Re: [PATCH 00/11] drm/vkms: improve color curve LUTs precision

[Leandro Ribeiro]

On 11/4/26 6:15 AM, Robert Mader wrote:
> Thanks a lot for the series!
> 
> I'm using it as part of a branch [1] to test my/our Weston post-blend
> color-op pipeline implementation [2] - including additional commits
> using the new script to add gamma 2.2 and 2.4 [3] curves. The Weston
> tests compare the vkms output against the GL renderer for e.g. NV12
> bt709-limited-range bt1886/gamma2.4 content - successfully (i.e. the
> results match very closely).
> 
> I also went through the commits and didn't spot any more issues. Thus
> with the 32bit issues raised by the bot addressed the whole series is:
> 
> Reviewed-by: Robert Mader <robert.mader@xxxxxxxxxxxxx>
> 
> Tested-by: Robert Mader <robert.mader@xxxxxxxxxxxxx>

Hello,

Thank you! I've pushed v2 today, fixing the main issue caught by Sashiko
bot (see "vkms: properly compute gamma LUT size in vkms_atomic_check()").

Also added your Reviewed-by and Tested-by tags.

Thanks,
Leandro

> 
> Best regards,
> 
> Robert
> 
> ---
> 
> 1: https://gitlab.com/rmader/linux/-/commits/post-blend-2026-11-02
> 
> 2: https://gitlab.freedesktop.org/wayland/weston/-/merge_requests/2157
> 
> 3: For SDR video, see https://gitlab.freedesktop.org/wayland/wayland-
> protocols/-/merge_requests/539
> 
> On 04.08.26 22:33, Leandro Ribeiro wrote:
>> 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 was 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.
>>
>> Leandro Ribeiro (11):
>>    drm/vkms: rename VKMS_LUT_SIZE to VKMS_GAMMA_LUT_SIZE
>>    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   |  561 +++++++
>>   drivers/gpu/drm/vkms/tests/vkms_color_test.c  |   46 +-
>>   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               |    2 +-
>>   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, 1383 insertions(+), 844 deletions(-)
>>   create mode 100644 drivers/gpu/drm/vkms/scripts/color-curve-lut.py
>>

-- 
Leandro Ribeiro