[PATCH v4 5/6] drm/i915/dp_link_training: Set all downstream MST ports to BAD before retrying

[Gil Dekel]

Before sending a uevent to userspace in order to trigger a corrective
modeset, we change the failing connector's link-status to BAD. However,
the downstream MST branch ports are left in their original GOOD state.

This patch utilizes the drm helper function
drm_dp_set_mst_topology_link_status() to rectify this and set all
downstream MST connectors' link-status to BAD before emitting the uevent
to userspace.

Signed-off-by: Gil Dekel <gildekel at chromium.org>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 42353b1ac487..e8b10f59e141 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -5995,16 +5995,20 @@ static void intel_dp_modeset_retry_work_fn(struct work_struct *work)
 	struct intel_dp *intel_dp =
 		container_of(work, typeof(*intel_dp), modeset_retry_work);
 	struct drm_connector *connector = &intel_dp->attached_connector->base;
-	drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s]\n", connector->base.id,
-		    connector->name);

-	/* Grab the locks before changing connector property*/
-	mutex_lock(&connector->dev->mode_config.mutex);
-	/* Set connector link status to BAD and send a Uevent to notify
-	 * userspace to do a modeset.
+	/* Set the connector's (and possibly all its downstream MST ports') link
+	 * status to BAD.
 	 */
+	mutex_lock(&connector->dev->mode_config.mutex);
+	drm_dbg_kms(connector->dev, "[CONNECTOR:%d:%s] link status %d -> %d\n",
+		    connector->base.id, connector->name,
+		    connector->state->link_status, DRM_MODE_LINK_STATUS_BAD);
 	drm_connector_set_link_status_property(connector,
 					       DRM_MODE_LINK_STATUS_BAD);
+	if (intel_dp->is_mst) {
+		drm_dp_set_mst_topology_link_status(&intel_dp->mst_mgr,
+						    DRM_MODE_LINK_STATUS_BAD);
+	}
 	mutex_unlock(&connector->dev->mode_config.mutex);
 	/* Send Hotplug uevent so userspace can reprobe */
 	drm_kms_helper_connector_hotplug_event(connector);
--
Gil Dekel, Software Engineer, Google / ChromeOS Display and Graphics