On 1/31/2025 6:19 PM, Jani Nikula wrote:
Commit 1c56e9a39833 ("drm/i915/dp: Get optimal link config to have best
compressed bpp") tries to find the best compressed bpp for the
link. However, it iterates from max to min bpp on display 13+, and from
min to max on other platforms. This presumably leads to minimum
compressed bpp always being chosen on display 11-12.
Iterate from high to low on all platforms to actually use the best
possible compressed bpp.
Fixes: 1c56e9a39833 ("drm/i915/dp: Get optimal link config to have best compressed bpp")
Cc: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v6.7+
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Thanks for the fix. I think I intended to iterate from max to min in
initial version of the patch (atleast the one sent to trybot [1]), but
some how messed it up while rebasing.
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@xxxxxxxxx>
[1]
https://lists.freedesktop.org/archives/intel-gfx-trybot/2022-June/129432.html
---
drivers/gpu/drm/i915/display/intel_dp.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index d1b4fd542a1f..ecf192262eb9 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2073,11 +2073,10 @@ icl_dsc_compute_link_config(struct intel_dp *intel_dp,
/* Compressed BPP should be less than the Input DSC bpp */
dsc_max_bpp = min(dsc_max_bpp, output_bpp - 1);
- for (i = 0; i < ARRAY_SIZE(valid_dsc_bpp); i++) {
- if (valid_dsc_bpp[i] < dsc_min_bpp)
+ for (i = ARRAY_SIZE(valid_dsc_bpp) - 1; i >= 0; i--) {
+ if (valid_dsc_bpp[i] < dsc_min_bpp ||
+ valid_dsc_bpp[i] > dsc_max_bpp)
continue;
- if (valid_dsc_bpp[i] > dsc_max_bpp)
- break;
ret = dsc_compute_link_config(intel_dp,
pipe_config,
