Patch "drm/dp/mst: always send reply for UP request" has been added to the 4.4-stable tree

@@ -1489,26 +1489,18 @@ static void process_single_down_tx_qlock
 }
 
 /* called holding qlock */
-static void process_single_up_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
+static void process_single_up_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
+				       struct drm_dp_sideband_msg_tx *txmsg)
 {
-	struct drm_dp_sideband_msg_tx *txmsg;
 	int ret;
 
 	/* construct a chunk from the first msg in the tx_msg queue */
-	if (list_empty(&mgr->tx_msg_upq)) {
-		mgr->tx_up_in_progress = false;
-		return;
-	}
-
-	txmsg = list_first_entry(&mgr->tx_msg_upq, struct drm_dp_sideband_msg_tx, next);
 	ret = process_single_tx_qlock(mgr, txmsg, true);
-	if (ret == 1) {
-		/* up txmsgs aren't put in slots - so free after we send it */
-		list_del(&txmsg->next);
-		kfree(txmsg);
-	} else if (ret)
+
+	if (ret != 1)
 		DRM_DEBUG_KMS("failed to send msg in q %d\n", ret);
-	mgr->tx_up_in_progress = true;
+
+	txmsg->dst->tx_slots[txmsg->seqno] = NULL;
 }
 
 static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,

@@ -1895,11 +1887,12 @@ static int drm_dp_send_up_ack_reply(stru
 	drm_dp_encode_up_ack_reply(txmsg, req_type);
 
 	mutex_lock(&mgr->qlock);
-	list_add_tail(&txmsg->next, &mgr->tx_msg_upq);
-	if (!mgr->tx_up_in_progress) {
-		process_single_up_tx_qlock(mgr);
-	}
+
+	process_single_up_tx_qlock(mgr, txmsg);
+
 	mutex_unlock(&mgr->qlock);
+
+	kfree(txmsg);
 	return 0;
 }
 

@@ -2809,7 +2802,6 @@ int drm_dp_mst_topology_mgr_init(struct
 	mutex_init(&mgr->qlock);
 	mutex_init(&mgr->payload_lock);
 	mutex_init(&mgr->destroy_connector_lock);
-	INIT_LIST_HEAD(&mgr->tx_msg_upq);
 	INIT_LIST_HEAD(&mgr->tx_msg_downq);
 	INIT_LIST_HEAD(&mgr->destroy_connector_list);
 	INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);

@@ -450,9 +450,7 @@ struct drm_dp_mst_topology_mgr {
 	   the mstb tx_slots and txmsg->state once they are queued */
 	struct mutex qlock;
 	struct list_head tx_msg_downq;
-	struct list_head tx_msg_upq;
 	bool tx_down_in_progress;
-	bool tx_up_in_progress;
 
 	/* payload info + lock for it */
 	struct mutex payload_lock;