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>

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index be07034bfcc696693401b642ca2601b588bec739..aa77ddcee42c8624012ea42a79f66f725fb6f6ce 100644 (file)
--- 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,