For DP2.0 as per the Spec on LT failure we need to reduce the lane count
if the lane count is not equal to 1. If lane count is 1 then need to
retry with reducing the link rate.
Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp.c | 20 ++++++++++++++++++--
1 file changed, 18 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 54ddc953e5bc..2b12ca45596d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -657,8 +657,20 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
"Retrying Link training for eDP with same parameters\n");
return 0;
}
- intel_dp->max_link_rate = intel_dp_common_rate(intel_dp, index - 1);
- intel_dp->max_link_lane_count = lane_count;
+ if (intel_dp->dpcd[DP_MAIN_LINK_CHANNEL_CODING] & DP_CAP_ANSI_128B132B) {
+ if (lane_count > 1) {
+ /* Reduce the lane count */
+ intel_dp->max_link_lane_count = lane_count >> 1;
+ intel_dp->max_link_rate = intel_dp_common_rate(intel_dp, index);
+ } else {
+ /* Reduce the link rate */
+ intel_dp->max_link_rate = intel_dp_common_rate(intel_dp, index - 1);
+ intel_dp->max_link_lane_count = intel_dp_max_common_lane_count(intel_dp);
+ }
+ } else {
+ intel_dp->max_link_rate = intel_dp_common_rate(intel_dp, index - 1);
+ intel_dp->max_link_lane_count = lane_count;
+ }
} else if (lane_count > 1) {
if (intel_dp_is_edp(intel_dp) &&
!intel_dp_can_link_train_fallback_for_edp(intel_dp,
@@ -675,6 +687,10 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
return -1;
}
+ drm_dbg_kms(&i915->drm,
+ "Retrying Link training with link rate %d and lane count %d\n",
+ intel_dp->max_link_rate, intel_dp->max_link_lane_count);
+
return 0;
}
--
2.25.1
