3 files changed, 21 insertions, 4 deletions

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 9798bb79fe59..0a9d3aad3cba 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -861,6 +861,8 @@ static void drm_dp_destroy_port(struct kref *kref)
         struct drm_dp_mst_topology_mgr *mgr = port->mgr;
         if (!port->input) {
                 port->vcpi.num_slots = 0;
+
+                kfree(port->cached_edid);
                 if (port->connector)
                         (*port->mgr->cbs->destroy_connector)(mgr, port->connector);
                 drm_dp_port_teardown_pdt(port, port->pdt);
@@ -1100,6 +1102,10 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
                 char proppath[255];
                 build_mst_prop_path(port, mstb, proppath, sizeof(proppath));
                 port->connector = (*mstb->mgr->cbs->add_connector)(mstb->mgr, port, proppath);
+
+                if (port->port_num >= 8) {
+                        port->cached_edid = drm_get_edid(port->connector, &port->aux.ddc);
+                }
         }
 
         /* put reference to this port */
@@ -2170,7 +2176,8 @@ EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
  * This returns the current connection state for a port. It validates the
  * port pointer still exists so the caller doesn't require a reference
  */
-enum drm_connector_status drm_dp_mst_detect_port(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
+enum drm_connector_status drm_dp_mst_detect_port(struct drm_connector *connector,
+                                                 struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
 {
         enum drm_connector_status status = connector_status_disconnected;
 
@@ -2189,6 +2196,10 @@ enum drm_connector_status drm_dp_mst_detect_port(struct drm_dp_mst_topology_mgr
 
         case DP_PEER_DEVICE_SST_SINK:
                 status = connector_status_connected;
+                /* for logical ports - cache the EDID */
+                if (port->port_num >= 8 && !port->cached_edid) {
+                        port->cached_edid = drm_get_edid(connector, &port->aux.ddc);
+                }
                 break;
         case DP_PEER_DEVICE_DP_LEGACY_CONV:
                 if (port->ldps)
@@ -2220,7 +2231,11 @@ struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_
         if (!port)
                 return NULL;
 
-        edid = drm_get_edid(connector, &port->aux.ddc);
+        if (port->cached_edid)
+                edid = drm_edid_duplicate(port->cached_edid);
+        else
+                edid = drm_get_edid(connector, &port->aux.ddc);
+
         drm_dp_put_port(port);
         return edid;
 }
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index bfe359506377..428bb3041621 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -283,7 +283,7 @@ intel_dp_mst_detect(struct drm_connector *connector, bool force)
         struct intel_connector *intel_connector = to_intel_connector(connector);
         struct intel_dp *intel_dp = intel_connector->mst_port;
 
-        return drm_dp_mst_detect_port(&intel_dp->mst_mgr, intel_connector->port);
+        return drm_dp_mst_detect_port(connector, &intel_dp->mst_mgr, intel_connector->port);
 }
 
 static int
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index cec6383bbdb8..00c1da927245 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -92,6 +92,8 @@ struct drm_dp_mst_port {
         struct drm_dp_vcpi vcpi;
         struct drm_connector *connector;
         struct drm_dp_mst_topology_mgr *mgr;
+
+        struct edid *cached_edid; /* for DP logical ports - make tiling work */
 };
 
 /**
@@ -474,7 +476,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
 int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled);
 
 
-enum drm_connector_status drm_dp_mst_detect_port(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
+enum drm_connector_status drm_dp_mst_detect_port(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);
 
 struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port);