Automatically merging tracking-igloo_kernel-other into merging-stable-linaro-ux500-3.1stable-linaro-ux500-3.1

Conflicting files:

1 files changed, 18 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index 0917e3a3246..b7f9496e4f0 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -995,6 +995,12 @@ static void qh_link_async (struct ehci_hcd *ehci, struct ehci_qh *qh)
 	head->qh_next.qh = qh;
 	head->hw->hw_next = dma;
 
+	/*
+	 * flush qh descriptor into memory immediately,
+	 * see comments in qh_append_tds.
+	 */
+	ehci_sync_mem();
+
 	qh_get(qh);
 	qh->xacterrs = 0;
 	qh->qh_state = QH_STATE_LINKED;
@@ -1082,6 +1088,18 @@ static struct ehci_qh *qh_append_tds (
 			wmb ();
 			dummy->hw_token = token;
 
+			/*
+			 * Writing to dma coherent buffer on ARM may
+			 * be delayed to reach memory, so HC may not see
+			 * hw_token of dummy qtd in time, which can cause
+			 * the qtd transaction to be executed very late,
+			 * and degrade performance a lot. ehci_sync_mem
+			 * is added to flush 'token' immediatelly into
+			 * memory, so that ehci can execute the transaction
+			 * ASAP.
+			 */
+			ehci_sync_mem();
+
 			urb->hcpriv = qh_get (qh);
 		}
 	}