There are some unexpected banding and shimmer effects when using
steamOS/gamescope color pipeline for HDR on DCN32 or newer families.
Those problems are not present in Steam Deck (DCN301). It happens on
DCN32 because plane shaper LUT uses DCN30 CM3 helper to translate curves
instead of DCN10 CM helper. This series identifies the necessary changes
on CM3 helper to reduce differences on color transformation made by
those two helpers.
Patch 1 aims to solve the shimmer/colorful points that looks like a
wrong map of black values on red/green/blue colors. Patch 2 extends the
delta clamping fix made in commit 27fc10d1095f ("drm/amd/display: Fix
the delta clamping for shaper LUT") to solve some banding effects.
Banding is not fully solved by any helper and needs further
investigation.
One easy way to check the current and expected behavior is moving the
cursor (doing composition) to get the expected result from GFX. When the
cursor disappears, those color transformations are back to be done by
the display hw.
Lemme know your thoughts!
Melissa
Melissa Wen (2):
drm/amd/display: fix wrong color value mapping on DCN32 shaper LUT
drm/amd/display: extend delta clamping logic to CM3 LUT helper
.../amd/display/dc/dcn30/dcn30_cm_common.c | 32 +++++++++++++++----
.../display/dc/dwb/dcn30/dcn30_cm_common.h | 2 +-
.../amd/display/dc/hwss/dcn30/dcn30_hwseq.c | 9 +++---
.../amd/display/dc/hwss/dcn32/dcn32_hwseq.c | 17 ++++++----
.../amd/display/dc/hwss/dcn401/dcn401_hwseq.c | 16 ++++++----
5 files changed, 50 insertions(+), 26 deletions(-)
--
2.51.0
