_count;
+
+	const struct gud_drm_property *properties;
+	unsigned int num_properties;
+
+	struct gud_drm_gadget_connector *connectors;
+	unsigned int connector_count;
+
+	struct drm_rect set_buffer_rect;
+	u32 set_buffer_length;
+	u8 set_buffer_compression;
+	u32 set_buffer_compressed_length;
+
+	struct drm_client_buffer *buffer;
+	struct drm_client_buffer *buffer_check;
+	u8 brightness;
+	bool check_ok;
+
+	size_t max_buffer_size;
+	void *work_buf;
+};
+
+static int gud_drm_gadget_probe_connector(struct gud_drm_gadget_connector *gconn)
+{
+	struct drm_connector *connector = gconn->connector;
+	struct gud_drm_display_mode *modes = NULL;
+	struct drm_device *drm = connector->dev;
+	struct drm_display_mode *mode;
+	void *edid_data, *edid = NULL;
+	unsigned int num_modes = 0;
+	size_t edid_len = 0;
+	unsigned long flags;
+	unsigned int i = 0;
+	int ret = 0;
+
+	mutex_lock(&drm->mode_config.mutex);
+
+	connector->funcs->fill_modes(connector,
+				     drm->mode_config.max_width,
+				     drm->mode_config.max_height);
+
+	list_for_each_entry(mode, &connector->modes, head)
+		num_modes++;
+
+	if (!num_modes)
+		goto update;
+
+	modes = kmalloc_array(num_modes, sizeof(*modes), GFP_KERNEL);
+	if (!modes) {
+		ret = -ENOMEM;
+		num_modes = 0;
+		goto update;
+	}
+
+	list_for_each_entry(mode, &connector->modes, head)
+		gud_drm_from_display_mode(&modes[i++], mode);
+
+	if (!connector->edid_blob_ptr)
+		goto update;
+
+	edid_data = connector->edid_blob_ptr->data;
+	edid_len = connector->edid_blob_ptr->length;
+	if (!edid_data || !edid_len) {
+		edid_len = 0;
+		goto update;
+	}
+
+	edid = kmemdup(edid_data, edid_len, GFP_KERNEL);
+	if (!edid) {
+		ret = -ENOMEM;
+		edid_len = 0;
+	}
+
+update:
+	spin_lock_irqsave(&gconn->lock, flags);
+	if (gconn->status != connector->status || gconn->num_modes != num_modes ||
+	    gconn->edid_len != edid_len ||
+	    (gconn->modes && modes && memcmp(gconn->modes, modes, num_modes * sizeof(*modes))) ||
+	    (gconn->edid && edid && memcmp(gconn->edid, edid, edid_len)))
+		gconn->changed = true;
+	swap(gconn->modes, modes);
+	gconn->num_modes = num_modes;
+	swap(gconn->edid, edid);
+	gconn->edid_len = edid_len;
+	gconn->width_mm = connector->display_info.width_mm;
+	gconn->height_mm = connector->display_info.height_mm;
+	gconn->status = connector->status;
+	spin_unlock_irqrestore(&gconn->lock, flags);
+
+	mutex_unlock(&drm->mode_config.mutex);
+
+	kfree(edid);
+	kfree(modes);
+
+	return ret;
+}
+
+static void gud_drm_gadget_probe_connectors(struct gud_drm_gadget *gdg)
+{
+	unsigned int i;
+
+	for (i = 0; i < gdg->connector_count; i++)
+		gud_drm_gadget_probe_connector(&gdg->connectors[i]);
+}
+
+static bool gud_drm_gadget_check_buffer(struct gud_drm_gadget *gdg,
+					struct drm_client_buffer *buffer,
+					struct drm_display_mode *mode,
+					u32 format)
+{
+	struct drm_framebuffer *fb;
+
+	if (!buffer)
+		return false;
+
+	fb = buffer->fb;
+
+	return fb->format->format == format &&
+	       fb->width == mode->hdisplay && fb->height == mode->vdisplay;
+}
+
+static bool gud_drm_gadget_set_connector_property(struct drm_client_dev *client,
+						  struct drm_connector *connector,
+						  u16 prop, u64 val, int *ret)
+{
+	struct drm_mode_config *config = &connector->dev->mode_config;
+	struct drm_property *property;
+
+	switch (prop) {
+	case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+		property = config->tv_select_subconnector_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+		property = config->tv_left_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+		property = config->tv_right_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+		property = config->tv_top_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+		property = config->tv_bottom_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_MODE:
+		property = config->tv_mode_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+		property = config->tv_brightness_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_CONTRAST:
+		property = config->tv_contrast_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+		property = config->tv_flicker_reduction_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_OVERSCAN:
+		property = config->tv_overscan_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_SATURATION:
+		property = config->tv_saturation_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_HUE:
+		property = config->tv_hue_property;
+		break;
+	default:
+		return false;
+	}
+
+	*ret = drm_client_modeset_set_property(client, &connector->base, property, val);
+
+	return true;
+}
+
+static int gud_drm_gadget_check(struct gud_drm_gadget *gdg, struct gud_drm_req_set_state *req,
+				size_t size)
+{
+	struct drm_client_dev *client = &gdg->client;
+	u32 format = le32_to_cpu(req->format);
+	struct drm_client_buffer *buffer;
+	struct drm_connector *connector;
+	struct drm_display_mode mode;
+	unsigned int i;
+	void *vaddr;
+	int ret;
+
+	if (size < sizeof(struct gud_drm_req_set_state))
+		return -EINVAL;
+
+	if (size != struct_size(req, properties, req->num_properties))
+		return -EINVAL;
+
+	memset(&mode, 0, sizeof(mode));
+	gud_drm_to_display_mode(&mode, &req->mode);
+
+	gdg->check_ok = false;
+
+	if (!mode.hdisplay || !format)
+		return -EINVAL;
+
+	if (req->connector >= gdg->connector_count)
+		return -EINVAL;
+
+	connector = gdg->connectors[req->connector].connector;
+
+	if (gdg->buffer_check) {
+		drm_client_framebuffer_delete(gdg->buffer_check);
+		gdg->buffer_check = NULL;
+	}
+
+	if (!gud_drm_gadget_check_buffer(gdg, gdg->buffer, &mode, format)) {
+		buffer = drm_client_framebuffer_create(client, mode.hdisplay, mode.vdisplay,
+						       format);
+		if (IS_ERR(buffer))
+			return PTR_ERR(buffer);
+
+		vaddr = drm_client_buffer_vmap(buffer);
+		if (IS_ERR(vaddr)) {
+			drm_client_framebuffer_delete(buffer);
+			return PTR_ERR(vaddr);
+		}
+
+		gdg->buffer_check = buffer;
+	} else {
+		buffer = gdg->buffer;
+	}
+
+	ret = drm_client_modeset_set(client, connector, &mode, buffer->fb);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < req->num_properties; i++) {
+		u16 prop = le16_to_cpu(req->properties[i].prop);
+		u64 val = le64_to_cpu(req->properties[i].val);
+
+		if (gud_drm_gadget_set_connector_property(client, connector, prop, val, &ret)) {
+			if (ret)
+				return ret;
+			continue;
+		}
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS:
+			if (val > 100)
+				return -EINVAL;
+			gdg->brightness = val;
+			break;
+		case GUD_DRM_PROPERTY_ROTATION:
+			ret = drm_client_modeset_set_rotation(client, val);
+			break;
+		default:
+			pr_err("%s: Unknown property: %u\n", __func__, prop);
+			continue;
+		}
+
+		if (ret)
+			return ret;
+	}
+
+	ret = drm_client_modeset_check(&gdg->client);
+	if (ret)
+		return ret;
+
+	gdg->check_ok = true;
+
+	return 0;
+}
+
+static int gud_drm_gadget_commit(struct gud_drm_gadget *gdg)
+{
+	int ret;
+
+	if (!gdg->check_ok)
+		return -EINVAL;
+
+	if (gdg->backlight) {
+		int val, max_brightness = gdg->backlight->props.max_brightness;
+
+		val = DIV64_U64_ROUND_UP(gdg->brightness * max_brightness, 100);
+		ret = backlight_device_set_brightness(gdg->backlight, val);
+		if (ret)
+			return ret;
+	}
+
+	ret = drm_client_modeset_commit(&gdg->client);
+	if (ret)
+		return ret;
+
+	if (gdg->buffer_check) {
+		drm_client_framebuffer_delete(gdg->buffer);
+		gdg->buffer = gdg->buffer_check;
+		gdg->buffer_check = NULL;
+	}
+
+	return 0;
+}
+
+static size_t gud_drm_gadget_write_buffer_memcpy(struct drm_client_buffer *buffer,
+						 const void *src, size_t len,
+						 struct drm_rect *rect)
+{
+	unsigned int cpp = buffer->fb->format->cpp[0];
+	size_t dst_pitch = buffer->fb->pitches[0];
+	size_t src_pitch = drm_rect_width(rect) * cpp;
+	unsigned int y;
+	void *dst;
+
+	/* Get the address, it's already mapped */
+	dst = drm_client_buffer_vmap(buffer);
+	dst += rect->y1 * dst_pitch;
+	dst += rect->x1 * cpp;
+
+	for (y = 0; y < drm_rect_height(rect) && len; y++) {
+		src_pitch = min(src_pitch, len);
+		memcpy(dst, src, src_pitch);
+		src += src_pitch;
+		dst += dst_pitch;
+		len -= src_pitch;
+	}
+
+	return len;
+}
+
+static bool gud_drm_gadget_check_rect(struct drm_client_buffer *buffer, struct drm_rect *rect)
+{
+	return buffer->fb && rect->x1 < rect->x2 && rect->y1 < rect->y2 &&
+	       rect->x2 <= buffer->fb->width && rect->y2 <= buffer->fb->height;
+}
+
+int gud_drm_gadget_write_buffer(struct gud_drm_gadget *gdg, const void *buf, size_t len)
+{
+	struct drm_client_buffer *buffer = gdg->buffer ? gdg->buffer : gdg->buffer_check;
+	struct drm_rect *rect = &gdg->set_buffer_rect;
+	u8 compression = gdg->set_buffer_compression;
+	struct drm_framebuffer *fb;
+	size_t remain;
+	int ret;
+
+	pr_debug("%s: len=%zu compression=0x%x\n", __func__, len, compression);
+
+	if (WARN_ON_ONCE(!buffer))
+		return -ENOMEM;
+
+	if (!gud_drm_gadget_check_rect(buffer, rect)) {
+		pr_err("%s: Rectangle doesn't fit\n", __func__);
+		return -EINVAL;
+	}
+
+	fb = buffer->fb;
+
+	if (compression & GUD_DRM_COMPRESSION_LZ4) {
+		if (len != gdg->set_buffer_compressed_length) {
+			pr_err("%s: Buffer compressed len differs: %zu != %zu\n",
+			       __func__, len, gdg->set_buffer_compressed_length);
+			return -EINVAL;
+		}
+
+		ret = LZ4_decompress_safe(buf, gdg->work_buf, len, gdg->max_buffer_size);
+		if (ret < 0) {
+			pr_err("%s: Failed to decompress buffer\n", __func__);
+			return -EIO;
+		}
+
+		buf = gdg->work_buf;
+		len = ret;
+	}
+
+	if (len != gdg->set_buffer_length) {
+		pr_err("%s: Buffer len differs: %zu != %zu\n",
+		       __func__, len, gdg->set_buffer_length);
+		return -EINVAL;
+	}
+
+	if (len > (drm_rect_width(rect) * drm_rect_height(rect) * fb->format->cpp[0])) {
+		pr_err("%s: Buffer is too big for rectangle\n", __func__);
+		return -EINVAL;
+	}
+
+	remain = gud_drm_gadget_write_buffer_memcpy(buffer, buf, len, rect);
+	if (remain) {
+		pr_err("%s: Failed to write buffer: remain=%zu\n", __func__, remain);
+		return -EIO;
+	}
+
+	return drm_client_framebuffer_flush(buffer, rect);
+}
+EXPORT_SYMBOL(gud_drm_gadget_write_buffer);
+
+int gud_drm_gadget_set_buffer(struct gud_drm_gadget *gdg, struct gud_drm_req_set_buffer *req)
+{
+	u32 compressed_length = le32_to_cpu(req->compressed_length);
+	u32 length = le32_to_cpu(req->length);
+	struct drm_client_buffer *buffer;
+	struct drm_rect rect;
+	int ret = 0;
+
+	if (!refcount_inc_not_zero(&gdg->usecnt))
+		return -ENODEV;
+
+	buffer = gdg->buffer ? gdg->buffer : gdg->buffer_check;
+	if (!buffer) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	drm_rect_init(&rect, le32_to_cpu(req->x), le32_to_cpu(req->y),
+		      le32_to_cpu(req->width), le32_to_cpu(req->height));
+
+	pr_debug("%s: " DRM_RECT_FMT "\n", __func__, DRM_RECT_ARG(&rect));
+
+	if (!gud_drm_gadget_check_rect(buffer, &rect)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (req->compression & ~GUD_DRM_COMPRESSION_LZ4) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	gdg->set_buffer_rect = rect;
+	gdg->set_buffer_length = length;
+
+	if (req->compression) {
+		if (!compressed_length) {
+			ret = -EINVAL;
+			goto out;
+		}
+		gdg->set_buffer_compression = req->compression;
+		gdg->set_buffer_compressed_length = compressed_length;
+		length = compressed_length;
+	} else {
+		gdg->set_buffer_compression = 0;
+		gdg->set_buffer_compressed_length = 0;
+	}
+out:
+	refcount_dec(&gdg->usecnt);
+
+	return ret ? ret : length;
+}
+EXPORT_SYMBOL(gud_drm_gadget_set_buffer);
+
+static void gud_drm_gadget_delete_buffers(struct gud_drm_gadget *gdg)
+{
+	drm_client_framebuffer_delete(gdg->buffer_check);
+	drm_client_framebuffer_delete(gdg->buffer);
+	gdg->buffer_check = NULL;
+	gdg->buffer = NULL;
+}
+
+int gud_drm_gadget_disable_pipe(struct gud_drm_gadget *gdg)
+{
+	int ret;
+
+	ret = drm_client_modeset_disable(&gdg->client);
+	gud_drm_gadget_delete_buffers(gdg);
+
+	return ret;
+}
+EXPORT_SYMBOL(gud_drm_gadget_disable_pipe);
+
+static int gud_drm_gadget_ctrl_get_display_descriptor(struct gud_drm_gadget *gdg, u16 value,
+						      void *data, size_t size)
+{
+	struct drm_device *drm = gdg->client.dev;
+	struct gud_drm_display_descriptor desc;
+	u8 type = value >> 8;
+	u8 index = value & 0xff;
+
+	if (type != GUD_DRM_USB_DT_DISPLAY || index)
+		return -EINVAL;
+
+	desc.bLength = sizeof(desc);
+	desc.bDescriptorType = GUD_DRM_USB_DT_DISPLAY;
+
+	desc.bVersion = 1;
+	desc.bMaxBufferSizeOrder = ilog2(gdg->max_buffer_size);
+	desc.bmFlags = 0;
+	desc.bCompression = GUD_DRM_COMPRESSION_LZ4;
+
+	desc.dwMinWidth = cpu_to_le32(drm->mode_config.min_width);
+	desc.dwMaxWidth = cpu_to_le32(drm->mode_config.max_width);
+	desc.dwMinHeight = cpu_to_le32(drm->mode_config.min_height);
+	desc.dwMaxHeight = cpu_to_le32(drm->mode_config.max_height);
+	desc.bNumFormats = gdg->format_count;
+	desc.bNumProperties = gdg->num_properties;
+	desc.bNumConnectors = gdg->connector_count;
+
+	size = min(size, sizeof(desc));
+	memcpy(data, &desc, size);
+
+	return size;
+}
+
+static void gud_drm_gadget_ctrl_get_formats(struct gud_drm_gadget *gdg, __le32 *formats)
+{
+	unsigned int i;
+
+	for (i = 0; i < gdg->format_count; i++)
+		formats[i] = cpu_to_le32(gdg->formats[i]);
+}
+
+static int gud_drm_gadget_ctrl_get_connector(struct gud_drm_gadget *gdg, unsigned int index,
+					     struct gud_drm_req_get_connector *desc)
+{
+	struct gud_drm_gadget_connector *gconn;
+
+	if (index >= gdg->connector_count)
+		return -EINVAL;
+
+	memset(desc, 0, sizeof(*desc));
+
+	gconn = &gdg->connectors[index];
+
+	desc->connector_type = gconn->connector->connector_type;
+	desc->flags = cpu_to_le32(GUD_DRM_CONNECTOR_FLAGS_POLL);
+	desc->num_properties = gconn->num_properties;
+
+	return 0;
+}
+
+static struct gud_drm_gadget_connector *
+gud_drm_gadget_get_gconn(struct gud_drm_gadget *gdg, unsigned int index)
+{
+	if (index >= gdg->connector_count)
+		return NULL;
+
+	return &gdg->connectors[index];
+}
+
+static int gud_drm_gadget_ctrl_get_connector_status(struct gud_drm_gadget *gdg, unsigned int index,
+						    struct gud_drm_req_get_connector_status *status)
+{
+	struct gud_drm_gadget_connector *gconn;
+	unsigned long flags;
+
+	gconn = gud_drm_gadget_get_gconn(gdg, index);
+	if (!gconn)
+		return -ENOENT;
+
+	memset(status, 0, sizeof(*status));
+
+	spin_lock_irqsave(&gconn->lock, flags);
+	status->status = gconn->status;
+	if (gconn->changed) {
+		status->status |= GUD_DRM_CONNECTOR_STATUS_CHANGED;
+		gconn->changed = false;
+	}
+	if (gconn->num_modes)
+		status->num_modes = cpu_to_le16(gconn->num_modes);
+	if (gconn->edid_len)
+		status->edid_len = cpu_to_le16(gconn->edid_len);
+	spin_unlock_irqrestore(&gconn->lock, flags);
+
+	return 0;
+}
+
+/* This runs in interrupt context */
+int gud_drm_gadget_ctrl_get(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size)
+{
+	struct gud_drm_gadget_connector *gconn;
+	unsigned long flags;
+	int ret = -EINVAL;
+
+	pr_debug("%s: request=0x%x index=%u size=%zu\n", __func__, request, index, size);
+
+	if (!refcount_inc_not_zero(&gdg->usecnt))
+		return -ENODEV;
+
+	if (!size)
+		goto out;
+
+	switch (request) {
+	case USB_REQ_GET_DESCRIPTOR:
+		ret = gud_drm_gadget_ctrl_get_display_descriptor(gdg, index, data, size);
+		break;
+	case GUD_DRM_USB_REQ_GET_FORMATS:
+		if (!index && size == gdg->format_count * sizeof(u32)) {
+			gud_drm_gadget_ctrl_get_formats(gdg, data);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_PROPERTIES:
+		if (!index && size == gdg->num_properties * sizeof(*gdg->properties)) {
+			memcpy(data, gdg->properties, size);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR:
+		if (size == sizeof(struct gud_drm_req_get_connector))
+			ret = gud_drm_gadget_ctrl_get_connector(gdg, index, data);
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_PROPERTIES:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		if (gconn && size == gconn->num_properties * sizeof(*gconn->properties)) {
+			memcpy(data, gconn->properties, size);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_TV_MODE_VALUES:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		if (gconn && size == gconn->num_tv_mode_enum_names * DRM_PROP_NAME_LEN) {
+			memcpy(data, gconn->tv_mode_enum_names, size);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_STATUS:
+		if (size == sizeof(struct gud_drm_req_get_connector_status))
+			ret = gud_drm_gadget_ctrl_get_connector_status(gdg, index, data);
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_MODES:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		spin_lock_irqsave(&gconn->lock, flags);
+		if (gconn && size == gconn->num_modes * sizeof(*gconn->modes)) {
+			memcpy(data, gconn->modes, size);
+			ret = 0;
+		}
+		spin_unlock_irqrestore(&gconn->lock, flags);
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_EDID:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		spin_lock_irqsave(&gconn->lock, flags);
+		if (gconn && size == gconn->edid_len) {
+			memcpy(data, gconn->edid, size);
+			ret = 0;
+		}
+		spin_unlock_irqrestore(&gconn->lock, flags);
+		break;
+	}
+out:
+	refcount_dec(&gdg->usecnt);
+
+	return !ret ? size : ret;
+}
+EXPORT_SYMBOL(gud_drm_gadget_ctrl_get);
+
+int gud_drm_gadget_ctrl_set(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size)
+{
+	struct gud_drm_gadget_connector *gconn;
+	int dpms, ret = -EINVAL;
+
+	pr_debug("%s: request=0x%x index=%u size=%zu\n", __func__, request, index, size);
+
+	if (!refcount_inc_not_zero(&gdg->usecnt))
+		return -ENODEV;
+
+	switch (request) {
+	case GUD_DRM_USB_REQ_SET_CONNECTOR_FORCE_DETECT:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		if (gconn)
+			ret = gud_drm_gadget_probe_connector(gconn);
+		break;
+	case GUD_DRM_USB_REQ_SET_STATE_CHECK:
+		ret = gud_drm_gadget_check(gdg, data, size);
+		break;
+	case GUD_DRM_USB_REQ_SET_STATE_COMMIT:
+		if (!size)
+			ret = gud_drm_gadget_commit(gdg);
+		break;
+	case GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE:
+		if (size == sizeof(u8)) {
+			if (*(u8 *)data == 0)
+				ret = gud_drm_gadget_disable_pipe(gdg);
+			else
+				ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE:
+		if (size == sizeof(u8)) {
+			dpms = *(u8 *)data ? DRM_MODE_DPMS_ON : DRM_MODE_DPMS_OFF;
+			ret = drm_client_modeset_dpms(&gdg->client, dpms);
+		}
+		break;
+	}
+
+	refcount_dec(&gdg->usecnt);
+
+	return ret;
+}
+EXPORT_SYMBOL(gud_drm_gadget_ctrl_set);
+
+static int gud_drm_gadget_get_formats(struct gud_drm_gadget *gdg, u8 *max_cpp)
+{
+	struct drm_device *drm = gdg->client.dev;
+	struct drm_plane *plane;
+	unsigned int i;
+	u32 *formats;
+	int ret;
+
+	*max_cpp = 0;
+
+	drm_for_each_plane(plane, drm) {
+		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
+			break;
+	}
+
+	formats = kcalloc(plane->format_count, sizeof(u32), GFP_KERNEL);
+	if (!formats)
+		return -ENOMEM;
+
+	for (i = 0; i < plane->format_count; i++) {
+		const struct drm_format_info *fmt;
+
+		fmt = drm_format_info(plane->format_types[i]);
+		if (fmt->num_planes != 1)
+			continue;
+
+		/*
+		 * Supporting 24-bit bpp would add complexity so don't bother.
+		 * It's hardly used and compression removes much of the gain.
+		 */
+		if (fmt->cpp[0] == 3)
+			continue;
+
+		if (*max_cpp < fmt->cpp[0])
+			*max_cpp = fmt->cpp[0];
+
+		formats[gdg->format_count++] = plane->format_types[i];
+	}
+
+	if (!gdg->format_count) {
+		ret = -ENOENT;
+		goto err_free;
+	}
+
+	gdg->formats = formats;
+
+	return 0;
+
+err_free:
+	kfree(formats);
+
+	return ret;
+}
+
+static int gud_drm_gadget_get_rotation_property(struct drm_device *drm, u16 *prop, u64 *val)
+{
+	struct drm_property_enum *prop_enum;
+	struct drm_plane *plane;
+	unsigned int num_props = 0;
+	u16 bitmask = 0;
+
+	drm_for_each_plane(plane, drm) {
+		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
+			break;
+	}
+
+	if (!plane->rotation_property)
+		return 0;
+
+	list_for_each_entry(prop_enum, &plane->rotation_property->enum_list, head) {
+		num_props++;
+		bitmask |= BIT(prop_enum->value);
+	}
+
+	*prop = GUD_DRM_PROPERTY_ROTATION;
+	*val = bitmask;
+
+	return 1;
+}
+
+static int gud_drm_gadget_get_properties(struct gud_drm_gadget *gdg)
+{
+	struct gud_drm_property *properties;
+	u16 prop;
+	u64 val;
+	int ret;
+
+	ret = gud_drm_gadget_get_rotation_property(gdg->client.dev, &prop, &val);
+	if (ret <= 0)
+		return ret;
+
+	properties = kcalloc(1, sizeof(*properties), GFP_KERNEL);
+	if (!properties)
+		return -ENOMEM;
+
+	gdg->properties = properties;
+	gdg->num_properties++;
+
+	properties[0].prop = cpu_to_le16(prop);
+	properties[0].val = cpu_to_le64(val);
+
+	return 0;
+}
+
+static int gud_drm_gadget_get_connector_properties(struct gud_drm_gadget *gdg,
+						   struct gud_drm_gadget_connector *gconn)
+{
+	struct drm_device *drm = gdg->client.dev;
+	struct drm_mode_config *config = &drm->mode_config;
+	struct drm_connector *connector = gconn->connector;
+	struct drm_object_properties *conn_props = connector->base.properties;
+	struct gud_drm_property *properties;
+	unsigned int i, ret = 0;
+	u16 prop;
+	u64 val;
+
+	mutex_lock(&drm->mode_config.mutex);
+
+	if (!conn_props->count)
+		goto unlock;
+
+	/* Add room for possible backlight */
+	properties = kcalloc(conn_props->count + 1, sizeof(*properties), GFP_KERNEL);
+	if (!properties) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	gconn->properties = properties;
+
+	for (i = 0; i < conn_props->count; i++) {
+		struct drm_property *property = conn_props->properties[i];
+
+		if (property == config->tv_select_subconnector_property) {
+			prop = GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR;
+			val = connector->state->tv.subconnector;
+		} else if (property == config->tv_left_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_LEFT_MARGIN;
+			val = connector->state->tv.margins.left;
+		} else if (property == config->tv_right_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_RIGHT_MARGIN;
+			val = connector->state->tv.margins.right;
+		} else if (property == config->tv_top_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_TOP_MARGIN;
+			val = connector->state->tv.margins.top;
+		} else if (property == config->tv_bottom_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN;
+			val = connector->state->tv.margins.bottom;
+		} else if (property == config->tv_mode_property) {
+			struct drm_property_enum *prop_enum;
+			char *buf;
+
+			list_for_each_entry(prop_enum, &property->enum_list, head)
+				gconn->num_tv_mode_enum_names++;
+
+			if (WARN_ON(!gconn->num_tv_mode_enum_names)) {
+				ret = -EINVAL;
+				goto unlock;
+			}
+
+			buf = kcalloc(gconn->num_tv_mode_enum_names, DRM_PROP_NAME_LEN, GFP_KERNEL);
+			if (!buf) {
+				ret = -ENOMEM;
+				goto unlock;
+			}
+
+			gconn->tv_mode_enum_names = buf;
+
+			list_for_each_entry(prop_enum, &property->enum_list, head) {
+				strncpy(buf, prop_enum->name, DRM_PROP_NAME_LEN);
+				buf += DRM_PROP_NAME_LEN;
+			}
+
+			prop = GUD_DRM_PROPERTY_TV_MODE;
+			val = connector->state->tv.mode;
+			val |= gconn->num_tv_mode_enum_names << GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT;
+		} else if (property == config->tv_brightness_property) {
+			prop = GUD_DRM_PROPERTY_TV_BRIGHTNESS;
+			val = connector->state->tv.brightness;
+		} else if (property == config->tv_contrast_property) {
+			prop = GUD_DRM_PROPERTY_TV_CONTRAST;
+			val = connector->state->tv.contrast;
+		} else if (property == config->tv_flicker_reduction_property) {
+			prop = GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION;
+			val = connector->state->tv.flicker_reduction;
+		} else if (property == config->tv_overscan_property) {
+			prop = GUD_DRM_PROPERTY_TV_OVERSCAN;
+			val = connector->state->tv.overscan;
+		} else if (property == config->tv_saturation_property) {
+			prop = GUD_DRM_PROPERTY_TV_SATURATION;
+			val = connector->state->tv.saturation;
+		} else if (property == config->tv_hue_property) {
+			prop = GUD_DRM_PROPERTY_TV_HUE;
+			val = connector->state->tv.hue;
+		} else {
+			continue;
+		}
+
+		properties[gconn->num_properties].prop = cpu_to_le16(prop);
+		properties[gconn->num_properties++].val = cpu_to_le64(val);
+	}
+
+	if (!connector->index && gdg->backlight) {
+		struct backlight_properties *props = &gdg->backlight->props;
+
+		prop = GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS;
+		val = DIV64_U64_ROUND_UP(props->brightness * 100, props->max_brightness);
+		properties[gconn->num_properties].prop = cpu_to_le16(prop);
+		properties[gconn->num_properties++].val = cpu_to_le64(val);
+		gconn->backlight = gdg->backlight;
+	}
+unlock:
+	mutex_unlock(&drm->mode_config.mutex);
+
+	return ret;
+}
+
+static int gud_drm_gadget_get_connectors(struct gud_drm_gadget *gdg)
+{
+	struct gud_drm_gadget_connector *connectors = NULL;
+	struct drm_connector_list_iter conn_iter;
+	struct drm_device *drm = gdg->client.dev;
+	unsigned int connector_count = 0;
+	struct drm_connector *connector;
+	int ret = 0;
+
+	drm_connector_list_iter_begin(drm, &conn_iter);
+	drm_client_for_each_connector_iter(connector, &conn_iter) {
+		struct gud_drm_gadget_connector *tmp, *gconn;
+
+		tmp = krealloc(connectors, (connector_count + 1) * sizeof(*connectors),
+			       GFP_KERNEL | __GFP_ZERO);
+		if (!tmp) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		connectors = tmp;
+		drm_connector_get(connector);
+		gconn = &connectors[connector_count++];
+		gconn->connector = connector;
+		spin_lock_init(&gconn->lock);
+
+		ret = gud_drm_gadget_get_connector_properties(gdg, gconn);
+		if (ret)
+			break;
+	}
+	drm_connector_list_iter_end(&conn_iter);
+
+	gdg->connectors = connectors;
+	gdg->connector_count = connector_count;
+
+	return ret;
+}
+
+static void gud_drm_gadget_release(struct kref *kref)
+{
+	struct gud_drm_gadget *gdg = container_of(kref, struct gud_drm_gadget, refcount);
+
+	kfree(gdg);
+}
+
+static void gud_drm_gadget_put(struct gud_drm_gadget *gdg)
+{
+	kref_put(&gdg->refcount, gud_drm_gadget_release);
+}
+
+static void gud_drm_gadget_client_unregister(struct drm_client_dev *client)
+{
+	struct gud_drm_gadget *gdg = container_of(client, struct gud_drm_gadget, client);
+	int timeout = 10000 / 50;
+	unsigned int i;
+
+	/*
+	 * If usecnt doesn't drop to zero, try waiting for the gadget, but we
+	 * can't block the DRM driver forever. The worst case wait the gadget side
+	 * can hit are tens of seconds through the call to drm_client_modeset_commit().
+	 */
+	if (refcount_dec_and_test(&gdg->usecnt)) {
+		for (; timeout && refcount_read(&gdg->usecnt); timeout--)
+			msleep(50);
+	}
+
+	if (!timeout) {
+		pr_err("%s: Timeout waiting for gadget side, will leak memory\n", __func__);
+		return;
+	}
+
+	vfree(gdg->work_buf);
+	kfree(gdg->formats);
+	kfree(gdg->properties);
+
+	for (i = 0; i < gdg->connector_count; i++) {
+		struct gud_drm_gadget_connector *gconn = &gdg->connectors[i];
+
+		drm_connector_put(gconn->connector);
+		kfree(gconn->properties);
+		kfree(gconn->tv_mode_enum_names);
+		kfree(gconn->modes);
+		kfree(gconn->edid);
+	}
+	kfree(gdg->connectors);
+
+	gud_drm_gadget_delete_buffers(gdg);
+	drm_client_release(client);
+	gud_drm_gadget_put(gdg);
+}
+
+static int gud_drm_gadget_client_hotplug(struct drm_client_dev *client)
+{
+	struct gud_drm_gadget *gdg = container_of(client, struct gud_drm_gadget, client);
+
+	gud_drm_gadget_probe_connectors(gdg);
+
+	return 0;
+}
+
+static const struct drm_client_funcs gdg_client_funcs = {
+	.owner		= THIS_MODULE,
+	.unregister	= gud_drm_gadget_client_unregister,
+	.hotplug	= gud_drm_gadget_client_hotplug,
+};
+
+struct gud_drm_gadget *gud_drm_gadget_init(unsigned int minor_id, const char *backlight,
+					   size_t *max_buffer_size)
+{
+	struct gud_drm_gadget *gdg;
+	u8 max_cpp;
+	int ret;
+
+	gdg = kzalloc(sizeof(*gdg), GFP_KERNEL);
+	if (!gdg)
+		return ERR_PTR(-ENOMEM);
+
+	ret = drm_client_init_from_id(minor_id, &gdg->client, "gud-drm-gadget", &gdg_client_funcs);
+	if (ret) {
+		pr_err("Failed to aquire minor=%u\n", minor_id);
+		kfree(gdg);
+		return ERR_PTR(ret);
+	}
+
+	refcount_set(&gdg->usecnt, 1);
+	/* The DRM driver (through the client) and f_gud_drm need one ref each */
+	kref_init(&gdg->refcount);
+	kref_get(&gdg->refcount);
+
+	if (backlight) {
+		gdg->backlight = backlight_device_get_by_name(backlight);
+		if (!gdg->backlight) {
+			pr_err("Failed to find backlight: %s\n", backlight);
+			ret = -ENODEV;
+			goto error_release;
+		}
+	}
+
+	ret = gud_drm_gadget_get_formats(gdg, &max_cpp);
+	if (ret) {
+		pr_err("Failed to get formats\n");
+		goto error_release;
+	}
+
+	*max_buffer_size = gdg->client.dev->mode_config.max_width *
+			   gdg->client.dev->mode_config.max_height * max_cpp;
+	/* f_gud_drm will kmalloc a buffer of this size */
+	*max_buffer_size = min_t(size_t, *max_buffer_size, KMALLOC_MAX_SIZE);
+
+	gdg->max_buffer_size = *max_buffer_size;
+	gdg->work_buf = vmalloc(gdg->max_buffer_size);
+	if (!gdg->work_buf) {
+		ret = -ENOMEM;
+		goto error_release;
+	}
+
+	ret = gud_drm_gadget_get_properties(gdg);
+	if (ret) {
+		pr_err("Failed to get properties\n");
+		goto error_release;
+	}
+
+	ret = gud_drm_gadget_get_connectors(gdg);
+	if (ret) {
+		pr_err("Failed to get connectors\n");
+		goto error_release;
+	}
+
+	if (!drm_client_register(&gdg->client)) {
+		pr_err("DRM device is gone\n");
+		ret = -ENODEV;
+		goto error_release;
+	}
+
+	gud_drm_gadget_probe_connectors(gdg);
+
+	return gdg;
+
+error_release:
+	gud_drm_gadget_client_unregister(&gdg->client);
+	gud_drm_gadget_fini(gdg);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(gud_drm_gadget_init);
+
+void gud_drm_gadget_fini(struct gud_drm_gadget *gdg)
+{
+	backlight_put(gdg->backlight);
+	gud_drm_gadget_put(gdg);
+}
+EXPORT_SYMBOL(gud_drm_gadget_fini);
+
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");
diff --git a/include/drm/gud_drm.h b/include/drm/gud_drm.h
index 36d35bc7cff2..8686b59632af 100644
--- a/include/drm/gud_drm.h
+++ b/include/drm/gud_drm.h
@@ -361,4 +361,17 @@ static inline void gud_drm_to_display_mode(struct drm_display_mode *dst,
 	drm_mode_set_name(dst);
 }
 
