diff options
Diffstat (limited to 'drivers/usb/host/ehci-q.c')
| -rw-r--r-- | drivers/usb/host/ehci-q.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c index bd7ffe00fb62..aaf48c5d633f 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; @@ -1083,6 +1089,18 @@ 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); } } |