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patch "usb: xhci: Reset halted endpoint if trb is noop" added to usb-linus

PATCH [email protected] 1 participant 1 message Oct 17, 2017

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Stable branch USB USB xHCI driver
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This is a note to let you know that I've just added the patch titled

usb: xhci: Reset halted endpoint if trb is noop

to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

Quoted 1 line

From 810a624bd1b64b13ddcc2eb5c1880526a750a870 Mon Sep 17 00:00:00 2001

From: Lu Baolu <[email protected]>
Date: Fri, 6 Oct 2017 17:45:29 +0300
Subject: usb: xhci: Reset halted endpoint if trb is noop

When a URB is cancled, xhci driver turns the untransferred trbs into no-ops. If an endpoint stalls on a no-op trb that belongs to the cancelled URB, the event handler won't reset the endpoint. Hence, it will stay halted.

Link http://marc.info/?l=linux-usb&m=149582598330127&w=2
Cc <[email protected]>
Signed-off-by Lu Baolu <[email protected]>
Signed-off-by Mathias Nyman <[email protected]>
Signed-off-by Greg Kroah-Hartman <[email protected]>
---
 drivers/usb/host/xhci-ring.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)
drivers/usb/host/xhci-ring.c +13 -7
index 48ae15afa59e..82c746e2d85c 100644
@@ -2580,15 +2580,21 @@ static int handle_tx_event(struct xhci_hcd *xhci,
 				(struct xhci_generic_trb *) ep_trb);
 
 		/*
-		 * No-op TRB should not trigger interrupts.
-		 * If ep_trb is a no-op TRB, it means the
-		 * corresponding TD has been cancelled. Just ignore
-		 * the TD.
+		 * No-op TRB could trigger interrupts in a case where
+		 * a URB was killed and a STALL_ERROR happens right
+		 * after the endpoint ring stopped. Reset the halted
+		 * endpoint. Otherwise, the endpoint remains stalled
+		 * indefinitely.
 		 */
 		if (trb_is_noop(ep_trb)) {
-			xhci_dbg(xhci,
-				 "ep_trb is a no-op TRB. Skip it for slot %u ep %u\n",
-				 slot_id, ep_index);
+			if (trb_comp_code == COMP_STALL_ERROR ||
+			    xhci_requires_manual_halt_cleanup(xhci, ep_ctx,
+							      trb_comp_code))
+				xhci_cleanup_halted_endpoint(xhci, slot_id,
+							     ep_index,
+							     ep_ring->stream_id,
+							     td, ep_trb,
+							     EP_HARD_RESET);
 			goto cleanup;
 		}
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2.14.2