+struct gud_drm_gadget;
+
+struct gud_drm_gadget *gud_drm_gadget_init(unsigned int minor_id, const char *backlight,
+					   size_t *max_buffer_size);
+void gud_drm_gadget_fini(struct gud_drm_gadget *gdg);
+int gud_drm_gadget_disable_pipe(struct gud_drm_gadget *gdg);
+int gud_drm_gadget_ctrl_get(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size);
+int gud_drm_gadget_ctrl_set(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size);
+int gud_drm_gadget_set_buffer(struct gud_drm_gadget *gdg, struct gud_drm_req_set_buffer *req);
+int gud_drm_gadget_write_buffer(struct gud_drm_gadget *gdg, const void *buf, size_t len);
+
 #endif
-- 
2.23.0

[PATCH v2 09/10] drm/gud: Add functionality for the USB gadget side

[Noralf Trønnes]

Since the USB gadget/device has to reach into the DRM internals, part of
the code is placed in the DRM subsystem as a separate module. All calls
into this module runs in process context and are serialized, except one
function that runs in interrupt context.

Since both the gadget side and the DRM side can disable the gadget,
special care has been taken to make that safe.

v2:
- Use drm_client_modeset_disable()

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/gud/Kconfig          |    6 +
 drivers/gpu/drm/gud/Makefile         |    1 +
 drivers/gpu/drm/gud/gud_drm_gadget.c | 1165 ++++++++++++++++++++++++++
 include/drm/gud_drm.h                |   13 +
 4 files changed, 1185 insertions(+)
 create mode 100644 drivers/gpu/drm/gud/gud_drm_gadget.c

diff --git a/drivers/gpu/drm/gud/Kconfig b/drivers/gpu/drm/gud/Kconfig
index 767f1c067ed9..9bbf39ae6191 100644
--- a/drivers/gpu/drm/gud/Kconfig
+++ b/drivers/gpu/drm/gud/Kconfig
@@ -12,3 +12,9 @@ config DRM_GUD
 	  adapters.
 
 	  If M is selected the module will be called gud_drm.
+
+config DRM_GUD_GADGET
+	tristate
+	depends on DRM
+	select LZ4_DECOMPRESS
+	select BACKLIGHT_CLASS_DEVICE
diff --git a/drivers/gpu/drm/gud/Makefile b/drivers/gpu/drm/gud/Makefile
index 73ed7ef3da94..fb5cfbd93d0f 100644
--- a/drivers/gpu/drm/gud/Makefile
+++ b/drivers/gpu/drm/gud/Makefile
@@ -2,3 +2,4 @@
 
