drm/dp/mst: change MST detection scheme

1. Get edid for all connected MST displays, not only on logical ports,
   in the same thread as MST topology detection is done:
     There are displays that have branches inside w/o logical ports.
     So in case another SST display connected downstream system can
     end-up in situation when 3 DOWN requests sent: two for
    ‘remote i2c read’ and one for ‘enum path resources’, making slots full.

2. Call notification callback in one place in the end of topology discovery/update:
     This is done to reduce number of events sent to userspace in case complex
     topology discovery is going, adding multiple number of connectors;

3. Remove notification callback call from short pulse interrupt processing function:
     This is done in order not to block interrupt processing function, in case any
     MST request will be made from it. Notification will be send from topology
     discovery/update work item.

Signed-off-by: Mykola Lysenko <Mykola.Lysenko@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Cc: stable@vger.kernel.org
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -1130,13 +1130,11 @@ static void drm_dp_add_port(struct drm_dp_mst_branch *mstb,
 			drm_dp_put_port(port);
 			goto out;
 		}
-		if (port->port_num >= DP_MST_LOGICAL_PORT_0) {
-			port->cached_edid = drm_get_edid(port->connector, &port->aux.ddc);
-			drm_mode_connector_set_tile_property(port->connector);
-		}
+
+		drm_mode_connector_set_tile_property(port->connector);
+
 		(*mstb->mgr->cbs->register_connector)(port->connector);
 	}
-
 out:
 	/* put reference to this port */
 	drm_dp_put_port(port);
@@ -1161,9 +1159,9 @@ static void drm_dp_update_port(struct drm_dp_mst_branch *mstb,
 	port->ddps = conn_stat->displayport_device_plug_status;
 
 	if (old_ddps != port->ddps) {
+		dowork = true;
 		if (port->ddps) {
 			drm_dp_check_port_guid(mstb, port);
-			dowork = true;
 		} else {
 			port->guid_valid = false;
 			port->available_pbn = 0;
@@ -1271,8 +1269,13 @@ static void drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *m
 		if (port->input)
 			continue;
 
-		if (!port->ddps)
+		if (!port->ddps) {
+			if (port->cached_edid) {
+				kfree(port->cached_edid);
+				port->cached_edid = NULL;
+			}
 			continue;
+		}
 
 		if (!port->available_pbn)
 			drm_dp_send_enum_path_resources(mgr, mstb, port);
@@ -1283,6 +1286,12 @@ static void drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *m
 				drm_dp_check_and_send_link_address(mgr, mstb_child);
 				drm_dp_put_mst_branch_device(mstb_child);
 			}
+		} else if (port->pdt == DP_PEER_DEVICE_SST_SINK ||
+			port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV) {
+			if (!port->cached_edid) {
+				port->cached_edid =
+					drm_get_edid(port->connector, &port->aux.ddc);
+			}
 		}
 	}
 }
@@ -1302,6 +1311,8 @@ static void drm_dp_mst_link_probe_work(struct work_struct *work)
 		drm_dp_check_and_send_link_address(mgr, mstb);
 		drm_dp_put_mst_branch_device(mstb);
 	}
+
+	(*mgr->cbs->hotplug)(mgr);
 }
 
 static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
@@ -1558,7 +1569,6 @@ static void drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
 			for (i = 0; i < txmsg->reply.u.link_addr.nports; i++) {
 				drm_dp_add_port(mstb, mgr->dev, &txmsg->reply.u.link_addr.ports[i]);
 			}
-			(*mgr->cbs->hotplug)(mgr);
 		}
 	} else {
 		mstb->link_address_sent = false;
@@ -2232,8 +2242,6 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
 
 			drm_dp_update_port(mstb, &msg.u.conn_stat);
 			DRM_DEBUG_KMS("Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n", msg.u.conn_stat.port_number, msg.u.conn_stat.legacy_device_plug_status, msg.u.conn_stat.displayport_device_plug_status, msg.u.conn_stat.message_capability_status, msg.u.conn_stat.input_port, msg.u.conn_stat.peer_device_type);
-			(*mgr->cbs->hotplug)(mgr);
-
 		} else if (msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
 			drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, msg.req_type, seqno, false);
 			if (!mstb)
@@ -2320,10 +2328,6 @@ enum drm_connector_status drm_dp_mst_detect_port(struct drm_connector *connector
 
 	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)
@@ -2378,10 +2382,7 @@ struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_
 
 	if (port->cached_edid)
 		edid = drm_edid_duplicate(port->cached_edid);
-	else {
-		edid = drm_get_edid(connector, &port->aux.ddc);
-		drm_mode_connector_set_tile_property(connector);
-	}
+
 	port->has_audio = drm_detect_monitor_audio(edid);
 	drm_dp_put_port(port);
 	return edid;