xhci: Don't show incorrect WARN message about events for empty rings

commit e4ec40ec4b260efcca15089de4285a0a3411259b upstream.

xHC can generate two events for a short transfer if the short TRB and
last TRB in the TD are not the same TRB.

The driver will handle the TD after the first short event, and remove
it from its internal list. Driver then incorrectly prints a warning
for the second event:

"WARN Event TRB for slot x ep y with no TDs queued"

Fix this by not printing a warning if we get a event on a empty list
if the previous event was a short event.

Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index 82c746e2d85c0f7148cf780d9614eba3654f303d..353520005c135840ff94e12e002980e9ec4c326f 100644 (file)
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -2486,12 +2486,16 @@ static int handle_tx_event(struct xhci_hcd *xhci,
                 */
                if (list_empty(&ep_ring->td_list)) {
                        /*
-                        * A stopped endpoint may generate an extra completion
-                        * event if the device was suspended.  Don't print
-                        * warnings.
+                        * Don't print wanings if it's due to a stopped endpoint
+                        * generating an extra completion event if the device
+                        * was suspended. Or, a event for the last TRB of a
+                        * short TD we already got a short event for.
+                        * The short TD is already removed from the TD list.
                         */
+
                        if (!(trb_comp_code == COMP_STOPPED ||
-                               trb_comp_code == COMP_STOPPED_LENGTH_INVALID)) {
+                             trb_comp_code == COMP_STOPPED_LENGTH_INVALID ||
+                             ep_ring->last_td_was_short)) {
                                xhci_warn(xhci, "WARN Event TRB for slot %d ep %d with no TDs queued?\n",
                                                TRB_TO_SLOT_ID(le32_to_cpu(event->flags)),
                                                ep_index);