 gud_drm-objs			:= gud_drm_drv.o gud_drm_pipe.o gud_drm_connector.o
 obj-$(CONFIG_DRM_GUD)		+= gud_drm.o
+obj-$(CONFIG_DRM_GUD_GADGET)	+= gud_drm_gadget.o
diff --git a/drivers/gpu/drm/gud/gud_drm_gadget.c b/drivers/gpu/drm/gud/gud_drm_gadget.c
new file mode 100644
index 000000000000..6bc438634ed3
--- /dev/null
+++ b/drivers/gpu/drm/gud/gud_drm_gadget.c
@@ -0,0 +1,1165 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2020 Noralf Trønnes
+ */
+
+#include <linux/backlight.h>
+#include <linux/delay.h>
+#include <linux/lz4.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+
+#include <drm/drm_client.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_mode_object.h>
+#include <drm/drm_plane.h>
+#include <drm/drm_rect.h>
+#include <drm/gud_drm.h>
+
+#include "gud_drm_internal.h"
+
+/*
+ * Concurrency:
+ * Calls into this module from f_gud_drm are serialized and run in process
+ * context except gud_drm_gadget_ctrl_get() which is run in interrupt context.
+ *
+ * Termination:
+ * A DRM client can not release itself, only the DRM driver which resources the
+ * client uses can do that.
+ * This means that there are 2 paths to stop the gadget function:
+ * - Unregistering the DRM driver (module unload)
+ * - Disabling the USB gadget (configfs unbind)
+ *
+ * A use counter protects the gadget should the client go away. A kref is used
+ * to control the release of the gud_drm_gadget structure shared by the 2 actors.
+ *
+ * Backlight:
+ * If there's a backlight device it's attached to the first connector.
+ */
+
+struct gud_drm_gadget_connector {
+	struct drm_connector *connector;
+
+	const struct gud_drm_property *properties;
+	unsigned int num_properties;
+	const char *tv_mode_enum_names;
+	unsigned int num_tv_mode_enum_names;
+	struct backlight_device *backlight;
+
+	spinlock_t lock; /* Protects the following members: */
+	enum drm_connector_status status;
+	unsigned int width_mm;
+	unsigned int height_mm;
+	struct gud_drm_display_mode *modes;
+	unsigned int num_modes;
+	void *edid;
+	size_t edid_len;
+	bool changed;
+};
+
+struct gud_drm_gadget {
+	struct kref refcount;
+	refcount_t usecnt;
+	struct drm_client_dev client;
+	struct backlight_device *backlight;
+
+	const u32 *formats;
+	unsigned int format_count;
+
+	const struct gud_drm_property *properties;
+	unsigned int num_properties;
+
+	struct gud_drm_gadget_connector *connectors;
+	unsigned int connector_count;
+
+	struct drm_rect set_buffer_rect;
+	u32 set_buffer_length;
+	u8 set_buffer_compression;
+	u32 set_buffer_compressed_length;
+
+	struct drm_client_buffer *buffer;
+	struct drm_client_buffer *buffer_check;
+	u8 brightness;
+	bool check_ok;
+
+	size_t max_buffer_size;
+	void *work_buf;
+};
+
+static int gud_drm_gadget_probe_connector(struct gud_drm_gadget_connector *gconn)
+{
+	struct drm_connector *connector = gconn->connector;
+	struct gud_drm_display_mode *modes = NULL;
+	struct drm_device *drm = connector->dev;
+	struct drm_display_mode *mode;
+	void *edid_data, *edid = NULL;
+	unsigned int num_modes = 0;
+	size_t edid_len = 0;
+	unsigned long flags;
+	unsigned int i = 0;
+	int ret = 0;
+
+	mutex_lock(&drm->mode_config.mutex);
+
+	connector->funcs->fill_modes(connector,
+				     drm->mode_config.max_width,
+				     drm->mode_config.max_height);
+
+	list_for_each_entry(mode, &connector->modes, head)
+		num_modes++;
+
+	if (!num_modes)
+		goto update;
+
+	modes = kmalloc_array(num_modes, sizeof(*modes), GFP_KERNEL);
+	if (!modes) {
+		ret = -ENOMEM;
+		num_modes = 0;
+		goto update;
+	}
+
+	list_for_each_entry(mode, &connector->modes, head)
+		gud_drm_from_display_mode(&modes[i++], mode);
+
+	if (!connector->edid_blob_ptr)
+		goto update;
+
+	edid_data = connector->edid_blob_ptr->data;
+	edid_len = connector->edid_blob_ptr->length;
+	if (!edid_data || !edid_len) {
+		edid_len = 0;
+		goto update;
+	}
+
+	edid = kmemdup(edid_data, edid_len, GFP_KERNEL);
+	if (!edid) {
+		ret = -ENOMEM;
+		edid_len = 0;
+	}
+
+update:
+	spin_lock_irqsave(&gconn->lock, flags);
+	if (gconn->status != connector->status || gconn->num_modes != num_modes ||
+	    gconn->edid_len != edid_len ||
+	    (gconn->modes && modes && memcmp(gconn->modes, modes, num_modes * sizeof(*modes))) ||
+	    (gconn->edid && edid && memcmp(gconn->edid, edid, edid_len)))
+		gconn->changed = true;
+	swap(gconn->modes, modes);
+	gconn->num_modes = num_modes;
+	swap(gconn->edid, edid);
+	gconn->edid_len = edid_len;
+	gconn->width_mm = connector->display_info.width_mm;
+	gconn->height_mm = connector->display_info.height_mm;
+	gconn->status = connector->status;
+	spin_unlock_irqrestore(&gconn->lock, flags);
+
+	mutex_unlock(&drm->mode_config.mutex);
+
+	kfree(edid);
+	kfree(modes);
+
+	return ret;
+}
+
+static void gud_drm_gadget_probe_connectors(struct gud_drm_gadget *gdg)
+{
+	unsigned int i;
+
+	for (i = 0; i < gdg->connector_count; i++)
+		gud_drm_gadget_probe_connector(&gdg->connectors[i]);
+}
+
+static bool gud_drm_gadget_check_buffer(struct gud_drm_gadget *gdg,
+					struct drm_client_buffer *buffer,
+					struct drm_display_mode *mode,
+					u32 format)
+{
+	struct drm_framebuffer *fb;
+
+	if (!buffer)
+		return false;
+
+	fb = buffer->fb;
+
+	return fb->format->format == format &&
+	       fb->width == mode->hdisplay && fb->height == mode->vdisplay;
+}
+
+static bool gud_drm_gadget_set_connector_property(struct drm_client_dev *client,
+						  struct drm_connector *connector,
+						  u16 prop, u64 val, int *ret)
+{
+	struct drm_mode_config *config = &connector->dev->mode_config;
+	struct drm_property *property;
+
+	switch (prop) {
+	case GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR:
+		property = config->tv_select_subconnector_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_LEFT_MARGIN:
+		property = config->tv_left_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_RIGHT_MARGIN:
+		property = config->tv_right_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_TOP_MARGIN:
+		property = config->tv_top_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN:
+		property = config->tv_bottom_margin_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_MODE:
+		property = config->tv_mode_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_BRIGHTNESS:
+		property = config->tv_brightness_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_CONTRAST:
+		property = config->tv_contrast_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION:
+		property = config->tv_flicker_reduction_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_OVERSCAN:
+		property = config->tv_overscan_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_SATURATION:
+		property = config->tv_saturation_property;
+		break;
+	case GUD_DRM_PROPERTY_TV_HUE:
+		property = config->tv_hue_property;
+		break;
+	default:
+		return false;
+	}
+
+	*ret = drm_client_modeset_set_property(client, &connector->base, property, val);
+
+	return true;
+}
+
+static int gud_drm_gadget_check(struct gud_drm_gadget *gdg, struct gud_drm_req_set_state *req,
+				size_t size)
+{
+	struct drm_client_dev *client = &gdg->client;
+	u32 format = le32_to_cpu(req->format);
+	struct drm_client_buffer *buffer;
+	struct drm_connector *connector;
+	struct drm_display_mode mode;
+	unsigned int i;
+	void *vaddr;
+	int ret;
+
+	if (size < sizeof(struct gud_drm_req_set_state))
+		return -EINVAL;
+
+	if (size != struct_size(req, properties, req->num_properties))
+		return -EINVAL;
+
+	memset(&mode, 0, sizeof(mode));
+	gud_drm_to_display_mode(&mode, &req->mode);
+
+	gdg->check_ok = false;
+
+	if (!mode.hdisplay || !format)
+		return -EINVAL;
+
+	if (req->connector >= gdg->connector_count)
+		return -EINVAL;
+
+	connector = gdg->connectors[req->connector].connector;
+
+	if (gdg->buffer_check) {
+		drm_client_framebuffer_delete(gdg->buffer_check);
+		gdg->buffer_check = NULL;
+	}
+
+	if (!gud_drm_gadget_check_buffer(gdg, gdg->buffer, &mode, format)) {
+		buffer = drm_client_framebuffer_create(client, mode.hdisplay, mode.vdisplay,
+						       format);
+		if (IS_ERR(buffer))
+			return PTR_ERR(buffer);
+
+		vaddr = drm_client_buffer_vmap(buffer);
+		if (IS_ERR(vaddr)) {
+			drm_client_framebuffer_delete(buffer);
+			return PTR_ERR(vaddr);
+		}
+
+		gdg->buffer_check = buffer;
+	} else {
+		buffer = gdg->buffer;
+	}
+
+	ret = drm_client_modeset_set(client, connector, &mode, buffer->fb);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < req->num_properties; i++) {
+		u16 prop = le16_to_cpu(req->properties[i].prop);
+		u64 val = le64_to_cpu(req->properties[i].val);
+
+		if (gud_drm_gadget_set_connector_property(client, connector, prop, val, &ret)) {
+			if (ret)
+				return ret;
+			continue;
+		}
+
+		switch (prop) {
+		case GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS:
+			if (val > 100)
+				return -EINVAL;
+			gdg->brightness = val;
+			break;
+		case GUD_DRM_PROPERTY_ROTATION:
+			ret = drm_client_modeset_set_rotation(client, val);
+			break;
+		default:
+			pr_err("%s: Unknown property: %u\n", __func__, prop);
+			continue;
+		}
+
+		if (ret)
+			return ret;
+	}
+
+	ret = drm_client_modeset_check(&gdg->client);
+	if (ret)
+		return ret;
+
+	gdg->check_ok = true;
+
+	return 0;
+}
+
+static int gud_drm_gadget_commit(struct gud_drm_gadget *gdg)
+{
+	int ret;
+
+	if (!gdg->check_ok)
+		return -EINVAL;
+
+	if (gdg->backlight) {
+		int val, max_brightness = gdg->backlight->props.max_brightness;
+
+		val = DIV64_U64_ROUND_UP(gdg->brightness * max_brightness, 100);
+		ret = backlight_device_set_brightness(gdg->backlight, val);
+		if (ret)
+			return ret;
+	}
+
+	ret = drm_client_modeset_commit(&gdg->client);
+	if (ret)
+		return ret;
+
+	if (gdg->buffer_check) {
+		drm_client_framebuffer_delete(gdg->buffer);
+		gdg->buffer = gdg->buffer_check;
+		gdg->buffer_check = NULL;
+	}
+
+	return 0;
+}
+
+static size_t gud_drm_gadget_write_buffer_memcpy(struct drm_client_buffer *buffer,
+						 const void *src, size_t len,
+						 struct drm_rect *rect)
+{
+	unsigned int cpp = buffer->fb->format->cpp[0];
+	size_t dst_pitch = buffer->fb->pitches[0];
+	size_t src_pitch = drm_rect_width(rect) * cpp;
+	unsigned int y;
+	void *dst;
+
+	/* Get the address, it's already mapped */
+	dst = drm_client_buffer_vmap(buffer);
+	dst += rect->y1 * dst_pitch;
+	dst += rect->x1 * cpp;
+
+	for (y = 0; y < drm_rect_height(rect) && len; y++) {
+		src_pitch = min(src_pitch, len);
+		memcpy(dst, src, src_pitch);
+		src += src_pitch;
+		dst += dst_pitch;
+		len -= src_pitch;
+	}
+
+	return len;
+}
+
+static bool gud_drm_gadget_check_rect(struct drm_client_buffer *buffer, struct drm_rect *rect)
+{
+	return buffer->fb && rect->x1 < rect->x2 && rect->y1 < rect->y2 &&
+	       rect->x2 <= buffer->fb->width && rect->y2 <= buffer->fb->height;
+}
+
+int gud_drm_gadget_write_buffer(struct gud_drm_gadget *gdg, const void *buf, size_t len)
+{
+	struct drm_client_buffer *buffer = gdg->buffer ? gdg->buffer : gdg->buffer_check;
+	struct drm_rect *rect = &gdg->set_buffer_rect;
+	u8 compression = gdg->set_buffer_compression;
+	struct drm_framebuffer *fb;
+	size_t remain;
+	int ret;
+
+	pr_debug("%s: len=%zu compression=0x%x\n", __func__, len, compression);
+
+	if (WARN_ON_ONCE(!buffer))
+		return -ENOMEM;
+
+	if (!gud_drm_gadget_check_rect(buffer, rect)) {
+		pr_err("%s: Rectangle doesn't fit\n", __func__);
+		return -EINVAL;
+	}
+
+	fb = buffer->fb;
+
+	if (compression & GUD_DRM_COMPRESSION_LZ4) {
+		if (len != gdg->set_buffer_compressed_length) {
+			pr_err("%s: Buffer compressed len differs: %zu != %zu\n",
+			       __func__, len, gdg->set_buffer_compressed_length);
+			return -EINVAL;
+		}
+
+		ret = LZ4_decompress_safe(buf, gdg->work_buf, len, gdg->max_buffer_size);
+		if (ret < 0) {
+			pr_err("%s: Failed to decompress buffer\n", __func__);
+			return -EIO;
+		}
+
+		buf = gdg->work_buf;
+		len = ret;
+	}
+
+	if (len != gdg->set_buffer_length) {
+		pr_err("%s: Buffer len differs: %zu != %zu\n",
+		       __func__, len, gdg->set_buffer_length);
+		return -EINVAL;
+	}
+
+	if (len > (drm_rect_width(rect) * drm_rect_height(rect) * fb->format->cpp[0])) {
+		pr_err("%s: Buffer is too big for rectangle\n", __func__);
+		return -EINVAL;
+	}
+
+	remain = gud_drm_gadget_write_buffer_memcpy(buffer, buf, len, rect);
+	if (remain) {
+		pr_err("%s: Failed to write buffer: remain=%zu\n", __func__, remain);
+		return -EIO;
+	}
+
+	return drm_client_framebuffer_flush(buffer, rect);
+}
+EXPORT_SYMBOL(gud_drm_gadget_write_buffer);
+
+int gud_drm_gadget_set_buffer(struct gud_drm_gadget *gdg, struct gud_drm_req_set_buffer *req)
+{
+	u32 compressed_length = le32_to_cpu(req->compressed_length);
+	u32 length = le32_to_cpu(req->length);
+	struct drm_client_buffer *buffer;
+	struct drm_rect rect;
+	int ret = 0;
+
+	if (!refcount_inc_not_zero(&gdg->usecnt))
+		return -ENODEV;
+
+	buffer = gdg->buffer ? gdg->buffer : gdg->buffer_check;
+	if (!buffer) {
+		ret = -ENOENT;
+		goto out;
+	}
+
+	drm_rect_init(&rect, le32_to_cpu(req->x), le32_to_cpu(req->y),
+		      le32_to_cpu(req->width), le32_to_cpu(req->height));
+
+	pr_debug("%s: " DRM_RECT_FMT "\n", __func__, DRM_RECT_ARG(&rect));
+
+	if (!gud_drm_gadget_check_rect(buffer, &rect)) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (req->compression & ~GUD_DRM_COMPRESSION_LZ4) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	gdg->set_buffer_rect = rect;
+	gdg->set_buffer_length = length;
+
+	if (req->compression) {
+		if (!compressed_length) {
+			ret = -EINVAL;
+			goto out;
+		}
+		gdg->set_buffer_compression = req->compression;
+		gdg->set_buffer_compressed_length = compressed_length;
+		length = compressed_length;
+	} else {
+		gdg->set_buffer_compression = 0;
+		gdg->set_buffer_compressed_length = 0;
+	}
+out:
+	refcount_dec(&gdg->usecnt);
+
+	return ret ? ret : length;
+}
+EXPORT_SYMBOL(gud_drm_gadget_set_buffer);
+
+static void gud_drm_gadget_delete_buffers(struct gud_drm_gadget *gdg)
+{
+	drm_client_framebuffer_delete(gdg->buffer_check);
+	drm_client_framebuffer_delete(gdg->buffer);
+	gdg->buffer_check = NULL;
+	gdg->buffer = NULL;
+}
+
+int gud_drm_gadget_disable_pipe(struct gud_drm_gadget *gdg)
+{
+	int ret;
+
+	ret = drm_client_modeset_disable(&gdg->client);
+	gud_drm_gadget_delete_buffers(gdg);
+
+	return ret;
+}
+EXPORT_SYMBOL(gud_drm_gadget_disable_pipe);
+
+static int gud_drm_gadget_ctrl_get_display_descriptor(struct gud_drm_gadget *gdg, u16 value,
+						      void *data, size_t size)
+{
+	struct drm_device *drm = gdg->client.dev;
+	struct gud_drm_display_descriptor desc;
+	u8 type = value >> 8;
+	u8 index = value & 0xff;
+
+	if (type != GUD_DRM_USB_DT_DISPLAY || index)
+		return -EINVAL;
+
+	desc.bLength = sizeof(desc);
+	desc.bDescriptorType = GUD_DRM_USB_DT_DISPLAY;
+
+	desc.bVersion = 1;
+	desc.bMaxBufferSizeOrder = ilog2(gdg->max_buffer_size);
+	desc.bmFlags = 0;
+	desc.bCompression = GUD_DRM_COMPRESSION_LZ4;
+
+	desc.dwMinWidth = cpu_to_le32(drm->mode_config.min_width);
+	desc.dwMaxWidth = cpu_to_le32(drm->mode_config.max_width);
+	desc.dwMinHeight = cpu_to_le32(drm->mode_config.min_height);
+	desc.dwMaxHeight = cpu_to_le32(drm->mode_config.max_height);
+	desc.bNumFormats = gdg->format_count;
+	desc.bNumProperties = gdg->num_properties;
+	desc.bNumConnectors = gdg->connector_count;
+
+	size = min(size, sizeof(desc));
+	memcpy(data, &desc, size);
+
+	return size;
+}
+
+static void gud_drm_gadget_ctrl_get_formats(struct gud_drm_gadget *gdg, __le32 *formats)
+{
+	unsigned int i;
+
+	for (i = 0; i < gdg->format_count; i++)
+		formats[i] = cpu_to_le32(gdg->formats[i]);
+}
+
+static int gud_drm_gadget_ctrl_get_connector(struct gud_drm_gadget *gdg, unsigned int index,
+					     struct gud_drm_req_get_connector *desc)
+{
+	struct gud_drm_gadget_connector *gconn;
+
+	if (index >= gdg->connector_count)
+		return -EINVAL;
+
+	memset(desc, 0, sizeof(*desc));
+
+	gconn = &gdg->connectors[index];
+
+	desc->connector_type = gconn->connector->connector_type;
+	desc->flags = cpu_to_le32(GUD_DRM_CONNECTOR_FLAGS_POLL);
+	desc->num_properties = gconn->num_properties;
+
+	return 0;
+}
+
+static struct gud_drm_gadget_connector *
+gud_drm_gadget_get_gconn(struct gud_drm_gadget *gdg, unsigned int index)
