USB: xHCI: update ring dequeue pointer when process missed tds
Andiry Xu [Mon, 9 Aug 2010 20:56:15 +0000 (13:56 -0700)]
This patch fixes a isoc transfer bug reported by Sander Eikelenboom.
When ep->skip is set, endpoint ring dequeue pointer should be updated
when processed every missed td. Although ring dequeue pointer will also
be updated when ep->skip is clear, leave it intact during missed tds
processing may cause two issues:

1). If the very next valid transfer following missed tds is a short
transfer, its actual_length will be miscalculated;
2). If there are too many missed tds during transfer, new inserted tds
may found the transfer ring full and urb enqueue fails.

Reported-by: Sander Eikelenboom <linux@eikelenboom.it>
Tested-by: Sander Eikelenboom <linux@eikelenboom.it>
Signed-off-by: Andiry Xu <andiry.xu@amd.com>
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-ring.c

index 2f19f3a..48e60d1 100644 (file)
@@ -1551,6 +1551,10 @@ static int process_isoc_td(struct xhci_hcd *xhci, struct xhci_td *td,
        /* calc actual length */
        if (ep->skip) {
                td->urb->iso_frame_desc[idx].actual_length = 0;
+               /* Update ring dequeue pointer */
+               while (ep_ring->dequeue != td->last_trb)
+                       inc_deq(xhci, ep_ring, false);
+               inc_deq(xhci, ep_ring, false);
                return finish_td(xhci, td, event_trb, event, ep, status, true);
        }