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[PATCH 4.2.y-ckt 009/211] xhci: don't finish a TD if we get a short transfer event mid TD

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4.2.8-ckt1 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Mathias Nyman <mathias.nyman@linux.intel.com>

commit e210c422b6fdd2dc123bedc588f399aefd8bf9de upstream.

If the difference is big enough between the bytes asked and received
in a bulk transfer we can get a short transfer event pointing to a TRB in
the middle of the TD. We don't want to handle the TD yet as we will anyway
receive a new event for the last TRB in the TD.

Hold off from finishing the TD and removing it from the list until we
receive an event for the last TRB in the TD

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ kamal: backport to 4.2-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/usb/host/xhci-ring.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 63041c1..d08d1f1 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2156,6 +2156,10 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)));
 	/* Fast path - was this the last TRB in the TD for this URB? */
 	if (event_trb == td->last_trb) {
+		if (td->urb_length_set && trb_comp_code == COMP_SHORT_TX)
+			return finish_td(xhci, td, event_trb, event, ep,
+					 status, false);
+
 		if (EVENT_TRB_LEN(le32_to_cpu(event->transfer_len)) != 0) {
 			td->urb->actual_length =
 				td->urb->transfer_buffer_length -
@@ -2207,6 +2211,12 @@ static int process_bulk_intr_td(struct xhci_hcd *xhci, struct xhci_td *td,
 			td->urb->actual_length +=
 				TRB_LEN(le32_to_cpu(cur_trb->generic.field[2])) -
 				EVENT_TRB_LEN(le32_to_cpu(event->transfer_len));
+
+		if (trb_comp_code == COMP_SHORT_TX) {
+			xhci_dbg(xhci, "mid bulk/intr SP, wait for last TRB event\n");
+			td->urb_length_set = true;
+			return 0;
+		}
 	}
 
 	return finish_td(xhci, td, event_trb, event, ep, status, false);
-- 
1.9.1

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[PATCH 4.2.y-ckt 009/211] xhci: don't finish a TD if we get a short transfer event mid TD Kamal Mostafa <kamal@canonical.com> - 2016-01-05 20:50 +0100
  Re: [PATCH 4.2.y-ckt 009/211] xhci: don't finish a TD if we get a  short transfer event mid TD Ben Hutchings <ben@decadent.org.uk> - 2016-01-06 18:10 +0100
    Re: [PATCH 4.2.y-ckt 009/211] xhci: don't finish a TD if we get a  short transfer event mid TD Kamal Mostafa <kamal@canonical.com> - 2016-01-06 21:00 +0100
      Re: [PATCH 4.2.y-ckt 009/211] xhci: don't finish a TD if we get a  short transfer event mid TD Ben Hutchings <ben@decadent.org.uk> - 2016-01-07 04:00 +0100

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