Patch "drm/dp/mst: move GUID storage from mgr, port to only mst branch" has been added to the 4.4-stable tree

@@ -1013,18 +1013,27 @@ static bool drm_dp_port_setup_pdt(struct
 	return send_link;
 }
 
-static void drm_dp_check_port_guid(struct drm_dp_mst_branch *mstb,
-				   struct drm_dp_mst_port *port)
+static void drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid)
 {
 	int ret;
-	if (port->dpcd_rev >= 0x12) {
-		port->guid_valid = drm_dp_validate_guid(mstb->mgr, port->guid);
-		if (!port->guid_valid) {
-			ret = drm_dp_send_dpcd_write(mstb->mgr,
-						     port,
-						     DP_GUID,
-						     16, port->guid);
-			port->guid_valid = true;
+
+	memcpy(mstb->guid, guid, 16);
+
+	if (!drm_dp_validate_guid(mstb->mgr, mstb->guid)) {
+		if (mstb->port_parent) {
+			ret = drm_dp_send_dpcd_write(
+					mstb->mgr,
+					mstb->port_parent,
+					DP_GUID,
+					16,
+					mstb->guid);
+		} else {
+
+			ret = drm_dp_dpcd_write(
+					mstb->mgr->aux,
+					DP_GUID,
+					mstb->guid,
+					16);
 		}
 	}
 }

@@ -1081,7 +1090,6 @@ static void drm_dp_add_port(struct drm_d
 	port->dpcd_rev = port_msg->dpcd_revision;
 	port->num_sdp_streams = port_msg->num_sdp_streams;
 	port->num_sdp_stream_sinks = port_msg->num_sdp_stream_sinks;
-	memcpy(port->guid, port_msg->peer_guid, 16);
 
 	/* manage mstb port lists with mgr lock - take a reference
 	   for this list */

@@ -1094,11 +1102,9 @@ static void drm_dp_add_port(struct drm_d
 
 	if (old_ddps != port->ddps) {
 		if (port->ddps) {
-			drm_dp_check_port_guid(mstb, port);
 			if (!port->input)
 				drm_dp_send_enum_path_resources(mstb->mgr, mstb, port);
 		} else {
-			port->guid_valid = false;
 			port->available_pbn = 0;
 			}
 	}

@@ -1157,10 +1163,8 @@ static void drm_dp_update_port(struct dr
 
 	if (old_ddps != port->ddps) {
 		if (port->ddps) {
-			drm_dp_check_port_guid(mstb, port);
 			dowork = true;
 		} else {
-			port->guid_valid = false;
 			port->available_pbn = 0;
 		}
 	}

@@ -1217,13 +1221,14 @@ static struct drm_dp_mst_branch *get_mst
 	struct drm_dp_mst_branch *found_mstb;
 	struct drm_dp_mst_port *port;
 
+	if (memcmp(mstb->guid, guid, 16) == 0)
+		return mstb;
+
+
 	list_for_each_entry(port, &mstb->ports, next) {
 		if (!port->mstb)
 			continue;
 
-		if (port->guid_valid && memcmp(port->guid, guid, 16) == 0)
-			return port->mstb;
-
 		found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid);
 
 		if (found_mstb)

@@ -1242,10 +1247,7 @@ static struct drm_dp_mst_branch *drm_dp_
 	/* find the port by iterating down */
 	mutex_lock(&mgr->lock);
 
-	if (mgr->guid_valid && memcmp(mgr->guid, guid, 16) == 0)
-		mstb = mgr->mst_primary;
-	else
-		mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
+	mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
 
 	if (mstb)
 		kref_get(&mstb->kref);

@@ -1550,6 +1552,9 @@ static void drm_dp_send_link_address(str
 				       txmsg->reply.u.link_addr.ports[i].num_sdp_streams,
 				       txmsg->reply.u.link_addr.ports[i].num_sdp_stream_sinks);
 			}
+
+			drm_dp_check_mstb_guid(mstb, txmsg->reply.u.link_addr.guid);
+
 			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]);
 			}

