xHCI 1.0: Force Stopped Event(FSE)

FSE shall occur on the TD natural boundary. The software ep_ring dequeue pointer
exceed the hardware ep_ring dequeue pointer in these cases of Table-3. As a
result, the event_trb(pointed by hardware dequeue pointer) of the FSE can't be
found in the current TD(pointed by software dequeue pointer). What should we do
is to figured out the FSE case and skip over it.

Signed-off-by: Alex He <[email protected]>
Signed-off-by: Sarah Sharp <[email protected]>

Author: Alex He

drivers/usb/host/xhci-ring.c

@@ -2063,6 +2063,20 @@ static int handle_tx_event(struct xhci_hcd *xhci,
 		/* Is this a TRB in the currently executing TD? */
 		event_seg = trb_in_td(ep_ring->deq_seg, ep_ring->dequeue,
 				td->last_trb, event_dma);
+
+		/*
+		 * Skip the Force Stopped Event. The event_trb(event_dma) of FSE
+		 * is not in the current TD pointed by ep_ring->dequeue because
+		 * that the hardware dequeue pointer still at the previous TRB
+		 * of the current TD. The previous TRB maybe a Link TD or the
+		 * last TRB of the previous TD. The command completion handle
+		 * will take care the rest.
+		 */
+		if (!event_seg && trb_comp_code == COMP_STOP_INVAL) {
+			ret = 0;
+			goto cleanup;
+		}
+
 		if (!event_seg) {
 			if (!ep->skip ||
 			    !usb_endpoint_xfer_isoc(&td->urb->ep->desc)) {