---

yaml
---
r: 289685
b: refs/heads/master
c: 085deb1
h: refs/heads/master
i:
  289683: 41c7f03
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 2fdcd47b6980f4e26a97811a17f5be7cb919ef90
+refs/heads/master: 085deb16845ee0b25385274b39c70cc07e6e4140

trunk/drivers/usb/host/xhci-ring.c

@@ -249,16 +249,24 @@ static void inc_enq(struct xhci_hcd *xhci, struct xhci_ring *ring,
 }
 
 /*
- * Check to see if there's room to enqueue num_trbs on the ring.  See rules
- * above.
+ * Check to see if there's room to enqueue num_trbs on the ring and make sure
+ * enqueue pointer will not advance into dequeue segment. See rules above.
  */
 static inline int room_on_ring(struct xhci_hcd *xhci, struct xhci_ring *ring,
 		unsigned int num_trbs)
 {
-	if (ring->num_trbs_free >= num_trbs)
-		return 1;
+	int num_trbs_in_deq_seg;
 
-	return 0;
+	if (ring->num_trbs_free < num_trbs)
+		return 0;
+
+	if (ring->type != TYPE_COMMAND && ring->type != TYPE_EVENT) {
+		num_trbs_in_deq_seg = ring->dequeue - ring->deq_seg->trbs;
+		if (ring->num_trbs_free < num_trbs + num_trbs_in_deq_seg)
+			return 0;
+	}
+
+	return 1;
 }
 
 /* Ring the host controller doorbell after placing a command on the ring */
@@ -2529,13 +2537,6 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring,
 			return -ENOMEM;
 		}
 
-		if (ep_ring->enq_seg == ep_ring->deq_seg &&
-				ep_ring->dequeue > ep_ring->enqueue) {
-			xhci_err(xhci, "Can not expand the ring while dequeue "
-				"pointer has not passed the link TRB\n");
-			return -ENOMEM;
-		}
-
 		xhci_dbg(xhci, "ERROR no room on ep ring, "
 					"try ring expansion\n");
 		num_trbs_needed = num_trbs - ep_ring->num_trbs_free;