@@ -1984,20 +1989,6 @@ int drm_dp_mst_topology_mgr_set_mst(stru
 			goto out_unlock;
 		}
 
-
-		/* sort out guid */
-		ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, mgr->guid, 16);
-		if (ret != 16) {
-			DRM_DEBUG_KMS("failed to read DP GUID %d\n", ret);
-			goto out_unlock;
-		}
-
-		mgr->guid_valid = drm_dp_validate_guid(mgr, mgr->guid);
-		if (!mgr->guid_valid) {
-			ret = drm_dp_dpcd_write(mgr->aux, DP_GUID, mgr->guid, 16);
-			mgr->guid_valid = true;
-		}
-
 		queue_work(system_long_wq, &mgr->work);
 
 		ret = 0;

@@ -2219,6 +2210,7 @@ static int drm_dp_mst_handle_up_req(stru
 			}
 
 			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);
 

@@ -44,8 +44,6 @@ struct drm_dp_vcpi {
 /**
  * struct drm_dp_mst_port - MST port
  * @kref: reference count for this port.
- * @guid_valid: for DP 1.2 devices if we have validated the GUID.
- * @guid: guid for DP 1.2 device on this port.
  * @port_num: port number
  * @input: if this port is an input port.
  * @mcs: message capability status - DP 1.2 spec.

@@ -70,10 +68,6 @@ struct drm_dp_vcpi {
 struct drm_dp_mst_port {
 	struct kref kref;
 
-	/* if dpcd 1.2 device is on this port - its GUID info */
-	bool guid_valid;
-	u8 guid[16];
-
 	u8 port_num;
 	bool input;
 	bool mcs;

@@ -109,10 +103,12 @@ struct drm_dp_mst_port {
  * @tx_slots: transmission slots for this device.
  * @last_seqno: last sequence number used to talk to this.
  * @link_address_sent: if a link address message has been sent to this device yet.
+ * @guid: guid for DP 1.2 branch device. port under this branch can be
+ * identified by port #.
  *
  * This structure represents an MST branch device, there is one
- * primary branch device at the root, along with any others connected
- * to downstream ports
+ * primary branch device at the root, along with any other branches connected
+ * to downstream port of parent branches.
  */
 struct drm_dp_mst_branch {
 	struct kref kref;

@@ -131,6 +127,9 @@ struct drm_dp_mst_branch {
 	struct drm_dp_sideband_msg_tx *tx_slots[2];
 	int last_seqno;
 	bool link_address_sent;
+
+	/* global unique identifier to identify branch devices */
+	u8 guid[16];
 };
 
 

@@ -405,11 +404,9 @@ struct drm_dp_payload {
  * @conn_base_id: DRM connector ID this mgr is connected to.
  * @down_rep_recv: msg receiver state for down replies.
  * @up_req_recv: msg receiver state for up requests.
- * @lock: protects mst state, primary, guid, dpcd.
+ * @lock: protects mst state, primary, dpcd.
  * @mst_state: if this manager is enabled for an MST capable port.
  * @mst_primary: pointer to the primary branch device.
- * @guid_valid: GUID valid for the primary branch device.
- * @guid: GUID for primary port.
  * @dpcd: cache of DPCD for primary port.
  * @pbn_div: PBN to slots divisor.
  *

@@ -431,13 +428,11 @@ struct drm_dp_mst_topology_mgr {
 	struct drm_dp_sideband_msg_rx up_req_recv;
 
 	/* pointer to info about the initial MST device */
-	struct mutex lock; /* protects mst_state + primary + guid + dpcd */
+	struct mutex lock; /* protects mst_state + primary + dpcd */
 
 	bool mst_state;
 	struct drm_dp_mst_branch *mst_primary;
-	/* primary MST device GUID */
-	bool guid_valid;
-	u8 guid[16];
+
 	u8 dpcd[DP_RECEIVER_CAP_SIZE];
 	u8 sink_count;
 	int pbn_div;