drm/amd/display: support up to 256 samples per region in degamma/blend LUT

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cm3_helper_translate_curve_to_degamma_hw_format() reads one tf_pts entry
per HW LUT point, limiting the number of samples per region to
NUMBER_SW_SEGMENTS (16, at seg_distr[k] = 4) - higher seg_distr[k]
underflows the increment to 0. But the next patch introduces a halving
distribution for PQ/sRGB EOTFs that requires up to 128 samples in its
upper region (seg_distr[k] = 7).

As preparation, extend the loop index by 4 bits and linearly interpolate
adjacent tf_pts entries with the new interp_tf_pts() helper, where the 4
least significant bits are weight in 1/16 increments. This raises the
cap to 256 samples per region (seg_distr[k] = 8). seg_distr[k] <= 4
paths remain unchanged: the 4 least significant bits remain zero and
interp_tf_pts() reduces to a direct lookup.

Tested-by: Matthew Schwartz <matthew.schwartz@linux.dev>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Co-developed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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Melissa Wen 2026-06-23 17:59:00 +02:00 • committed by Alex Deucher

parent 222e63bdda

commit 619e5b7e45

1 changed files with 25 additions and 7 deletions

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

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