From: Andiry Xu <andiry.xu@xxxxxxx>
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@xxxxxxxxxxxxxx>
Tested-by: Sander Eikelenboom <linux@xxxxxxxxxxxxxx>
Signed-off-by: Andiry Xu <andiry.xu@xxxxxxx>
Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
---
Greg, this bugfix should be queued for 2.6.36, assuming the isochronous
transfer patches are applied to that kernel.
drivers/usb/host/xhci-ring.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 2f19f3a..48e60d1 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -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);
}
--
1.6.3.3
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