[PATCH 1/4] usb: xhci: Fix TD invalidation on disconnected endpoints

[Michal Pecio <michal.pecio@gmail.com>]

This code prevents queuing Set TR Dequeue commands to endpoints of
disconnected devices. Turns out, USB core may "resuscitate" these
devices if a reset is requested before disconnection and completed
after reconnection, leading to reuse of the default endpoint.

Make sure that the default endpoint is cleaned up properly - TRBs
are erased (just in case, as usual) and Dequeue is set to Enqueue.
And don't overwrite TD_HALTED status, we may need it when resetting
of halted disconnected control endpoints is implemented later to
further prepare them for resuscitation.

Reported-by: Dennis Wissel <dennis@dsine.de>
Link: https://lore.kernel.org/linux-usb/SrQQcLIwRWyg9PdEIpc0eg@dsine.de/
Fixes: 7e0ef4332ed9 ("xhci: avoid xHC endpoint changes after disconnect or link error.")
Cc: stable@vger.kernel.org
Signed-off-by: Michal Pecio <michal.pecio@gmail.com>
---
 drivers/usb/host/xhci-ring.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index fa6684746305..7049787725fb 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -1061,12 +1061,6 @@ static int xhci_invalidate_cancelled_tds(struct xhci_hcd *xhci, struct xhci_virt
 			continue;
 		}
 
-		/* device disconnected or link error, ep will be dropped */
-		if (ep->ep_state & EP_DROP_PENDING) {
-			td->cancel_status = TD_CLEARED;
-			continue;
-		}
-
 		/*
 		 * If a ring stopped on the TD we need to cancel then we have to
 		 * move the xHC endpoint ring dequeue pointer past this TD.
@@ -1118,6 +1112,12 @@ static int xhci_invalidate_cancelled_tds(struct xhci_hcd *xhci, struct xhci_virt
 	if (!cached_td)
 		return 0;
 
+	/* Don't bother fixing disconnected endpoints except EP0 */
+	if (ep->ep_state & EP_DROP_PENDING && ep->ep_index != 0) {
+		cached_td->cancel_status = TD_CLEARED;
+		return 0;
+	}
+
 	err = xhci_move_deq_to_next_td(xhci, ep, cached_td->urb->stream_id);
 
 	if (err) {
-- 
2.48.1