drm/amd/display: use halving distribution for all encode-to-linear curves

Browse source

In encode-to-linear conversions, LUT entries should be uniformly
distributed across the input range: non-linear encodings are already
approximately perceptually uniform, so every input code carries the same
weight. A fixed count per region does the opposite, concentrating
entries on the darker values and leaving few for the bright end, whereas
halving distribution spaces all 256 entries uniformly. This holds for
any encoded input, so remove the PQ/sRGB condition from commit
"drm/amd/display: use halving distribution for PQ/sRGB linearizing LUT"
and apply halving to all encode-to-linear operations
(pre-defined TF or user LUTs).

It fixes the following IGT kms_colorop subtests:
- plane-XR30-XR30-srgb_inv_eotf_lut-srgb_eotf_lut
- plane-XR30-XR30-gamma_2_2-gamma_2_2_inv-gamma_2_2

Fixes: a71d2b051f ("drm/amd/display: use halving distribution for PQ/sRGB linearizing LUT")
Reviewed-by: Alex Hung <alex.hung@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 6df7c9c307)

...

This commit is contained in:

Melissa Wen 2026-08-20 11:26:37 +02:00 • committed by Alex Deucher

parent 5a67d2e055

commit 4278d65a41

1 changed files with 10 additions and 24 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

34

drivers/gpu/drm/amd/display/dc/dcn30/dcn30_cm_common.c

View file