From 230b19bc2bcc5897d0e20b4ce7e9790a469a2db0 Mon Sep 17 00:00:00 2001
From: Jani Nikula <jani.nikula@intel.com>
Date: Fri, 31 Jan 2025 14:49:54 +0200
Subject: [PATCH] drm/i915/dp: Iterate DSC BPP from high to low on all
platforms
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@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: <stable@vger.kernel.org> # v6.7+
Reviewed-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/3bba67923cbcd13a59d26ef5fa4bb042b13c8a9b.1738327620.git.jani.nikula@intel.com
(cherry picked from commit 56b0337d429356c3b9ecc36a03023c8cc856b196)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
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 be07034bfcc6..aa77ddcee42c 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2072,11 +2072,10 @@ 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, pipe_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,