Re: xhci: WARN Set TR Deq Ptr cmd failed due to incorrect slot or ep state.

Mathias Nyman
2025-04-07T07:14:21Z

On 6.4.2025 5.40, Alan Stern wrote:
> On Sun, Apr 06, 2025 at 12:23:11AM +0200, Michał Pecio wrote:
>> Looks like some URB stalled and usb_storage reset the device without
>> usb_clear_halt(). Then the core didn't usb_hcd_reset_endpoint() either.
>> And apparently EP_STALLED is still set in xhci_hcd after all that time.
>>
>> Then usb_storage submits one URB which never executes because the EP
>> is in Running-Idle state and the doorbell is inhibited by EP_STALLED.
>> 30s later it times out, unlinks the URB and resets again. Set TR Deq
>> fails because the endpoint is Running.
>
>> Not sure if it's a USB core bug or something that xHCI should take
>> care of on its own. For now, reverting those two "stall" patches ought
>> to clean up the noise.
>
> The core believes that resetting a device should erase the endpoint
> information in the HCD. There is a callback in hub_port_reset() to that
> effect:
>
> if (hcd->driver->reset_device)
> hcd->driver->reset_device(hcd, udev);
>
> So after this the EP should not be in the Running-Idle state; in fact it
> should not exist at all (unless it is ep0, but in this case I think it
> isn't).
>

> Is the implementation of the reset_device callback in xhci-hcd missing
> something?
>
> Alan Stern

Thanks, I believe this is at least part of the issue here, thanks for the tip.

We don't clear the virt_dev->eps[ep_index].ep_state flags after device reset.

And the two new patches Michal pointed out rely even more of ep_state flags than
before, causing a regression.

0c74d232578b xhci: Avoid queuing redundant Stop Endpoint command for stalled endpoint
860f5d0d3594 xhci: Prevent early endpoint restart when handling STALL errors.

Does this oneliner help?

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 0452b8d65832..044c70c17746 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -3930,6 +3930,7 @@ static int xhci_discover_or_reset_device(struct usb_hcd *hcd,
&virt_dev->eps[i],
virt_dev->tt_info);
xhci_clear_endpoint_bw_info(&virt_dev->eps[i].bw_info);
+ ep->ep_state = 0;
}
/* If necessary, update the number of active TTs on this root port */
xhci_update_tt_active_eps(xhci, virt_dev, old_active_eps);

Thanks
Mathias