+{
+	if (index >= gdg->connector_count)
+		return NULL;
+
+	return &gdg->connectors[index];
+}
+
+static int gud_drm_gadget_ctrl_get_connector_status(struct gud_drm_gadget *gdg, unsigned int index,
+						    struct gud_drm_req_get_connector_status *status)
+{
+	struct gud_drm_gadget_connector *gconn;
+	unsigned long flags;
+
+	gconn = gud_drm_gadget_get_gconn(gdg, index);
+	if (!gconn)
+		return -ENOENT;
+
+	memset(status, 0, sizeof(*status));
+
+	spin_lock_irqsave(&gconn->lock, flags);
+	status->status = gconn->status;
+	if (gconn->changed) {
+		status->status |= GUD_DRM_CONNECTOR_STATUS_CHANGED;
+		gconn->changed = false;
+	}
+	if (gconn->num_modes)
+		status->num_modes = cpu_to_le16(gconn->num_modes);
+	if (gconn->edid_len)
+		status->edid_len = cpu_to_le16(gconn->edid_len);
+	spin_unlock_irqrestore(&gconn->lock, flags);
+
+	return 0;
+}
+
+/* This runs in interrupt context */
+int gud_drm_gadget_ctrl_get(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size)
+{
+	struct gud_drm_gadget_connector *gconn;
+	unsigned long flags;
+	int ret = -EINVAL;
+
+	pr_debug("%s: request=0x%x index=%u size=%zu\n", __func__, request, index, size);
+
+	if (!refcount_inc_not_zero(&gdg->usecnt))
+		return -ENODEV;
+
+	if (!size)
+		goto out;
+
+	switch (request) {
+	case USB_REQ_GET_DESCRIPTOR:
+		ret = gud_drm_gadget_ctrl_get_display_descriptor(gdg, index, data, size);
+		break;
+	case GUD_DRM_USB_REQ_GET_FORMATS:
+		if (!index && size == gdg->format_count * sizeof(u32)) {
+			gud_drm_gadget_ctrl_get_formats(gdg, data);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_PROPERTIES:
+		if (!index && size == gdg->num_properties * sizeof(*gdg->properties)) {
+			memcpy(data, gdg->properties, size);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR:
+		if (size == sizeof(struct gud_drm_req_get_connector))
+			ret = gud_drm_gadget_ctrl_get_connector(gdg, index, data);
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_PROPERTIES:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		if (gconn && size == gconn->num_properties * sizeof(*gconn->properties)) {
+			memcpy(data, gconn->properties, size);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_TV_MODE_VALUES:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		if (gconn && size == gconn->num_tv_mode_enum_names * DRM_PROP_NAME_LEN) {
+			memcpy(data, gconn->tv_mode_enum_names, size);
+			ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_STATUS:
+		if (size == sizeof(struct gud_drm_req_get_connector_status))
+			ret = gud_drm_gadget_ctrl_get_connector_status(gdg, index, data);
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_MODES:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		spin_lock_irqsave(&gconn->lock, flags);
+		if (gconn && size == gconn->num_modes * sizeof(*gconn->modes)) {
+			memcpy(data, gconn->modes, size);
+			ret = 0;
+		}
+		spin_unlock_irqrestore(&gconn->lock, flags);
+		break;
+	case GUD_DRM_USB_REQ_GET_CONNECTOR_EDID:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		spin_lock_irqsave(&gconn->lock, flags);
+		if (gconn && size == gconn->edid_len) {
+			memcpy(data, gconn->edid, size);
+			ret = 0;
+		}
+		spin_unlock_irqrestore(&gconn->lock, flags);
+		break;
+	}
+out:
+	refcount_dec(&gdg->usecnt);
+
+	return !ret ? size : ret;
+}
+EXPORT_SYMBOL(gud_drm_gadget_ctrl_get);
+
+int gud_drm_gadget_ctrl_set(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size)
+{
+	struct gud_drm_gadget_connector *gconn;
+	int dpms, ret = -EINVAL;
+
+	pr_debug("%s: request=0x%x index=%u size=%zu\n", __func__, request, index, size);
+
+	if (!refcount_inc_not_zero(&gdg->usecnt))
+		return -ENODEV;
+
+	switch (request) {
+	case GUD_DRM_USB_REQ_SET_CONNECTOR_FORCE_DETECT:
+		gconn = gud_drm_gadget_get_gconn(gdg, index);
+		if (gconn)
+			ret = gud_drm_gadget_probe_connector(gconn);
+		break;
+	case GUD_DRM_USB_REQ_SET_STATE_CHECK:
+		ret = gud_drm_gadget_check(gdg, data, size);
+		break;
+	case GUD_DRM_USB_REQ_SET_STATE_COMMIT:
+		if (!size)
+			ret = gud_drm_gadget_commit(gdg);
+		break;
+	case GUD_DRM_USB_REQ_SET_CONTROLLER_ENABLE:
+		if (size == sizeof(u8)) {
+			if (*(u8 *)data == 0)
+				ret = gud_drm_gadget_disable_pipe(gdg);
+			else
+				ret = 0;
+		}
+		break;
+	case GUD_DRM_USB_REQ_SET_DISPLAY_ENABLE:
+		if (size == sizeof(u8)) {
+			dpms = *(u8 *)data ? DRM_MODE_DPMS_ON : DRM_MODE_DPMS_OFF;
+			ret = drm_client_modeset_dpms(&gdg->client, dpms);
+		}
+		break;
+	}
+
+	refcount_dec(&gdg->usecnt);
+
+	return ret;
+}
+EXPORT_SYMBOL(gud_drm_gadget_ctrl_set);
+
+static int gud_drm_gadget_get_formats(struct gud_drm_gadget *gdg, u8 *max_cpp)
+{
+	struct drm_device *drm = gdg->client.dev;
+	struct drm_plane *plane;
+	unsigned int i;
+	u32 *formats;
+	int ret;
+
+	*max_cpp = 0;
+
+	drm_for_each_plane(plane, drm) {
+		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
+			break;
+	}
+
+	formats = kcalloc(plane->format_count, sizeof(u32), GFP_KERNEL);
+	if (!formats)
+		return -ENOMEM;
+
+	for (i = 0; i < plane->format_count; i++) {
+		const struct drm_format_info *fmt;
+
+		fmt = drm_format_info(plane->format_types[i]);
+		if (fmt->num_planes != 1)
+			continue;
+
+		/*
+		 * Supporting 24-bit bpp would add complexity so don't bother.
+		 * It's hardly used and compression removes much of the gain.
+		 */
+		if (fmt->cpp[0] == 3)
+			continue;
+
+		if (*max_cpp < fmt->cpp[0])
+			*max_cpp = fmt->cpp[0];
+
+		formats[gdg->format_count++] = plane->format_types[i];
+	}
+
+	if (!gdg->format_count) {
+		ret = -ENOENT;
+		goto err_free;
+	}
+
+	gdg->formats = formats;
+
+	return 0;
+
+err_free:
+	kfree(formats);
+
+	return ret;
+}
+
+static int gud_drm_gadget_get_rotation_property(struct drm_device *drm, u16 *prop, u64 *val)
+{
+	struct drm_property_enum *prop_enum;
+	struct drm_plane *plane;
+	unsigned int num_props = 0;
+	u16 bitmask = 0;
+
+	drm_for_each_plane(plane, drm) {
+		if (plane->type == DRM_PLANE_TYPE_PRIMARY)
+			break;
+	}
+
+	if (!plane->rotation_property)
+		return 0;
+
+	list_for_each_entry(prop_enum, &plane->rotation_property->enum_list, head) {
+		num_props++;
+		bitmask |= BIT(prop_enum->value);
+	}
+
+	*prop = GUD_DRM_PROPERTY_ROTATION;
+	*val = bitmask;
+
+	return 1;
+}
+
+static int gud_drm_gadget_get_properties(struct gud_drm_gadget *gdg)
+{
+	struct gud_drm_property *properties;
+	u16 prop;
+	u64 val;
+	int ret;
+
+	ret = gud_drm_gadget_get_rotation_property(gdg->client.dev, &prop, &val);
+	if (ret <= 0)
+		return ret;
+
+	properties = kcalloc(1, sizeof(*properties), GFP_KERNEL);
+	if (!properties)
+		return -ENOMEM;
+
+	gdg->properties = properties;
+	gdg->num_properties++;
+
+	properties[0].prop = cpu_to_le16(prop);
+	properties[0].val = cpu_to_le64(val);
+
+	return 0;
+}
+
+static int gud_drm_gadget_get_connector_properties(struct gud_drm_gadget *gdg,
+						   struct gud_drm_gadget_connector *gconn)
+{
+	struct drm_device *drm = gdg->client.dev;
+	struct drm_mode_config *config = &drm->mode_config;
+	struct drm_connector *connector = gconn->connector;
+	struct drm_object_properties *conn_props = connector->base.properties;
+	struct gud_drm_property *properties;
+	unsigned int i, ret = 0;
+	u16 prop;
+	u64 val;
+
+	mutex_lock(&drm->mode_config.mutex);
+
+	if (!conn_props->count)
+		goto unlock;
+
+	/* Add room for possible backlight */
+	properties = kcalloc(conn_props->count + 1, sizeof(*properties), GFP_KERNEL);
+	if (!properties) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	gconn->properties = properties;
+
+	for (i = 0; i < conn_props->count; i++) {
+		struct drm_property *property = conn_props->properties[i];
+
+		if (property == config->tv_select_subconnector_property) {
+			prop = GUD_DRM_PROPERTY_TV_SELECT_SUBCONNECTOR;
+			val = connector->state->tv.subconnector;
+		} else if (property == config->tv_left_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_LEFT_MARGIN;
+			val = connector->state->tv.margins.left;
+		} else if (property == config->tv_right_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_RIGHT_MARGIN;
+			val = connector->state->tv.margins.right;
+		} else if (property == config->tv_top_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_TOP_MARGIN;
+			val = connector->state->tv.margins.top;
+		} else if (property == config->tv_bottom_margin_property) {
+			prop = GUD_DRM_PROPERTY_TV_BOTTOM_MARGIN;
+			val = connector->state->tv.margins.bottom;
+		} else if (property == config->tv_mode_property) {
+			struct drm_property_enum *prop_enum;
+			char *buf;
+
+			list_for_each_entry(prop_enum, &property->enum_list, head)
+				gconn->num_tv_mode_enum_names++;
+
+			if (WARN_ON(!gconn->num_tv_mode_enum_names)) {
+				ret = -EINVAL;
+				goto unlock;
+			}
+
+			buf = kcalloc(gconn->num_tv_mode_enum_names, DRM_PROP_NAME_LEN, GFP_KERNEL);
+			if (!buf) {
+				ret = -ENOMEM;
+				goto unlock;
+			}
+
+			gconn->tv_mode_enum_names = buf;
+
+			list_for_each_entry(prop_enum, &property->enum_list, head) {
+				strncpy(buf, prop_enum->name, DRM_PROP_NAME_LEN);
+				buf += DRM_PROP_NAME_LEN;
+			}
+
+			prop = GUD_DRM_PROPERTY_TV_MODE;
+			val = connector->state->tv.mode;
+			val |= gconn->num_tv_mode_enum_names << GUD_DRM_USB_CONNECTOR_TV_MODE_NUM_SHIFT;
+		} else if (property == config->tv_brightness_property) {
+			prop = GUD_DRM_PROPERTY_TV_BRIGHTNESS;
+			val = connector->state->tv.brightness;
+		} else if (property == config->tv_contrast_property) {
+			prop = GUD_DRM_PROPERTY_TV_CONTRAST;
+			val = connector->state->tv.contrast;
+		} else if (property == config->tv_flicker_reduction_property) {
+			prop = GUD_DRM_PROPERTY_TV_FLICKER_REDUCTION;
+			val = connector->state->tv.flicker_reduction;
+		} else if (property == config->tv_overscan_property) {
+			prop = GUD_DRM_PROPERTY_TV_OVERSCAN;
+			val = connector->state->tv.overscan;
+		} else if (property == config->tv_saturation_property) {
+			prop = GUD_DRM_PROPERTY_TV_SATURATION;
+			val = connector->state->tv.saturation;
+		} else if (property == config->tv_hue_property) {
+			prop = GUD_DRM_PROPERTY_TV_HUE;
+			val = connector->state->tv.hue;
+		} else {
+			continue;
+		}
+
+		properties[gconn->num_properties].prop = cpu_to_le16(prop);
+		properties[gconn->num_properties++].val = cpu_to_le64(val);
+	}
+
+	if (!connector->index && gdg->backlight) {
+		struct backlight_properties *props = &gdg->backlight->props;
+
+		prop = GUD_DRM_PROPERTY_BACKLIGHT_BRIGHTNESS;
+		val = DIV64_U64_ROUND_UP(props->brightness * 100, props->max_brightness);
+		properties[gconn->num_properties].prop = cpu_to_le16(prop);
+		properties[gconn->num_properties++].val = cpu_to_le64(val);
+		gconn->backlight = gdg->backlight;
+	}
+unlock:
+	mutex_unlock(&drm->mode_config.mutex);
+
+	return ret;
+}
+
+static int gud_drm_gadget_get_connectors(struct gud_drm_gadget *gdg)
+{
+	struct gud_drm_gadget_connector *connectors = NULL;
+	struct drm_connector_list_iter conn_iter;
+	struct drm_device *drm = gdg->client.dev;
+	unsigned int connector_count = 0;
+	struct drm_connector *connector;
+	int ret = 0;
+
+	drm_connector_list_iter_begin(drm, &conn_iter);
+	drm_client_for_each_connector_iter(connector, &conn_iter) {
+		struct gud_drm_gadget_connector *tmp, *gconn;
+
+		tmp = krealloc(connectors, (connector_count + 1) * sizeof(*connectors),
+			       GFP_KERNEL | __GFP_ZERO);
+		if (!tmp) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		connectors = tmp;
+		drm_connector_get(connector);
+		gconn = &connectors[connector_count++];
+		gconn->connector = connector;
+		spin_lock_init(&gconn->lock);
+
+		ret = gud_drm_gadget_get_connector_properties(gdg, gconn);
+		if (ret)
+			break;
+	}
+	drm_connector_list_iter_end(&conn_iter);
+
+	gdg->connectors = connectors;
+	gdg->connector_count = connector_count;
+
+	return ret;
+}
+
+static void gud_drm_gadget_release(struct kref *kref)
+{
+	struct gud_drm_gadget *gdg = container_of(kref, struct gud_drm_gadget, refcount);
+
+	kfree(gdg);
+}
+
+static void gud_drm_gadget_put(struct gud_drm_gadget *gdg)
+{
+	kref_put(&gdg->refcount, gud_drm_gadget_release);
+}
+
+static void gud_drm_gadget_client_unregister(struct drm_client_dev *client)
+{
+	struct gud_drm_gadget *gdg = container_of(client, struct gud_drm_gadget, client);
+	int timeout = 10000 / 50;
+	unsigned int i;
+
+	/*
+	 * If usecnt doesn't drop to zero, try waiting for the gadget, but we
+	 * can't block the DRM driver forever. The worst case wait the gadget side
+	 * can hit are tens of seconds through the call to drm_client_modeset_commit().
+	 */
+	if (refcount_dec_and_test(&gdg->usecnt)) {
+		for (; timeout && refcount_read(&gdg->usecnt); timeout--)
+			msleep(50);
+	}
+
+	if (!timeout) {
+		pr_err("%s: Timeout waiting for gadget side, will leak memory\n", __func__);
+		return;
+	}
+
+	vfree(gdg->work_buf);
+	kfree(gdg->formats);
+	kfree(gdg->properties);
+
+	for (i = 0; i < gdg->connector_count; i++) {
+		struct gud_drm_gadget_connector *gconn = &gdg->connectors[i];
+
+		drm_connector_put(gconn->connector);
+		kfree(gconn->properties);
+		kfree(gconn->tv_mode_enum_names);
+		kfree(gconn->modes);
+		kfree(gconn->edid);
+	}
+	kfree(gdg->connectors);
+
+	gud_drm_gadget_delete_buffers(gdg);
+	drm_client_release(client);
+	gud_drm_gadget_put(gdg);
+}
+
+static int gud_drm_gadget_client_hotplug(struct drm_client_dev *client)
+{
+	struct gud_drm_gadget *gdg = container_of(client, struct gud_drm_gadget, client);
+
+	gud_drm_gadget_probe_connectors(gdg);
+
+	return 0;
+}
+
+static const struct drm_client_funcs gdg_client_funcs = {
+	.owner		= THIS_MODULE,
+	.unregister	= gud_drm_gadget_client_unregister,
+	.hotplug	= gud_drm_gadget_client_hotplug,
+};
+
+struct gud_drm_gadget *gud_drm_gadget_init(unsigned int minor_id, const char *backlight,
+					   size_t *max_buffer_size)
+{
+	struct gud_drm_gadget *gdg;
+	u8 max_cpp;
+	int ret;
+
+	gdg = kzalloc(sizeof(*gdg), GFP_KERNEL);
+	if (!gdg)
+		return ERR_PTR(-ENOMEM);
+
+	ret = drm_client_init_from_id(minor_id, &gdg->client, "gud-drm-gadget", &gdg_client_funcs);
+	if (ret) {
+		pr_err("Failed to aquire minor=%u\n", minor_id);
+		kfree(gdg);
+		return ERR_PTR(ret);
+	}
+
+	refcount_set(&gdg->usecnt, 1);
+	/* The DRM driver (through the client) and f_gud_drm need one ref each */
+	kref_init(&gdg->refcount);
+	kref_get(&gdg->refcount);
+
+	if (backlight) {
+		gdg->backlight = backlight_device_get_by_name(backlight);
+		if (!gdg->backlight) {
+			pr_err("Failed to find backlight: %s\n", backlight);
+			ret = -ENODEV;
+			goto error_release;
+		}
+	}
+
+	ret = gud_drm_gadget_get_formats(gdg, &max_cpp);
+	if (ret) {
+		pr_err("Failed to get formats\n");
+		goto error_release;
+	}
+
+	*max_buffer_size = gdg->client.dev->mode_config.max_width *
+			   gdg->client.dev->mode_config.max_height * max_cpp;
+	/* f_gud_drm will kmalloc a buffer of this size */
+	*max_buffer_size = min_t(size_t, *max_buffer_size, KMALLOC_MAX_SIZE);
+
+	gdg->max_buffer_size = *max_buffer_size;
+	gdg->work_buf = vmalloc(gdg->max_buffer_size);
+	if (!gdg->work_buf) {
+		ret = -ENOMEM;
+		goto error_release;
+	}
+
+	ret = gud_drm_gadget_get_properties(gdg);
+	if (ret) {
+		pr_err("Failed to get properties\n");
+		goto error_release;
+	}
+
+	ret = gud_drm_gadget_get_connectors(gdg);
+	if (ret) {
+		pr_err("Failed to get connectors\n");
+		goto error_release;
+	}
+
+	if (!drm_client_register(&gdg->client)) {
+		pr_err("DRM device is gone\n");
+		ret = -ENODEV;
+		goto error_release;
+	}
+
+	gud_drm_gadget_probe_connectors(gdg);
+
+	return gdg;
+
+error_release:
+	gud_drm_gadget_client_unregister(&gdg->client);
+	gud_drm_gadget_fini(gdg);
+
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(gud_drm_gadget_init);
+
+void gud_drm_gadget_fini(struct gud_drm_gadget *gdg)
+{
+	backlight_put(gdg->backlight);
+	gud_drm_gadget_put(gdg);
+}
+EXPORT_SYMBOL(gud_drm_gadget_fini);
+
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");
diff --git a/include/drm/gud_drm.h b/include/drm/gud_drm.h
index 36d35bc7cff2..8686b59632af 100644
--- a/include/drm/gud_drm.h
+++ b/include/drm/gud_drm.h
@@ -361,4 +361,17 @@ static inline void gud_drm_to_display_mode(struct drm_display_mode *dst,
 	drm_mode_set_name(dst);
 }
 
