[PATCH v2 0/7] Add YUV formats to VKMS

[Arthur Grillo]

This patchset aims to add support for additional buffer YUV formats.
More specifically, it adds support to:

Semi-planar formats:

- NV12
- NV16
- NV24
- NV21
- NV61
- NV42

Planar formats:

- YUV440
- YUV422
- YUV444
- YVU440
- YVU422
- YVU444

These formats have more than one plane, and most have chroma
subsampling. These properties don't have support on VKMS, so I had to
work on this before.

To ensure that the conversions from YUV to RGB are working, I wrote a
KUnit test. As the work from Harry on creating KUnit tests on VKMS[1] is
not yet merged, I took the setup part (Kconfig entry and .kunitfile)
from it.

Furthermore, I couldn't find any sources with the conversion matrices,
so I had to work out the values myself based on the ITU papers[2][3][4].
So, I'm not 100% sure if the values are accurate. I'd appreciate some
input if anyone has more knowledge in this area.

Also, I used two IGT tests to check if the formats were having a correct
conversion (all with the --extended flag):

- kms_plane@pixel_format
- kms_plane@pixel_format_source_clamping.

The nonsubsampled formats don't have support on IGT, so I sent a patch
fixing this[5].

Currently, this patchset does not add those formats to the writeback, as
it would require a rewrite of how the conversions are done (similar to
what was done on a previous patch[6]). So, I would like to review this
patchset before I start the work on this other part.

[1]: https://lore.kernel.org/all/20231108163647.106853-5-harry.wentland@xxxxxxx/
[2]: https://www.itu.int/rec/R-REC-BT.601-7-201103-I/en
[3]: https://www.itu.int/rec/R-REC-BT.709-6-201506-I/en
[4]: https://www.itu.int/rec/R-REC-BT.2020-2-201510-I/en
[5]: https://lists.freedesktop.org/archives/igt-dev/2024-January/066937.html
[6]: https://lore.kernel.org/dri-devel/20230414135151.75975-2-mcanal@xxxxxxxxxx/

Signed-off-by: Arthur Grillo <arthurgrillo@xxxxxxxxxx>
---
Changes in v2:
- Use EXPORT_SYMBOL_IF_KUNIT instead of including the .c test
  file (Maxime)
- Link to v1: https://lore.kernel.org/r/20240105-vkms-yuv-v1-0-34c4cd3455e0@xxxxxxxxxx

---
Arthur Grillo (7):
      drm/vkms: Use drm_frame directly
      drm/vkms: Add support for multy-planar framebuffers
      drm/vkms: Add range and encoding properties to pixel_read function
      drm/vkms: Add chroma subsampling
      drm/vkms: Add YUV support
      drm/vkms: Drop YUV formats TODO
      drm/vkms: Create KUnit tests for YUV conversions

 Documentation/gpu/vkms.rst                    |   3 +-
 drivers/gpu/drm/vkms/Kconfig                  |  15 ++
 drivers/gpu/drm/vkms/Makefile                 |   1 +
 drivers/gpu/drm/vkms/tests/.kunitconfig       |   4 +
 drivers/gpu/drm/vkms/tests/Makefile           |   3 +
 drivers/gpu/drm/vkms/tests/vkms_format_test.c | 156 ++++++++++++++++
 drivers/gpu/drm/vkms/vkms_drv.h               |   6 +-
 drivers/gpu/drm/vkms/vkms_formats.c           | 247 ++++++++++++++++++++++----
 drivers/gpu/drm/vkms/vkms_formats.h           |   9 +
 drivers/gpu/drm/vkms/vkms_plane.c             |  26 ++-
 drivers/gpu/drm/vkms/vkms_writeback.c         |   5 -
 11 files changed, 426 insertions(+), 49 deletions(-)
---
base-commit: eeb8e8d9f124f279e80ae679f4ba6e822ce4f95f
change-id: 20231226-vkms-yuv-6f7859f32df8

Best regards,
-- 
Arthur Grillo <arthurgrillo@xxxxxxxxxx>