drm/i915/dp: Return min bpc supported by source instead of 0

Currently, intel_dp_dsc_max_src_input_bpc can return 0 for platforms not
supporting DSC, which could theoretically cause issues in clamp()
due to a low limit being greater than the high limit.

Instead, return the minimum bpc supported by the source to prevent
such issues.

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/all/CA+G9fYtNfM399_=_ff81zeRJv=0+z7oFJfPGmJgTp6yrJmU+1w@mail.gmail.com/
Fixes: 160672b86b0d ("drm/i915/dp: Use clamp for pipe_bpp limits with DSC")
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Tested-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250131041342.3086716-1-ankit.k.nautiyal@intel.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
(cherry picked from commit a67221b5eb8d59fb7e1f0df3ef9945b6a0f32cca)
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 bfc16fd25d22f5ae31ef9d4b5e9331171b3c76aa..be07034bfcc696693401b642ca2601b588bec739 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1791,7 +1791,7 @@ int intel_dp_dsc_max_src_input_bpc(struct intel_display *display)
        if (DISPLAY_VER(display) == 11)
                return 10;
 
-       return 0;
+       return intel_dp_dsc_min_src_input_bpc();
 }
 
 int intel_dp_dsc_compute_max_bpp(const struct intel_connector *connector,