Merge tag 'v4.18.20' into dev-4.18dev-4.18

This is the 4.18.20 stable release

Signed-off-by: Joel Stanley <joel@jms.id.au>

1 files changed, 37 insertions, 13 deletions

diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index 8e465095fe06..5d6517d37236 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -387,6 +387,22 @@ static bool intel_dp_link_params_valid(struct intel_dp *intel_dp, int link_rate,
 	return true;
 }
 
+static bool intel_dp_can_link_train_fallback_for_edp(struct intel_dp *intel_dp,
+						     int link_rate,
+						     uint8_t lane_count)
+{
+	const struct drm_display_mode *fixed_mode =
+		intel_dp->attached_connector->panel.fixed_mode;
+	int mode_rate, max_rate;
+
+	mode_rate = intel_dp_link_required(fixed_mode->clock, 18);
+	max_rate = intel_dp_max_data_rate(link_rate, lane_count);
+	if (mode_rate > max_rate)
+		return false;
+
+	return true;
+}
+
 int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
 					    int link_rate, uint8_t lane_count)
 {
@@ -396,9 +412,23 @@ int intel_dp_get_link_train_fallback_values(struct intel_dp *intel_dp,
 				    intel_dp->num_common_rates,
 				    link_rate);
 	if (index > 0) {
+		if (intel_dp_is_edp(intel_dp) &&
+		    !intel_dp_can_link_train_fallback_for_edp(intel_dp,
+							      intel_dp->common_rates[index - 1],
+							      lane_count)) {
+			DRM_DEBUG_KMS("Retrying Link training for eDP with same parameters\n");
+			return 0;
+		}
 		intel_dp->max_link_rate = intel_dp->common_rates[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,
+							      intel_dp_max_common_rate(intel_dp),
+							      lane_count >> 1)) {
+			DRM_DEBUG_KMS("Retrying Link training for eDP with same parameters\n");
+			return 0;
+		}
 		intel_dp->max_link_rate = intel_dp_max_common_rate(intel_dp);
 		intel_dp->max_link_lane_count = lane_count >> 1;
 	} else {
@@ -4842,19 +4872,13 @@ intel_dp_long_pulse(struct intel_connector *connector,
 		 */
 		status = connector_status_disconnected;
 		goto out;
-	} else {
-		/*
-		 * If display is now connected check links status,
-		 * there has been known issues of link loss triggering
-		 * long pulse.
-		 *
-		 * Some sinks (eg. ASUS PB287Q) seem to perform some
-		 * weird HPD ping pong during modesets. So we can apparently
-		 * end up with HPD going low during a modeset, and then
-		 * going back up soon after. And once that happens we must
-		 * retrain the link to get a picture. That's in case no
-		 * userspace component reacted to intermittent HPD dip.
-		 */
+	}
+
+	/*
+	 * Some external monitors do not signal loss of link synchronization
+	 * with an IRQ_HPD, so force a link status check.
+	 */
+	if (!intel_dp_is_edp(intel_dp)) {
 		struct intel_encoder *encoder = &dp_to_dig_port(intel_dp)->base;
 
 		intel_dp_retrain_link(encoder, ctx);