+struct gud_drm_gadget;
+
+struct gud_drm_gadget *gud_drm_gadget_init(unsigned int minor_id, const char *backlight,
+					   size_t *max_buffer_size);
+void gud_drm_gadget_fini(struct gud_drm_gadget *gdg);
+int gud_drm_gadget_disable_pipe(struct gud_drm_gadget *gdg);
+int gud_drm_gadget_ctrl_get(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size);
+int gud_drm_gadget_ctrl_set(struct gud_drm_gadget *gdg, u8 request,
+			    u16 index, void *data, size_t size);
+int gud_drm_gadget_set_buffer(struct gud_drm_gadget *gdg, struct gud_drm_req_set_buffer *req);
+int gud_drm_gadget_write_buffer(struct gud_drm_gadget *gdg, const void *buf, size_t len);
+
 #endif
-- 
2.23.0

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

[PATCH v2 10/10] usb: gadget: function: Add Generic USB Display support

[Noralf Trønnes]

This adds the gadget side support for the Generic USB Display. It presents
a DRM display device as a USB Display configured through configfs.

The display is implemented as a vendor type USB interface with one bulk
out endpoint. The protocol is implemented using control requests.
lz4 compressed framebuffer data/pixels are sent over the bulk endpoint.

The DRM part of the gadget is placed in the DRM subsystem since it reaches
into the DRM internals.

Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 .../ABI/testing/configfs-usb-gadget-gud_drm   |  10 +
 MAINTAINERS                                   |   2 +
 drivers/usb/gadget/Kconfig                    |  12 +
 drivers/usb/gadget/function/Makefile          |   2 +
 drivers/usb/gadget/function/f_gud_drm.c       | 678 ++++++++++++++++++
 5 files changed, 704 insertions(+)
 create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-gud_drm
 create mode 100644 drivers/usb/gadget/function/f_gud_drm.c

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-gud_drm b/Documentation/ABI/testing/configfs-usb-gadget-gud_drm
new file mode 100644
index 000000000000..4f865e7fea58
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-gud_drm
@@ -0,0 +1,10 @@
+What:		/config/usb-gadget/gadget/functions/gud_drm.name
+Date:		May 2020
+KernelVersion:	5.9
+Description:
+		The attributes:
+
+		drm_dev - DRM device number
+		backlight_dev - Backlight device name (optional)
+				The backlight brightness scale should be
+				perceptual not linear.
diff --git a/MAINTAINERS b/MAINTAINERS
index 7494a21ea41e..4bc5dc7296b8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5296,7 +5296,9 @@ M:	Noralf Trønnes <noralf@tronnes.org>
 S:	Maintained
 W:	https://github.com/notro/gud/wiki
 T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	Documentation/ABI/testing/configfs-usb-gadget-gud_drm
 F:	drivers/gpu/drm/gud/
+F:	drivers/usb/gadget/function/f_gud_drm.c
 F:	include/drm/gud_drm.h
 
 DRM DRIVER FOR GRAIN MEDIA GM12U320 PROJECTORS
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index c6db0a0a340c..8d90add495b6 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -216,6 +216,9 @@ config USB_F_PRINTER
 config USB_F_TCM
 	tristate
 
+config USB_F_GUD_DRM
+	tristate
+
 # this first set of drivers all depend on bulk-capable hardware.
 
 config USB_CONFIGFS
@@ -483,6 +486,15 @@ config USB_CONFIGFS_F_TCM
 	  Both protocols can work on USB2.0 and USB3.0.
 	  UAS utilizes the USB 3.0 feature called streams support.
 
+config USB_CONFIGFS_F_GUD_DRM
+	bool "Generic USB Display Gadget function"
+	depends on USB_CONFIGFS
+	depends on DRM
+	select DRM_GUD_GADGET
+	select USB_F_GUD_DRM
+	help
+	  This presents a DRM display device as a Generic USB Display.
+
 source "drivers/usb/gadget/legacy/Kconfig"
 
