drm/i915/dp: Reset cached LTTPR count if number of LTTPRs is unsupported

After detection the cached LTTPR count can be checked to determine if
LTTPRs in non-transparent mode were detected. Reset the cached LTTPR
count if the reported number of LTTPRs is invalid to ensure the above
checks work as expected.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240708190029.271247-4-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_dp_link_training.c b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
index d044c8e36bb3d60551b76ab5220d8252ffe83849..56b9c5cb1254d9be76e8f091e4855512ca5b744c 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp_link_training.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_link_training.c
@@ -174,7 +174,7 @@ static int intel_dp_init_lttpr_phys(struct intel_dp *intel_dp, const u8 dpcd[DP_
         * still taking into account any LTTPR common lane- rate/count limits.
         */
        if (lttpr_count < 0)
-               return 0;
+               goto out_reset_lttpr_count;
 
        if (!intel_dp_set_lttpr_transparent_mode(intel_dp, false)) {
                lt_dbg(intel_dp, DP_PHY_DPRX,