+static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper(
+ struct drm_dp_mst_branch *mstb,
+ uint8_t *guid)
+{
+ struct drm_dp_mst_branch *found_mstb;
+ struct drm_dp_mst_port *port;
+
+ 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)
+ return found_mstb;
+ }
+
+ return NULL;
+}
+
+static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device_by_guid(
+ struct drm_dp_mst_topology_mgr *mgr,
+ uint8_t *guid)
+{
+ struct drm_dp_mst_branch *mstb;
+
+ /* 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);
+
+ if (mstb)
+ kref_get(&mstb->kref);
+
+ mutex_unlock(&mgr->lock);
+ return mstb;
+}
+