[PATCH 0/2] Better support for complex pixel formats

[Louis Chauvet <louis.chauvet@bootlin.com>]

This patchset aims to solve issues I found in [1], and at the same time 
simplify the composition algorithm.

I sent more igt-gpu-tools test [2] to cover more things and detect the 
issues in [1].

This patchset is based on [1].

Patch 1/2: This patch is a no-op, but make the code more readable 
regarding the pixel_read functions.

Patch 2/2: This patch is more complex. My main target was to solve issues 
I found in [1], but as it was very complex to do it "in place", I choose 
to rework the composition function.
The main two advantages are:
- It's now possible to create conversion function for packed & grouped 
pixels. Some pixel formats need absolute x/y position and not only an 
offset in the buffer to extract the correct value. This part also solve 
the issues I found in [1].
- The rotation management is now way easier to understand, there is no 
more switch case in different places and instead of copy/pasting rotation 
formula I used drm_rect_* helpers.

[1]: https://lore.kernel.org/dri-devel/20240110-vkms-yuv-v2-0-952fcaa5a193@riseup.net/
[2]: https://lore.kernel.org/igt-dev/20240201-kms_tests-v1-0-bc34c5d28b3f@bootlin.com/T/#t

Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>
---
Louis Chauvet (2):
      drm/vkms: Create a type to check a function pointer validity
      drm/vkms: Use a simpler composition function

 drivers/gpu/drm/vkms/vkms_composer.c |  97 ++++++++-----
 drivers/gpu/drm/vkms/vkms_drv.h      |  32 ++++-
 drivers/gpu/drm/vkms/vkms_formats.c  | 254 ++++++++++++++++++-----------------
 drivers/gpu/drm/vkms/vkms_formats.h  |   2 +-
 drivers/gpu/drm/vkms/vkms_plane.c    |  13 +-
 5 files changed, 236 insertions(+), 162 deletions(-)
---
base-commit: 5d189d57bb335a87ec38ea26fe43a5f3ed31ced7
change-id: 20240201-yuv-1337d90d9576

Best regards,
-- 
Louis Chauvet <louis.chauvet@bootlin.com>