[PATCH v2 00/12] drm/vkms: improve color curve LUTs precision

[Leandro Ribeiro]

Currently VKMS only supports uniform LUTs. Besides the userspace
provided LUTs, it also represents color curves with LUTs, as it can't
simply implement the continuous curve formulas (floating-point would be
required).

This adds support to represent color curves with non-uniform LUTs,
improving the precision significantly. It also provides a script
that can be used to create these LUTs.

The optimized LUTs use more samples in regions where the interpolation
and quantization errors are higher (usually in regions with a steeper
slope). The LUT generator script compares different strategies and uses
greedy subdivision, which outperformed the other methods, to generate
the optimized LUTs for VKMS.

For now, only the existing sRGB and inverse sRGB curves are replaced.
Support for more color curves will be added in future patchsets.

v2:
- Fixed a few minor issues spotted by Sashiko bot
- Added reviewed-by and tested-by tags
- Rebased

Leandro Ribeiro (12):
  drm/vkms: rename VKMS_LUT_SIZE to VKMS_GAMMA_LUT_SIZE
  vkms: properly compute gamma LUT size in vkms_atomic_check()
  drm/vkms: allow color curve LUTs to have different sizes
  drm/vkms: remove TEST_LUT_SIZE
  drm/vkms: remove linear_eotf
  drm/vkms: improve the way in which we access LUT member
  drm/vkms: rename struct vkms_color_lut::base to y
  drm/vkms: rename get_lut_index() to get_uniform_lut_index()
  drm/vkms: add support to non-uniform LUT for internal color curves
  drm/vkms: test sRGB and inverse sRGB LUTs using more samples
  drm/vkms: add script to create optimized LUTs for color curves
  drm/vkms: replace uniform sRGB LUT and its inverse with optimal ones

 .../gpu/drm/vkms/scripts/color-curve-lut.py   |  573 +++++++
 drivers/gpu/drm/vkms/tests/vkms_color_test.c  |   48 +-
 drivers/gpu/drm/vkms/vkms_composer.c          |  127 +-
 drivers/gpu/drm/vkms/vkms_composer.h          |    2 +-
 drivers/gpu/drm/vkms/vkms_crtc.c              |    4 +-
 drivers/gpu/drm/vkms/vkms_drv.c               |    4 +-
 drivers/gpu/drm/vkms/vkms_drv.h               |   13 +-
 drivers/gpu/drm/vkms/vkms_luts.c              | 1469 ++++++++---------
 drivers/gpu/drm/vkms/vkms_luts.h              |    3 -
 9 files changed, 1397 insertions(+), 846 deletions(-)
 create mode 100644 drivers/gpu/drm/vkms/scripts/color-curve-lut.py

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2.56.0