We found that the external monitor would be failed to display
when hot-plug with dual Type-C USB cable on Dell WD19DC dock.
Due to the host would receive 2 lanes setting when the first HPD,
then receive 4 lanes setting later, but the host only sets 2 lanes
DP and skips to set 4 lanes DP. I modify DP lane count if the
current DP lane count is not the same as DPCD reading.
Signed-off-by: Ben Kao <ben.kao@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dp.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 5b3b6ae1e3d7..a9b9023c6744 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5545,6 +5545,12 @@ intel_dp_detect_dpcd(struct intel_dp *intel_dp)
if (!intel_dp_get_dpcd(intel_dp))
return connector_status_disconnected;
+ /* lanes count changed */
+ if (intel_dp->lane_count != drm_dp_max_lane_count(intel_dp->dpcd)) {
+ intel_dp->lane_count = drm_dp_max_lane_count(intel_dp->dpcd);
+ return connector_status_disconnected;
+ }
+
intel_dp->mst_detect = intel_dp_mst_detect(intel_dp);
/* if there's no downstream port, we're done */
--
2.17.1