 endif # USB_GADGET
diff --git a/drivers/usb/gadget/function/Makefile b/drivers/usb/gadget/function/Makefile
index 5d3a6cf02218..cd71caa2a34c 100644
--- a/drivers/usb/gadget/function/Makefile
+++ b/drivers/usb/gadget/function/Makefile
@@ -50,3 +50,5 @@ usb_f_printer-y			:= f_printer.o
 obj-$(CONFIG_USB_F_PRINTER)	+= usb_f_printer.o
 usb_f_tcm-y			:= f_tcm.o
 obj-$(CONFIG_USB_F_TCM)		+= usb_f_tcm.o
+usb_f_gud_drm-y			:= f_gud_drm.o
+obj-$(CONFIG_USB_F_GUD_DRM)	+= usb_f_gud_drm.o
diff --git a/drivers/usb/gadget/function/f_gud_drm.c b/drivers/usb/gadget/function/f_gud_drm.c
new file mode 100644
index 000000000000..9a2d6bb9739f
--- /dev/null
+++ b/drivers/usb/gadget/function/f_gud_drm.c
@@ -0,0 +1,678 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Noralf Trønnes
+ */
+
+#include <linux/configfs.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/usb/composite.h>
+#include <linux/usb/gadget.h>
+#include <linux/workqueue.h>
+
+#include <drm/gud_drm.h>
+
+struct f_gud_drm {
+	struct usb_function func;
+	struct work_struct worker;
+	size_t max_buffer_size;
+	void *ctrl_req_buf;
+
+	u8 interface_id;
+	struct usb_request *ctrl_req;
+
+	struct usb_ep *bulk_ep;
+	struct usb_request *bulk_req;
+
+	struct gud_drm_gadget *gdg;
+
+	spinlock_t lock; /* Protects the following members: */
+	bool ctrl_pending;
+	bool status_pending;
+	bool bulk_pending;
+	bool disable_pending;
+	u8 errno;
+	u16 request;
+	u16 value;
+};
+
+static inline struct f_gud_drm *func_to_f_gud_drm(struct usb_function *f)
+{
+	return container_of(f, struct f_gud_drm, func);
+}
+
+struct f_gud_drm_opts {
+	struct usb_function_instance func_inst;
+	struct mutex lock;
+	int refcnt;
+
+	unsigned int drm_dev;
+	const char *backlight_dev;
+};
+
+static inline struct f_gud_drm_opts *fi_to_f_gud_drm_opts(const struct usb_function_instance *fi)
+{
+	return container_of(fi, struct f_gud_drm_opts, func_inst);
+}
+
+static inline struct f_gud_drm_opts *ci_to_f_gud_drm_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_gud_drm_opts,
+			    func_inst.group);
+}
+
+#define F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(name, addr, size)	\
+	static struct usb_endpoint_descriptor name = {		\
+		.bLength =		USB_DT_ENDPOINT_SIZE,	\
+		.bDescriptorType =	USB_DT_ENDPOINT,	\
+		.bEndpointAddress =	addr,			\
+		.bmAttributes =		USB_ENDPOINT_XFER_BULK,	\
+		.wMaxPacketSize =	cpu_to_le16(size),	\
+	}
+
+static struct usb_interface_descriptor f_gud_drm_intf = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	.bNumEndpoints =	1,
+	.bInterfaceClass =	USB_CLASS_VENDOR_SPEC,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_fs_out_desc, USB_DIR_OUT, 0);
+
+static struct usb_descriptor_header *f_gud_drm_fs_function[] = {
+	(struct usb_descriptor_header *)&f_gud_drm_intf,
+	(struct usb_descriptor_header *)&f_gud_drm_fs_out_desc,
+	NULL,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_hs_out_desc, USB_DIR_OUT, 512);
+
+static struct usb_descriptor_header *f_gud_drm_hs_function[] = {
+	(struct usb_descriptor_header *)&f_gud_drm_intf,
+	(struct usb_descriptor_header *)&f_gud_drm_hs_out_desc,
+	NULL,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_ss_out_desc, USB_DIR_OUT, 1024);
+
+static struct usb_ss_ep_comp_descriptor f_gud_drm_ss_bulk_comp_desc = {
+	.bLength =		USB_DT_SS_EP_COMP_SIZE,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+};
+
+static struct usb_descriptor_header *f_gud_drm_ss_function[] = {
+	(struct usb_descriptor_header *)&f_gud_drm_intf,
+	(struct usb_descriptor_header *)&f_gud_drm_ss_out_desc,
+	(struct usb_descriptor_header *)&f_gud_drm_ss_bulk_comp_desc,
+	NULL,
+};
+
+static struct usb_string f_gud_drm_string_defs[] = {
+	[0].s = "Generic USB Display",
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings f_gud_drm_string_table = {
+	.language =	0x0409,	/* en-us */
+	.strings =	f_gud_drm_string_defs,
+};
+
+static struct usb_gadget_strings *f_gud_drm_strings[] = {
+	&f_gud_drm_string_table,
+	NULL,
+};
+
+static void f_gud_drm_bulk_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_gud_drm *fgd = req->context;
+	unsigned long flags;
+
+	if (req->status || req->actual != req->length)
+		return;
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	fgd->bulk_pending = true;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	queue_work(system_long_wq, &fgd->worker);
+}
+
+static int f_gud_drm_ctrl_req_set_buffer(struct f_gud_drm *fgd, void *buf, size_t len)
+{
+	int ret;
+
+	if (len != sizeof(struct gud_drm_req_set_buffer))
+		return -EINVAL;
+
+	ret = gud_drm_gadget_set_buffer(fgd->gdg, buf);
+	if (ret < 0)
+		return ret;
+
+	if (ret > fgd->max_buffer_size)
+		return -EOVERFLOW;
+
+	fgd->bulk_req->length = ret;
+
+	return usb_ep_queue(fgd->bulk_ep, fgd->bulk_req, GFP_KERNEL);
+}
+
+static void f_gud_drm_worker(struct work_struct *work)
+{
+	struct f_gud_drm *fgd = container_of(work, struct f_gud_drm, worker);
+	bool ctrl_pending, bulk_pending, disable_pending;
+	struct gud_drm_gadget *gdg = fgd->gdg;
+	unsigned long flags;
+	u16 request, value;
+	int ret;
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	request = fgd->request;
+	value = fgd->value;
+	ctrl_pending = fgd->ctrl_pending;
+	bulk_pending = fgd->bulk_pending;
+	disable_pending = fgd->disable_pending;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	pr_debug("%s: bulk_pending=%u ctrl_pending=%u disable_pending=%u\n",
+		 __func__, bulk_pending, ctrl_pending, disable_pending);
+
+	if (disable_pending) {
+		gud_drm_gadget_disable_pipe(gdg);
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		fgd->disable_pending = false;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+		return;
+	}
+
+	if (bulk_pending) {
+		struct usb_request *req = fgd->bulk_req;
+
+		ret = gud_drm_gadget_write_buffer(gdg, req->buf, req->actual);
+		if (ret)
+			pr_err("%s: Failed to write buffer, error=%d\n", __func__, ret);
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		fgd->bulk_pending = false;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+	}
+
+	if (ctrl_pending) {
+		unsigned int length = fgd->ctrl_req->length;
+		void *buf = fgd->ctrl_req->buf;
+
+		if (request == GUD_DRM_USB_REQ_SET_BUFFER)
+			ret = f_gud_drm_ctrl_req_set_buffer(fgd, buf, length);
+		else
+			ret = gud_drm_gadget_ctrl_set(gdg, request, value, buf, length);
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		if (!fgd->errno) /* Don't scribble over an EBUSY or ESHUTDOWN */
+			fgd->errno = -ret;
+		fgd->ctrl_pending = false;
+		fgd->status_pending = false;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+	}
+}
+
+static void f_gud_drm_ctrl_req_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_gud_drm *fgd = req->context;
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&fgd->lock, flags);
+
+	if (req->status)
+		ret = req->status;
+	else if (req->actual != req->length)
+		ret = -EREMOTEIO;
+	if (ret) {
+		fgd->errno = -ret;
+		fgd->status_pending = false;
+	} else {
+		fgd->ctrl_pending = true;
+	}
+
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	if (!ret)
+		queue_work(system_long_wq, &fgd->worker);
+}
+
+static int f_gud_drm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	bool in = ctrl->bRequestType & USB_DIR_IN;
+	u16 length = le16_to_cpu(ctrl->wLength);
+	u16 value = le16_to_cpu(ctrl->wValue);
+	unsigned long flags;
+	int ret;
+
+	if (ctrl->bRequest == USB_REQ_GET_STATUS) {
+		struct gud_drm_req_get_status *status = cdev->req->buf;
+
+		if (!in || length != sizeof(*status))
+			return -EINVAL;
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		status->flags = 0;
+		if (fgd->status_pending)
+			status->flags |= GUD_DRM_STATUS_PENDING;
+		status->errno = fgd->errno;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+	} else if (in) {
+		if (length > USB_COMP_EP0_BUFSIZ) /* 4k */
+			return -EOVERFLOW;
+
+		ret = gud_drm_gadget_ctrl_get(fgd->gdg, ctrl->bRequest, value,
+					      cdev->req->buf, length);
+		spin_lock_irqsave(&fgd->lock, flags);
+		fgd->status_pending = false;
+		fgd->errno = ret < 0 ? -ret : 0;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+		if (ret < 0)
+			return ret;
+
+		length = ret;
+	} else {
+		if (length > GUD_DRM_MAX_TRANSFER_SIZE)
+			return -EOVERFLOW;
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		if (fgd->ctrl_pending) {
+			/* If we get here the host has timed out on the previous request */
+			ret = -EBUSY;
+			fgd->status_pending = false;
+			fgd->errno = -ret;
+		} else {
+			ret = 0;
+			fgd->errno = 0;
+			fgd->request = ctrl->bRequest;
+			fgd->value = value;
+			fgd->status_pending = true;
+		}
+		spin_unlock_irqrestore(&fgd->lock, flags);
+
+		if (ret)
+			return ret;
+
+		fgd->ctrl_req->length = length;
+
+		return usb_ep_queue(cdev->gadget->ep0, fgd->ctrl_req, GFP_ATOMIC);
+	}
+
+	cdev->req->length = length;
+
+	return usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);
+}
+
+static bool f_gud_drm_req_match(struct usb_function *f, const struct usb_ctrlrequest *ctrl,
+				bool config0)
+{
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+
+	if (config0)
+		return false;
+
+	if ((ctrl->bRequestType & USB_TYPE_MASK) != USB_TYPE_VENDOR)
+		return false;
+
+	if ((ctrl->bRequestType & USB_RECIP_MASK) != USB_RECIP_INTERFACE)
+		return false;
+
+	return fgd->interface_id == le16_to_cpu(ctrl->wIndex);
+}
+
+static int f_gud_drm_set_alt(struct usb_function *f, unsigned int intf, unsigned int alt)
+{
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	unsigned long flags;
+
+	if (alt || intf != fgd->interface_id)
+		return -EINVAL;
+
+	if (!fgd->bulk_ep->desc) {
+		pr_debug("%s: init\n", __func__);
+		if (config_ep_by_speed(cdev->gadget, f, fgd->bulk_ep)) {
+			fgd->bulk_ep->desc = NULL;
+			return -EINVAL;
+		}
+	}
+
+	pr_debug("%s: reset\n", __func__);
+
+	usb_ep_disable(fgd->bulk_ep);
+	usb_ep_enable(fgd->bulk_ep);
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	fgd->ctrl_pending = false;
+	fgd->bulk_pending = false;
+	fgd->disable_pending = false;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	return 0;
+}
+
+static void f_gud_drm_disable(struct usb_function *f)
+{
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	unsigned long flags;
+
+	pr_debug("%s\n", __func__);
+
+	usb_ep_disable(fgd->bulk_ep);
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	fgd->ctrl_pending = false;
+	fgd->bulk_pending = false;
+	fgd->status_pending = false;
+	fgd->disable_pending = true;
+	fgd->errno = ESHUTDOWN;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	queue_work(system_long_wq, &fgd->worker);
+}
+
+static void f_gud_drm_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	struct usb_composite_dev *cdev = fgd->func.config->cdev;
+
+	flush_work(&fgd->worker);
+
+	gud_drm_gadget_fini(fgd->gdg);
+	fgd->gdg = NULL;
+
+	kfree(fgd->bulk_req->buf);
+	usb_ep_free_request(fgd->bulk_ep, fgd->bulk_req);
+	usb_ep_free_request(cdev->gadget->ep0, fgd->ctrl_req);
+	fgd->ctrl_req = NULL;
+	fgd->bulk_req = NULL;
+	fgd->bulk_ep = NULL;
+
+	usb_free_all_descriptors(f);
+}
+
+static int f_gud_drm_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(f->fi);
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	struct usb_request *ctrl_req, *bulk_req;
+	struct gud_drm_gadget *gdg;
+	struct usb_string *us;
+	void *buf;
+	int ret;
+
+	us = usb_gstrings_attach(cdev, f_gud_drm_strings,
+				 ARRAY_SIZE(f_gud_drm_string_defs));
+	if (IS_ERR(us))
+		return PTR_ERR(us);
+
+	f_gud_drm_intf.iInterface = us[0].id;
+
+	ret = usb_interface_id(c, f);
+	if (ret < 0)
+		return ret;
+
+	fgd->interface_id = ret;
+	f_gud_drm_intf.bInterfaceNumber = fgd->interface_id;
+
+	fgd->bulk_ep = usb_ep_autoconfig(cdev->gadget, &f_gud_drm_fs_out_desc);
+	if (!fgd->bulk_ep)
+		return -ENODEV;
+
+	f_gud_drm_hs_out_desc.bEndpointAddress = f_gud_drm_fs_out_desc.bEndpointAddress;
+
+	f_gud_drm_ss_out_desc.bEndpointAddress = f_gud_drm_fs_out_desc.bEndpointAddress;
+
+	ret = usb_assign_descriptors(f, f_gud_drm_fs_function, f_gud_drm_hs_function,
+				     f_gud_drm_ss_function, NULL);
+	if (ret)
+		return ret;
+
+	ctrl_req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
+	if (!ctrl_req) {
+		ret = -ENOMEM;
+		goto fail_free_descs;
+	}
+
+	ctrl_req->buf = fgd->ctrl_req_buf;
+	ctrl_req->complete = f_gud_drm_ctrl_req_complete;
+	ctrl_req->context = fgd;
+
+	gdg = gud_drm_gadget_init(opts->drm_dev, opts->backlight_dev, &fgd->max_buffer_size);
+	if (IS_ERR(gdg)) {
+		ret = PTR_ERR(gdg);
+		goto fail_free_ctrl_req;
+	}
+
+	bulk_req = usb_ep_alloc_request(fgd->bulk_ep, GFP_KERNEL);
+	if (!bulk_req) {
+		ret = -ENOMEM;
+		goto fail_free_ctrl_req;
+	}
+
+	buf = kmalloc(fgd->max_buffer_size, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto fail_free_bulk_req;
+	}
+
+	bulk_req->complete = f_gud_drm_bulk_complete;
+	bulk_req->context = fgd;
+	bulk_req->buf = buf;
+
+	fgd->ctrl_req = ctrl_req;
+	fgd->bulk_req = bulk_req;
+	fgd->gdg = gdg;
+
+	return 0;
+
+fail_free_bulk_req:
+	usb_ep_free_request(fgd->bulk_ep, bulk_req);
+fail_free_ctrl_req:
+	usb_ep_free_request(cdev->gadget->ep0, ctrl_req);
+fail_free_descs:
+	usb_free_all_descriptors(f);
+
+	return ret;
+}
+
+static void f_gud_drm_free_func(struct usb_function *f)
+{
+	struct f_gud_drm_opts *opts = container_of(f->fi, struct f_gud_drm_opts, func_inst);
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+
+	mutex_lock(&opts->lock);
+	opts->refcnt--;
+	mutex_unlock(&opts->lock);
+
+	kfree(fgd->ctrl_req_buf);
+	kfree(fgd);
+}
+
+static struct usb_function *f_gud_drm_alloc_func(struct usb_function_instance *fi)
+{
+	struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(fi);
+	struct usb_function *func;
+	struct f_gud_drm *fgd;
+
+	fgd = kzalloc(sizeof(*fgd), GFP_KERNEL);
+	if (!fgd)
+		return ERR_PTR(-ENOMEM);
+
+	fgd->ctrl_req_buf = kmalloc(GUD_DRM_MAX_TRANSFER_SIZE, GFP_KERNEL);
+	if (!fgd->ctrl_req_buf)
+		goto error;
+
+	spin_lock_init(&fgd->lock);
+	INIT_WORK(&fgd->worker, f_gud_drm_worker);
+
+	mutex_lock(&opts->lock);
+	opts->refcnt++;
+	mutex_unlock(&opts->lock);
+
+	func = &fgd->func;
+	func->name = "gud_drm";
+	func->bind = f_gud_drm_bind;
+	func->unbind = f_gud_drm_unbind;
+	func->set_alt = f_gud_drm_set_alt;
+	func->req_match = f_gud_drm_req_match;
+	func->setup = f_gud_drm_setup;
+	func->disable = f_gud_drm_disable;
+	func->free_func = f_gud_drm_free_func;
+
+	return func;
+
+error:
+	kfree(fgd);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+static ssize_t f_gud_drm_opts_drm_dev_show(struct config_item *item, char *page)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	int result;
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%u\n", opts->drm_dev);
+	mutex_unlock(&opts->lock);
+
+	return result;
+}
+
+static ssize_t f_gud_drm_opts_drm_dev_store(struct config_item *item,
+					    const char *page, size_t len)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	unsigned int num;
+	int ret;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	ret = kstrtouint(page, 0, &num);
+	if (ret)
+		goto unlock;
+
+	opts->drm_dev = num;
+	ret = len;
+unlock:
+	mutex_unlock(&opts->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR(f_gud_drm_opts_, drm_dev);
+
+static ssize_t f_gud_drm_opts_backlight_dev_show(struct config_item *item, char *page)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	ssize_t ret = 0;
+
+	mutex_lock(&opts->lock);
+	if (opts->backlight_dev)
+		ret = strscpy(page, opts->backlight_dev, PAGE_SIZE);
+	else
+		page[0] = '\0';
+	mutex_unlock(&opts->lock);
+
+	return ret;
+}
+
+static ssize_t f_gud_drm_opts_backlight_dev_store(struct config_item *item,
+						  const char *page, size_t len)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	ssize_t ret;
+	char *name;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	name = kstrndup(page, len, GFP_KERNEL);
+	if (!name) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	kfree(opts->backlight_dev);
+	opts->backlight_dev = name;
+	ret = len;
+unlock:
+	mutex_unlock(&opts->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR(f_gud_drm_opts_, backlight_dev);
+
+static struct configfs_attribute *f_gud_drm_attrs[] = {
+	&f_gud_drm_opts_attr_drm_dev,
+	&f_gud_drm_opts_attr_backlight_dev,
+	NULL,
+};
+
+static void f_gud_drm_attr_release(struct config_item *item)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations f_gud_drm_item_ops = {
+	.release	= f_gud_drm_attr_release,
+};
+
+static const struct config_item_type f_gud_drm_func_type = {
+	.ct_item_ops	= &f_gud_drm_item_ops,
+	.ct_attrs	= f_gud_drm_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static void f_gud_drm_free_func_inst(struct usb_function_instance *fi)
+{
+	struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(fi);
+
+	mutex_destroy(&opts->lock);
+	kfree(opts->backlight_dev);
+	kfree(opts);
+}
+
+static struct usb_function_instance *f_gud_drm_alloc_func_inst(void)
+{
+	struct f_gud_drm_opts *opts;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&opts->lock);
+	opts->func_inst.free_func_inst = f_gud_drm_free_func_inst;
+
+	config_group_init_type_name(&opts->func_inst.group, "", &f_gud_drm_func_type);
+
+	return &opts->func_inst;
+}
+
+DECLARE_USB_FUNCTION_INIT(gud_drm, f_gud_drm_alloc_func_inst, f_gud_drm_alloc_func);
+
+MODULE_DESCRIPTION("Generic USB Display Gadget");
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");
-- 
2.23.0

[PATCH v2 10/10] usb: gadget: function: Add Generic USB Display support

[Noralf Trønnes]

This adds the gadget side support for the Generic USB Display. It presents
a DRM display device as a USB Display configured through configfs.

The display is implemented as a vendor type USB interface with one bulk
out endpoint. The protocol is implemented using control requests.
lz4 compressed framebuffer data/pixels are sent over the bulk endpoint.

