Commit 14184f9b authored Aug 09, 2010 by Andiry Xu Committed by Greg Kroah-Hartman Aug 23, 2010

USB: xHCI: update ring dequeue pointer when process missed tds



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>

parent a1669b2c

drivers/usb/host/xhci-ring.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -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);
		}