xhci: Find out where an endpoint or stream stopped from its context.

When xHC is asked to stop an endpoint it will save the position it
stopped on in the endpoint or stream context.

xhci driver needs to know if the controller stopped on the exact same
TRB that the driver was asked to cancel as it then needs to move past
the TD instead of turning the TD to no-op TRBs.

xhci driver used to get the stopped position from a "stopped" transfer
event before the stop endpoint command completed, but if the ring
is already stopped, or in a halted or error state this event is missing.

Get the stopped position from the endpoint or stream context instead
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -691,7 +691,7 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
 	struct xhci_td *last_unlinked_td;
 	struct xhci_ep_ctx *ep_ctx;
 	struct xhci_virt_device *vdev;
-
+	u64 hw_deq;
 	struct xhci_dequeue_state deq_state;
 
 	if (unlikely(TRB_TO_SUSPEND_PORT(le32_to_cpu(trb->generic.field[3])))) {
@@ -752,12 +752,19 @@ static void xhci_handle_cmd_stop_ep(struct xhci_hcd *xhci, int slot_id,
 		 * If we stopped on the TD we need to cancel, then we have to
 		 * move the xHC endpoint ring dequeue pointer past this TD.
 		 */
-		if (cur_td == ep->stopped_td)
+		hw_deq = xhci_get_hw_deq(xhci, vdev, ep_index,
+					 cur_td->urb->stream_id);
+		hw_deq &= ~0xf;
+
+		if (trb_in_td(xhci, cur_td->start_seg, cur_td->first_trb,
+			      cur_td->last_trb, hw_deq, false)) {
 			xhci_find_new_dequeue_state(xhci, slot_id, ep_index,
-					cur_td->urb->stream_id,
-					cur_td, &deq_state);
-		else
+						    cur_td->urb->stream_id,
+						    cur_td, &deq_state);
+		} else {
 			td_to_noop(xhci, ep_ring, cur_td, false);
+		}
+
 remove_finished_td:
 		/*
 		 * The event handler won't see a completion for this TD anymore,