The DRM part of the gadget is placed in the DRM subsystem since it reaches
into the DRM internals.

Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 .../ABI/testing/configfs-usb-gadget-gud_drm   |  10 +
 MAINTAINERS                                   |   2 +
 drivers/usb/gadget/Kconfig                    |  12 +
 drivers/usb/gadget/function/Makefile          |   2 +
 drivers/usb/gadget/function/f_gud_drm.c       | 678 ++++++++++++++++++
 5 files changed, 704 insertions(+)
 create mode 100644 Documentation/ABI/testing/configfs-usb-gadget-gud_drm
 create mode 100644 drivers/usb/gadget/function/f_gud_drm.c

diff --git a/Documentation/ABI/testing/configfs-usb-gadget-gud_drm b/Documentation/ABI/testing/configfs-usb-gadget-gud_drm
new file mode 100644
index 000000000000..4f865e7fea58
--- /dev/null
+++ b/Documentation/ABI/testing/configfs-usb-gadget-gud_drm
@@ -0,0 +1,10 @@
+What:		/config/usb-gadget/gadget/functions/gud_drm.name
+Date:		May 2020
+KernelVersion:	5.9
+Description:
+		The attributes:
+
+		drm_dev - DRM device number
+		backlight_dev - Backlight device name (optional)
+				The backlight brightness scale should be
+				perceptual not linear.
diff --git a/MAINTAINERS b/MAINTAINERS
index 7494a21ea41e..4bc5dc7296b8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5296,7 +5296,9 @@ M:	Noralf Trønnes <noralf@tronnes.org>
 S:	Maintained
 W:	https://github.com/notro/gud/wiki
 T:	git git://anongit.freedesktop.org/drm/drm-misc
+F:	Documentation/ABI/testing/configfs-usb-gadget-gud_drm
 F:	drivers/gpu/drm/gud/
+F:	drivers/usb/gadget/function/f_gud_drm.c
 F:	include/drm/gud_drm.h
 
 DRM DRIVER FOR GRAIN MEDIA GM12U320 PROJECTORS
diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index c6db0a0a340c..8d90add495b6 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -216,6 +216,9 @@ config USB_F_PRINTER
 config USB_F_TCM
 	tristate
 
+config USB_F_GUD_DRM
+	tristate
+
 # this first set of drivers all depend on bulk-capable hardware.
 
 config USB_CONFIGFS
@@ -483,6 +486,15 @@ config USB_CONFIGFS_F_TCM
 	  Both protocols can work on USB2.0 and USB3.0.
 	  UAS utilizes the USB 3.0 feature called streams support.
 
+config USB_CONFIGFS_F_GUD_DRM
+	bool "Generic USB Display Gadget function"
+	depends on USB_CONFIGFS
+	depends on DRM
+	select DRM_GUD_GADGET
+	select USB_F_GUD_DRM
+	help
+	  This presents a DRM display device as a Generic USB Display.
+
 source "drivers/usb/gadget/legacy/Kconfig"
 
 endif # USB_GADGET
diff --git a/drivers/usb/gadget/function/Makefile b/drivers/usb/gadget/function/Makefile
index 5d3a6cf02218..cd71caa2a34c 100644
--- a/drivers/usb/gadget/function/Makefile
+++ b/drivers/usb/gadget/function/Makefile
@@ -50,3 +50,5 @@ usb_f_printer-y			:= f_printer.o
 obj-$(CONFIG_USB_F_PRINTER)	+= usb_f_printer.o
 usb_f_tcm-y			:= f_tcm.o
 obj-$(CONFIG_USB_F_TCM)		+= usb_f_tcm.o
+usb_f_gud_drm-y			:= f_gud_drm.o
+obj-$(CONFIG_USB_F_GUD_DRM)	+= usb_f_gud_drm.o
diff --git a/drivers/usb/gadget/function/f_gud_drm.c b/drivers/usb/gadget/function/f_gud_drm.c
new file mode 100644
index 000000000000..9a2d6bb9739f
--- /dev/null
+++ b/drivers/usb/gadget/function/f_gud_drm.c
@@ -0,0 +1,678 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020 Noralf Trønnes
+ */
+
+#include <linux/configfs.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/usb/composite.h>
+#include <linux/usb/gadget.h>
+#include <linux/workqueue.h>
+
+#include <drm/gud_drm.h>
+
+struct f_gud_drm {
+	struct usb_function func;
+	struct work_struct worker;
+	size_t max_buffer_size;
+	void *ctrl_req_buf;
+
+	u8 interface_id;
+	struct usb_request *ctrl_req;
+
+	struct usb_ep *bulk_ep;
+	struct usb_request *bulk_req;
+
+	struct gud_drm_gadget *gdg;
+
+	spinlock_t lock; /* Protects the following members: */
+	bool ctrl_pending;
+	bool status_pending;
+	bool bulk_pending;
+	bool disable_pending;
+	u8 errno;
+	u16 request;
+	u16 value;
+};
+
+static inline struct f_gud_drm *func_to_f_gud_drm(struct usb_function *f)
+{
+	return container_of(f, struct f_gud_drm, func);
+}
+
+struct f_gud_drm_opts {
+	struct usb_function_instance func_inst;
+	struct mutex lock;
+	int refcnt;
+
+	unsigned int drm_dev;
+	const char *backlight_dev;
+};
+
+static inline struct f_gud_drm_opts *fi_to_f_gud_drm_opts(const struct usb_function_instance *fi)
+{
+	return container_of(fi, struct f_gud_drm_opts, func_inst);
+}
+
+static inline struct f_gud_drm_opts *ci_to_f_gud_drm_opts(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct f_gud_drm_opts,
+			    func_inst.group);
+}
+
+#define F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(name, addr, size)	\
+	static struct usb_endpoint_descriptor name = {		\
+		.bLength =		USB_DT_ENDPOINT_SIZE,	\
+		.bDescriptorType =	USB_DT_ENDPOINT,	\
+		.bEndpointAddress =	addr,			\
+		.bmAttributes =		USB_ENDPOINT_XFER_BULK,	\
+		.wMaxPacketSize =	cpu_to_le16(size),	\
+	}
+
+static struct usb_interface_descriptor f_gud_drm_intf = {
+	.bLength =		USB_DT_INTERFACE_SIZE,
+	.bDescriptorType =	USB_DT_INTERFACE,
+	.bNumEndpoints =	1,
+	.bInterfaceClass =	USB_CLASS_VENDOR_SPEC,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_fs_out_desc, USB_DIR_OUT, 0);
+
+static struct usb_descriptor_header *f_gud_drm_fs_function[] = {
+	(struct usb_descriptor_header *)&f_gud_drm_intf,
+	(struct usb_descriptor_header *)&f_gud_drm_fs_out_desc,
+	NULL,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_hs_out_desc, USB_DIR_OUT, 512);
+
+static struct usb_descriptor_header *f_gud_drm_hs_function[] = {
+	(struct usb_descriptor_header *)&f_gud_drm_intf,
+	(struct usb_descriptor_header *)&f_gud_drm_hs_out_desc,
+	NULL,
+};
+
+F_MUD_DEFINE_BULK_ENDPOINT_DESCRIPTOR(f_gud_drm_ss_out_desc, USB_DIR_OUT, 1024);
+
+static struct usb_ss_ep_comp_descriptor f_gud_drm_ss_bulk_comp_desc = {
+	.bLength =		USB_DT_SS_EP_COMP_SIZE,
+	.bDescriptorType =	USB_DT_SS_ENDPOINT_COMP,
+};
+
+static struct usb_descriptor_header *f_gud_drm_ss_function[] = {
+	(struct usb_descriptor_header *)&f_gud_drm_intf,
+	(struct usb_descriptor_header *)&f_gud_drm_ss_out_desc,
+	(struct usb_descriptor_header *)&f_gud_drm_ss_bulk_comp_desc,
+	NULL,
+};
+
+static struct usb_string f_gud_drm_string_defs[] = {
+	[0].s = "Generic USB Display",
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings f_gud_drm_string_table = {
+	.language =	0x0409,	/* en-us */
+	.strings =	f_gud_drm_string_defs,
+};
+
+static struct usb_gadget_strings *f_gud_drm_strings[] = {
+	&f_gud_drm_string_table,
+	NULL,
+};
+
+static void f_gud_drm_bulk_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_gud_drm *fgd = req->context;
+	unsigned long flags;
+
+	if (req->status || req->actual != req->length)
+		return;
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	fgd->bulk_pending = true;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	queue_work(system_long_wq, &fgd->worker);
+}
+
+static int f_gud_drm_ctrl_req_set_buffer(struct f_gud_drm *fgd, void *buf, size_t len)
+{
+	int ret;
+
+	if (len != sizeof(struct gud_drm_req_set_buffer))
+		return -EINVAL;
+
+	ret = gud_drm_gadget_set_buffer(fgd->gdg, buf);
+	if (ret < 0)
+		return ret;
+
+	if (ret > fgd->max_buffer_size)
+		return -EOVERFLOW;
+
+	fgd->bulk_req->length = ret;
+
+	return usb_ep_queue(fgd->bulk_ep, fgd->bulk_req, GFP_KERNEL);
+}
+
+static void f_gud_drm_worker(struct work_struct *work)
+{
+	struct f_gud_drm *fgd = container_of(work, struct f_gud_drm, worker);
+	bool ctrl_pending, bulk_pending, disable_pending;
+	struct gud_drm_gadget *gdg = fgd->gdg;
+	unsigned long flags;
+	u16 request, value;
+	int ret;
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	request = fgd->request;
+	value = fgd->value;
+	ctrl_pending = fgd->ctrl_pending;
+	bulk_pending = fgd->bulk_pending;
+	disable_pending = fgd->disable_pending;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	pr_debug("%s: bulk_pending=%u ctrl_pending=%u disable_pending=%u\n",
+		 __func__, bulk_pending, ctrl_pending, disable_pending);
+
+	if (disable_pending) {
+		gud_drm_gadget_disable_pipe(gdg);
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		fgd->disable_pending = false;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+		return;
+	}
+
+	if (bulk_pending) {
+		struct usb_request *req = fgd->bulk_req;
+
+		ret = gud_drm_gadget_write_buffer(gdg, req->buf, req->actual);
+		if (ret)
+			pr_err("%s: Failed to write buffer, error=%d\n", __func__, ret);
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		fgd->bulk_pending = false;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+	}
+
+	if (ctrl_pending) {
+		unsigned int length = fgd->ctrl_req->length;
+		void *buf = fgd->ctrl_req->buf;
+
+		if (request == GUD_DRM_USB_REQ_SET_BUFFER)
+			ret = f_gud_drm_ctrl_req_set_buffer(fgd, buf, length);
+		else
+			ret = gud_drm_gadget_ctrl_set(gdg, request, value, buf, length);
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		if (!fgd->errno) /* Don't scribble over an EBUSY or ESHUTDOWN */
+			fgd->errno = -ret;
+		fgd->ctrl_pending = false;
+		fgd->status_pending = false;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+	}
+}
+
+static void f_gud_drm_ctrl_req_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	struct f_gud_drm *fgd = req->context;
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&fgd->lock, flags);
+
+	if (req->status)
+		ret = req->status;
+	else if (req->actual != req->length)
+		ret = -EREMOTEIO;
+	if (ret) {
+		fgd->errno = -ret;
+		fgd->status_pending = false;
+	} else {
+		fgd->ctrl_pending = true;
+	}
+
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	if (!ret)
+		queue_work(system_long_wq, &fgd->worker);
+}
+
+static int f_gud_drm_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl)
+{
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	bool in = ctrl->bRequestType & USB_DIR_IN;
+	u16 length = le16_to_cpu(ctrl->wLength);
+	u16 value = le16_to_cpu(ctrl->wValue);
+	unsigned long flags;
+	int ret;
+
+	if (ctrl->bRequest == USB_REQ_GET_STATUS) {
+		struct gud_drm_req_get_status *status = cdev->req->buf;
+
+		if (!in || length != sizeof(*status))
+			return -EINVAL;
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		status->flags = 0;
+		if (fgd->status_pending)
+			status->flags |= GUD_DRM_STATUS_PENDING;
+		status->errno = fgd->errno;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+	} else if (in) {
+		if (length > USB_COMP_EP0_BUFSIZ) /* 4k */
+			return -EOVERFLOW;
+
+		ret = gud_drm_gadget_ctrl_get(fgd->gdg, ctrl->bRequest, value,
+					      cdev->req->buf, length);
+		spin_lock_irqsave(&fgd->lock, flags);
+		fgd->status_pending = false;
+		fgd->errno = ret < 0 ? -ret : 0;
+		spin_unlock_irqrestore(&fgd->lock, flags);
+		if (ret < 0)
+			return ret;
+
+		length = ret;
+	} else {
+		if (length > GUD_DRM_MAX_TRANSFER_SIZE)
+			return -EOVERFLOW;
+
+		spin_lock_irqsave(&fgd->lock, flags);
+		if (fgd->ctrl_pending) {
+			/* If we get here the host has timed out on the previous request */
+			ret = -EBUSY;
+			fgd->status_pending = false;
+			fgd->errno = -ret;
+		} else {
+			ret = 0;
+			fgd->errno = 0;
+			fgd->request = ctrl->bRequest;
+			fgd->value = value;
+			fgd->status_pending = true;
+		}
+		spin_unlock_irqrestore(&fgd->lock, flags);
+
+		if (ret)
+			return ret;
+
+		fgd->ctrl_req->length = length;
+
+		return usb_ep_queue(cdev->gadget->ep0, fgd->ctrl_req, GFP_ATOMIC);
+	}
+
+	cdev->req->length = length;
+
+	return usb_ep_queue(cdev->gadget->ep0, cdev->req, GFP_ATOMIC);
+}
+
+static bool f_gud_drm_req_match(struct usb_function *f, const struct usb_ctrlrequest *ctrl,
+				bool config0)
+{
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+
+	if (config0)
+		return false;
+
+	if ((ctrl->bRequestType & USB_TYPE_MASK) != USB_TYPE_VENDOR)
+		return false;
+
+	if ((ctrl->bRequestType & USB_RECIP_MASK) != USB_RECIP_INTERFACE)
+		return false;
+
+	return fgd->interface_id == le16_to_cpu(ctrl->wIndex);
+}
+
+static int f_gud_drm_set_alt(struct usb_function *f, unsigned int intf, unsigned int alt)
+{
+	struct usb_composite_dev *cdev = f->config->cdev;
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	unsigned long flags;
+
+	if (alt || intf != fgd->interface_id)
+		return -EINVAL;
+
+	if (!fgd->bulk_ep->desc) {
+		pr_debug("%s: init\n", __func__);
+		if (config_ep_by_speed(cdev->gadget, f, fgd->bulk_ep)) {
+			fgd->bulk_ep->desc = NULL;
+			return -EINVAL;
+		}
+	}
+
+	pr_debug("%s: reset\n", __func__);
+
+	usb_ep_disable(fgd->bulk_ep);
+	usb_ep_enable(fgd->bulk_ep);
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	fgd->ctrl_pending = false;
+	fgd->bulk_pending = false;
+	fgd->disable_pending = false;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	return 0;
+}
+
+static void f_gud_drm_disable(struct usb_function *f)
+{
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	unsigned long flags;
+
+	pr_debug("%s\n", __func__);
+
+	usb_ep_disable(fgd->bulk_ep);
+
+	spin_lock_irqsave(&fgd->lock, flags);
+	fgd->ctrl_pending = false;
+	fgd->bulk_pending = false;
+	fgd->status_pending = false;
+	fgd->disable_pending = true;
+	fgd->errno = ESHUTDOWN;
+	spin_unlock_irqrestore(&fgd->lock, flags);
+
+	queue_work(system_long_wq, &fgd->worker);
+}
+
+static void f_gud_drm_unbind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	struct usb_composite_dev *cdev = fgd->func.config->cdev;
+
+	flush_work(&fgd->worker);
+
+	gud_drm_gadget_fini(fgd->gdg);
+	fgd->gdg = NULL;
+
+	kfree(fgd->bulk_req->buf);
+	usb_ep_free_request(fgd->bulk_ep, fgd->bulk_req);
+	usb_ep_free_request(cdev->gadget->ep0, fgd->ctrl_req);
+	fgd->ctrl_req = NULL;
+	fgd->bulk_req = NULL;
+	fgd->bulk_ep = NULL;
+
+	usb_free_all_descriptors(f);
+}
+
+static int f_gud_drm_bind(struct usb_configuration *c, struct usb_function *f)
+{
+	struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(f->fi);
+	struct usb_composite_dev *cdev = c->cdev;
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+	struct usb_request *ctrl_req, *bulk_req;
+	struct gud_drm_gadget *gdg;
+	struct usb_string *us;
+	void *buf;
+	int ret;
+
+	us = usb_gstrings_attach(cdev, f_gud_drm_strings,
+				 ARRAY_SIZE(f_gud_drm_string_defs));
+	if (IS_ERR(us))
+		return PTR_ERR(us);
+
+	f_gud_drm_intf.iInterface = us[0].id;
+
+	ret = usb_interface_id(c, f);
+	if (ret < 0)
+		return ret;
+
+	fgd->interface_id = ret;
+	f_gud_drm_intf.bInterfaceNumber = fgd->interface_id;
+
+	fgd->bulk_ep = usb_ep_autoconfig(cdev->gadget, &f_gud_drm_fs_out_desc);
+	if (!fgd->bulk_ep)
+		return -ENODEV;
+
+	f_gud_drm_hs_out_desc.bEndpointAddress = f_gud_drm_fs_out_desc.bEndpointAddress;
+
+	f_gud_drm_ss_out_desc.bEndpointAddress = f_gud_drm_fs_out_desc.bEndpointAddress;
+
+	ret = usb_assign_descriptors(f, f_gud_drm_fs_function, f_gud_drm_hs_function,
+				     f_gud_drm_ss_function, NULL);
+	if (ret)
+		return ret;
+
+	ctrl_req = usb_ep_alloc_request(cdev->gadget->ep0, GFP_KERNEL);
+	if (!ctrl_req) {
+		ret = -ENOMEM;
+		goto fail_free_descs;
+	}
+
+	ctrl_req->buf = fgd->ctrl_req_buf;
+	ctrl_req->complete = f_gud_drm_ctrl_req_complete;
+	ctrl_req->context = fgd;
+
+	gdg = gud_drm_gadget_init(opts->drm_dev, opts->backlight_dev, &fgd->max_buffer_size);
+	if (IS_ERR(gdg)) {
+		ret = PTR_ERR(gdg);
+		goto fail_free_ctrl_req;
+	}
+
+	bulk_req = usb_ep_alloc_request(fgd->bulk_ep, GFP_KERNEL);
+	if (!bulk_req) {
+		ret = -ENOMEM;
+		goto fail_free_ctrl_req;
+	}
+
+	buf = kmalloc(fgd->max_buffer_size, GFP_KERNEL);
+	if (!buf) {
+		ret = -ENOMEM;
+		goto fail_free_bulk_req;
+	}
+
+	bulk_req->complete = f_gud_drm_bulk_complete;
+	bulk_req->context = fgd;
+	bulk_req->buf = buf;
+
+	fgd->ctrl_req = ctrl_req;
+	fgd->bulk_req = bulk_req;
+	fgd->gdg = gdg;
+
+	return 0;
+
+fail_free_bulk_req:
+	usb_ep_free_request(fgd->bulk_ep, bulk_req);
+fail_free_ctrl_req:
+	usb_ep_free_request(cdev->gadget->ep0, ctrl_req);
+fail_free_descs:
+	usb_free_all_descriptors(f);
+
+	return ret;
+}
+
+static void f_gud_drm_free_func(struct usb_function *f)
+{
+	struct f_gud_drm_opts *opts = container_of(f->fi, struct f_gud_drm_opts, func_inst);
+	struct f_gud_drm *fgd = func_to_f_gud_drm(f);
+
+	mutex_lock(&opts->lock);
+	opts->refcnt--;
+	mutex_unlock(&opts->lock);
+
+	kfree(fgd->ctrl_req_buf);
+	kfree(fgd);
+}
+
+static struct usb_function *f_gud_drm_alloc_func(struct usb_function_instance *fi)
+{
+	struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(fi);
+	struct usb_function *func;
+	struct f_gud_drm *fgd;
+
+	fgd = kzalloc(sizeof(*fgd), GFP_KERNEL);
+	if (!fgd)
+		return ERR_PTR(-ENOMEM);
+
+	fgd->ctrl_req_buf = kmalloc(GUD_DRM_MAX_TRANSFER_SIZE, GFP_KERNEL);
+	if (!fgd->ctrl_req_buf)
+		goto error;
+
+	spin_lock_init(&fgd->lock);
+	INIT_WORK(&fgd->worker, f_gud_drm_worker);
+
+	mutex_lock(&opts->lock);
+	opts->refcnt++;
+	mutex_unlock(&opts->lock);
+
+	func = &fgd->func;
+	func->name = "gud_drm";
+	func->bind = f_gud_drm_bind;
+	func->unbind = f_gud_drm_unbind;
+	func->set_alt = f_gud_drm_set_alt;
+	func->req_match = f_gud_drm_req_match;
+	func->setup = f_gud_drm_setup;
+	func->disable = f_gud_drm_disable;
+	func->free_func = f_gud_drm_free_func;
+
+	return func;
+
+error:
+	kfree(fgd);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+static ssize_t f_gud_drm_opts_drm_dev_show(struct config_item *item, char *page)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	int result;
+
+	mutex_lock(&opts->lock);
+	result = sprintf(page, "%u\n", opts->drm_dev);
+	mutex_unlock(&opts->lock);
+
+	return result;
+}
+
+static ssize_t f_gud_drm_opts_drm_dev_store(struct config_item *item,
+					    const char *page, size_t len)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	unsigned int num;
+	int ret;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	ret = kstrtouint(page, 0, &num);
+	if (ret)
+		goto unlock;
+
+	opts->drm_dev = num;
+	ret = len;
+unlock:
+	mutex_unlock(&opts->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR(f_gud_drm_opts_, drm_dev);
+
+static ssize_t f_gud_drm_opts_backlight_dev_show(struct config_item *item, char *page)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	ssize_t ret = 0;
+
+	mutex_lock(&opts->lock);
+	if (opts->backlight_dev)
+		ret = strscpy(page, opts->backlight_dev, PAGE_SIZE);
+	else
+		page[0] = '\0';
+	mutex_unlock(&opts->lock);
+
+	return ret;
+}
+
+static ssize_t f_gud_drm_opts_backlight_dev_store(struct config_item *item,
+						  const char *page, size_t len)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+	ssize_t ret;
+	char *name;
+
+	mutex_lock(&opts->lock);
+	if (opts->refcnt) {
+		ret = -EBUSY;
+		goto unlock;
+	}
+
+	name = kstrndup(page, len, GFP_KERNEL);
+	if (!name) {
+		ret = -ENOMEM;
+		goto unlock;
+	}
+
+	kfree(opts->backlight_dev);
+	opts->backlight_dev = name;
+	ret = len;
+unlock:
+	mutex_unlock(&opts->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR(f_gud_drm_opts_, backlight_dev);
+
+static struct configfs_attribute *f_gud_drm_attrs[] = {
+	&f_gud_drm_opts_attr_drm_dev,
+	&f_gud_drm_opts_attr_backlight_dev,
+	NULL,
+};
+
+static void f_gud_drm_attr_release(struct config_item *item)
+{
+	struct f_gud_drm_opts *opts = ci_to_f_gud_drm_opts(item);
+
+	usb_put_function_instance(&opts->func_inst);
+}
+
+static struct configfs_item_operations f_gud_drm_item_ops = {
+	.release	= f_gud_drm_attr_release,
+};
+
+static const struct config_item_type f_gud_drm_func_type = {
+	.ct_item_ops	= &f_gud_drm_item_ops,
+	.ct_attrs	= f_gud_drm_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static void f_gud_drm_free_func_inst(struct usb_function_instance *fi)
+{
+	struct f_gud_drm_opts *opts = fi_to_f_gud_drm_opts(fi);
+
+	mutex_destroy(&opts->lock);
+	kfree(opts->backlight_dev);
+	kfree(opts);
+}
+
+static struct usb_function_instance *f_gud_drm_alloc_func_inst(void)
+{
+	struct f_gud_drm_opts *opts;
+
+	opts = kzalloc(sizeof(*opts), GFP_KERNEL);
+	if (!opts)
+		return ERR_PTR(-ENOMEM);
+
+	mutex_init(&opts->lock);
+	opts->func_inst.free_func_inst = f_gud_drm_free_func_inst;
+
+	config_group_init_type_name(&opts->func_inst.group, "", &f_gud_drm_func_type);
+
+	return &opts->func_inst;
+}
+
+DECLARE_USB_FUNCTION_INIT(gud_drm, f_gud_drm_alloc_func_inst, f_gud_drm_alloc_func);
+
+MODULE_DESCRIPTION("Generic USB Display Gadget");
+MODULE_AUTHOR("Noralf Trønnes");
+MODULE_LICENSE("GPL");
-- 
2.23.0

