Hello Sean,
On 5/22/2026 1:09 AM, Sean Paul wrote:
From: Sean Paul <[email protected]>
Fix a typo in the loop condition in xelpd_program_plane_pre_csc_lut
for Segment 2 degamma programming, changing 'while (i++ > 130)' to
'while (i++ < 130)'. Also clamp Segment 2 to the last user-provided
LUT entry value instead of hardcoding it to 1.0 (1 << 24) to fix
a step discontinuity.
The commit message needs an update.
Is there an easy way to reproduce the problem you are seeing (e.g. IGT)?
I am wondering if we have to do the same on the pipe Gamma and Degamma.
==
Chaitanya
Link:
https://lore.kernel.org/intel-gfx/[email protected]/ #v1
Signed-off-by: Sean Paul <[email protected]>
Changes in v2:
- Split out into separate patches for pre/post csc fixes
- Dropped loop bounds fix in favor of [1]
[1]- https://lore.kernel.org/r/[email protected]
---
drivers/gpu/drm/i915/display/intel_color.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_color.c
b/drivers/gpu/drm/i915/display/intel_color.c
index 90d5dc2ef3e4..469011c83f9b 100644
--- a/drivers/gpu/drm/i915/display/intel_color.c
+++ b/drivers/gpu/drm/i915/display/intel_color.c
@@ -3953,6 +3953,7 @@ xelpd_program_plane_pre_csc_lut(struct intel_dsb *dsb,
enum plane_id plane = to_intel_plane(state->plane)->id;
const struct drm_color_lut32 *pre_csc_lut =
plane_state->hw.degamma_lut->data;
u32 i, lut_size;
+ u32 lut_val = 1 << 24;
if (icl_is_hdr_plane(display, plane)) {
lut_size = 128;
@@ -3963,7 +3964,7 @@ xelpd_program_plane_pre_csc_lut(struct intel_dsb *dsb,
if (pre_csc_lut) {
for (i = 0; i < lut_size; i++) {
- u32 lut_val =
drm_color_lut32_extract(pre_csc_lut[i].green, 24);
+ lut_val =
drm_color_lut32_extract(pre_csc_lut[i].green, 24);
intel_de_write_dsb(display, dsb,
PLANE_PRE_CSC_GAMC_DATA_ENH(pipe, plane, 0),
@@ -3975,7 +3976,7 @@ xelpd_program_plane_pre_csc_lut(struct intel_dsb *dsb,
do {
intel_de_write_dsb(display, dsb,
PLANE_PRE_CSC_GAMC_DATA_ENH(pipe, plane, 0),
- (1 << 24));
+ lut_val);
} while (i++ > 130);
} else {
for (i = 0; i < lut_size; i++) {
