[PATCH v2 0/2] drm/vkms: Fix bad matrix offset component multiplication

[Ariel D'Alessandro <ariel.dalessandro@collabora.com>]

This patch series fixes a bug in the 3x4 matrix multiplication for BT709
enconding/decoding, where the offset component if not handled properly.

Currently, BT.709 encoding matrix kunit tests don't cover the offset
component multiplication, so a new set of tests is added.

The bug was found while working on the IGT tools CRTC (post-blend) color
pipelines, see submitted patchset [0] (patch [1] in particular) for the
full context.

[0] https://lore.kernel.org/igt-dev/20251223-post-blend-colorops-v2-0-f40aca9795bd@collabora.com/
[1] https://lore.kernel.org/igt-dev/20251223-post-blend-colorops-v2-7-f40aca9795bd@collabora.com/

Signed-off-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
---
Changes in v2:
- Added kunit tests for alternative BT709 encoding matrix.
- Link to v1: https://lore.kernel.org/r/20251223-vkms-composer-fix-matrix-v1-1-10a979e06209@collabora.com

---
Ariel D'Alessandro (2):
      drm/vkms: Fix bad matrix offset component multiplication
      drm/vkms: Add kunit tests for alternative BT709 encoding matrix

 drivers/gpu/drm/vkms/tests/vkms_color_test.c | 146 +++++++++++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_composer.c         |  13 ++-
 2 files changed, 156 insertions(+), 3 deletions(-)
---
base-commit: b96bcfba104c65db41378a04f5ccac186f79578f
change-id: 20251223-vkms-composer-fix-matrix-aa2c593f4515

Best regards,
-- 
Ariel D'Alessandro <ariel.dalessandro@collabora.com>