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Re: [PATCH v2 01/10] backlight: Add backlight_device_get_by_name()

[Jingoo Han]

On 5/9/20, 10:16 AM, Noralf Trønnes wrote:
> 
> Add a way to lookup a backlight device based on its name.
> Will be used by a USB display gadget getting the name from configfs.
>
> Cc: Lee Jones <lee.jones@linaro.org>

Please delete this line, because Lee already sent his Acked-by.

> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Jingoo Han <jingoohan1@gmail.com>

Acked-by: Jingoo Han <jingoohan1@gmail.com>

Best regards,
Jingoo Han

> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> Acked-by: Lee Jones <lee.jones@linaro.org>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
 > drivers/video/backlight/backlight.c | 21 +++++++++++++++++++++
 > include/linux/backlight.h           |  1 +
 > 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index cac3e35d7630..92d80aa0c0ef 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -432,6 +432,27 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
>  }
>  EXPORT_SYMBOL(backlight_device_get_by_type);
>  
> +/**
> + * backlight_device_get_by_name - Get backlight device by name
> + * @name: Device name
> + *
> + * This function looks up a backlight device by its name. It obtains a reference
> + * on the backlight device and it is the caller's responsibility to drop the
> + * reference by calling backlight_put().
> + *
> + * Returns:
> + * A pointer to the backlight device if found, otherwise NULL.
> + */
> +struct backlight_device *backlight_device_get_by_name(const char *name)
> +{
> +	struct device *dev;
> +
> +	dev = class_find_device_by_name(backlight_class, name);
> +
> +	return dev ? to_backlight_device(dev) : NULL;
> +}
> +EXPORT_SYMBOL(backlight_device_get_by_name);
> +
>  /**
>   * backlight_device_unregister - unregisters a backlight device object.
>   * @bd: the backlight device object to be unregistered and freed.
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index c7d6b2e8c3b5..56e4580d4f55 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -190,6 +190,7 @@ extern void backlight_force_update(struct backlight_device *bd,
>  extern int backlight_register_notifier(struct notifier_block *nb);
>  extern int backlight_unregister_notifier(struct notifier_block *nb);
>  extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
> +struct backlight_device *backlight_device_get_by_name(const char *name);
>  extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
>  
>  #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
> -- 
> 2.23.0

Re: [PATCH v2 01/10] backlight: Add backlight_device_get_by_name()

[Jingoo Han]

On 5/9/20, 10:16 AM, Noralf Trønnes wrote:
> 
> Add a way to lookup a backlight device based on its name.
> Will be used by a USB display gadget getting the name from configfs.
>
> Cc: Lee Jones <lee.jones@linaro.org>

Please delete this line, because Lee already sent his Acked-by.

> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Jingoo Han <jingoohan1@gmail.com>

Acked-by: Jingoo Han <jingoohan1@gmail.com>

Best regards,
Jingoo Han

> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> Acked-by: Lee Jones <lee.jones@linaro.org>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
 > drivers/video/backlight/backlight.c | 21 +++++++++++++++++++++
 > include/linux/backlight.h           |  1 +
 > 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
> index cac3e35d7630..92d80aa0c0ef 100644
> --- a/drivers/video/backlight/backlight.c
> +++ b/drivers/video/backlight/backlight.c
> @@ -432,6 +432,27 @@ struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
>  }
>  EXPORT_SYMBOL(backlight_device_get_by_type);
>  
> +/**
> + * backlight_device_get_by_name - Get backlight device by name
> + * @name: Device name
> + *
> + * This function looks up a backlight device by its name. It obtains a reference
> + * on the backlight device and it is the caller's responsibility to drop the
> + * reference by calling backlight_put().
> + *
> + * Returns:
> + * A pointer to the backlight device if found, otherwise NULL.
> + */
> +struct backlight_device *backlight_device_get_by_name(const char *name)
> +{
> +	struct device *dev;
> +
> +	dev = class_find_device_by_name(backlight_class, name);
> +
> +	return dev ? to_backlight_device(dev) : NULL;
> +}
> +EXPORT_SYMBOL(backlight_device_get_by_name);
> +
>  /**
>   * backlight_device_unregister - unregisters a backlight device object.
>   * @bd: the backlight device object to be unregistered and freed.
> diff --git a/include/linux/backlight.h b/include/linux/backlight.h
> index c7d6b2e8c3b5..56e4580d4f55 100644
> --- a/include/linux/backlight.h
> +++ b/include/linux/backlight.h
> @@ -190,6 +190,7 @@ extern void backlight_force_update(struct backlight_device *bd,
>  extern int backlight_register_notifier(struct notifier_block *nb);
>  extern int backlight_unregister_notifier(struct notifier_block *nb);
>  extern struct backlight_device *backlight_device_get_by_type(enum backlight_type type);
> +struct backlight_device *backlight_device_get_by_name(const char *name);
>  extern int backlight_device_set_brightness(struct backlight_device *bd, unsigned long brightness);
>  
>  #define to_backlight_device(obj) container_of(obj, struct backlight_device, dev)
> -- 
> 2.23.0

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Re: [PATCH v2 01/10] backlight: Add backlight_device_get_by_name()

[Lee Jones]

On Sat, 09 May 2020, Noralf Trønnes wrote:

> Add a way to lookup a backlight device based on its name.
> Will be used by a USB display gadget getting the name from configfs.
> 
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Jingoo Han <jingoohan1@gmail.com>
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> Acked-by: Lee Jones <lee.jones@linaro.org>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
>  drivers/video/backlight/backlight.c | 21 +++++++++++++++++++++
>  include/linux/backlight.h           |  1 +
>  2 files changed, 22 insertions(+)

Applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [PATCH v2 01/10] backlight: Add backlight_device_get_by_name()

[Lee Jones]

On Sat, 09 May 2020, Noralf Trønnes wrote:

> Add a way to lookup a backlight device based on its name.
> Will be used by a USB display gadget getting the name from configfs.
> 
> Cc: Lee Jones <lee.jones@linaro.org>
> Cc: Daniel Thompson <daniel.thompson@linaro.org>
> Cc: Jingoo Han <jingoohan1@gmail.com>
> Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
> Acked-by: Lee Jones <lee.jones@linaro.org>
> Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
> ---
>  drivers/video/backlight/backlight.c | 21 +++++++++++++++++++++
>  include/linux/backlight.h           |  1 +
>  2 files changed, 22 insertions(+)

Applied, thanks.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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Re: [PATCH v2 03/10] drm/client: Add drm_client_framebuffer_flush()

[Emil Velikov]

Hi all,

I realise this has landed, so a small FYI comment.

On Sat, 9 May 2020 at 15:16, Noralf Trønnes <noralf@tronnes.org> wrote:

> +int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
> +{
> +       if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)

Hmm cannot think of a good reason why anyone would call this with
!buffer || !buffer->fb?
Might be a good idea to WARN in those cases - otherwise the user is
given false sense to security.

Looking at the upcoming user (drm/gud) it already has both - so it's
perfectly safe.

-Emil

Re: [PATCH v2 03/10] drm/client: Add drm_client_framebuffer_flush()

[Emil Velikov]

Hi all,

I realise this has landed, so a small FYI comment.

On Sat, 9 May 2020 at 15:16, Noralf Trønnes <noralf@tronnes.org> wrote:

> +int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
> +{
> +       if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)

Hmm cannot think of a good reason why anyone would call this with
!buffer || !buffer->fb?
Might be a good idea to WARN in those cases - otherwise the user is
given false sense to security.

Looking at the upcoming user (drm/gud) it already has both - so it's
perfectly safe.

-Emil
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Re: [PATCH v2 03/10] drm/client: Add drm_client_framebuffer_flush()

[Noralf Trønnes]

Den 28.05.2020 15.48, skrev Emil Velikov:
> Hi all,
> 
> I realise this has landed, so a small FYI comment.
> 
> On Sat, 9 May 2020 at 15:16, Noralf Trønnes <noralf@tronnes.org> wrote:
> 
>> +int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
>> +{
>> +       if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)
> 
> Hmm cannot think of a good reason why anyone would call this with
> !buffer || !buffer->fb?
> Might be a good idea to WARN in those cases - otherwise the user is
> given false sense to security.
> 

I agree, I'll send a fixup when I get through my backlog.

Noralf.

> Looking at the upcoming user (drm/gud) it already has both - so it's
> perfectly safe.
> 
> -Emil
> 

Re: [PATCH v2 03/10] drm/client: Add drm_client_framebuffer_flush()

[Noralf Trønnes]

Den 28.05.2020 15.48, skrev Emil Velikov:
> Hi all,
> 
> I realise this has landed, so a small FYI comment.
> 
> On Sat, 9 May 2020 at 15:16, Noralf Trønnes <noralf@tronnes.org> wrote:
> 
>> +int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect)
>> +{
>> +       if (!buffer || !buffer->fb || !buffer->fb->funcs->dirty)
> 
> Hmm cannot think of a good reason why anyone would call this with
> !buffer || !buffer->fb?
> Might be a good idea to WARN in those cases - otherwise the user is
> given false sense to security.
> 

I agree, I'll send a fixup when I get through my backlog.

Noralf.

> Looking at the upcoming user (drm/gud) it already has both - so it's
> perfectly safe.
> 
> -Emil
> 
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