This ports U-Boot commit d5daa02d8d9e7c403a3339db1966e8413e64e408:
| Author: Stefan Agner <stefan@xxxxxxxx>
| AuthorDate: Mon Sep 27 14:42:58 2021 +0200
|
| usb: xhci: reset endpoint on USB stall
|
| There are devices which cause a USB stall when trying to read strings.
| Specifically Arduino Mega R3 stalls when trying to read the product
| string.
|
| The stall currently remains unhandled, and subsequent retries submit new
| transfers on a stopped endpoint which ultimately cause a crash in
| abort_td():
| WARN halted endpoint, queueing URB anyway.
| XHCI control transfer timed out, aborting...
| Unexpected XHCI event TRB, skipping... (3affe040 00000000 13000000 02008401)
| BUG at drivers/usb/host/xhci-ring.c:505/abort_td()!
| BUG!
| resetting ...
|
| Linux seems to be able to recover from the stall by issuing a
| TRB_RESET_EP command.
|
| Introduce reset_ep() which issues a TRB_RESET_EP followed by setting the
| transfer ring dequeue pointer via TRB_SET_DEQ. This allows to properly
| recover from a USB stall error and continue communicating with the USB
| device.
|
| Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
---
drivers/usb/host/xhci-ring.c | 40 ++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
index c645285da7fc..056613445330 100644
--- a/drivers/usb/host/xhci-ring.c
+++ b/drivers/usb/host/xhci-ring.c
@@ -500,6 +500,42 @@ union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected,
BUG();
}
+/*
+ * Send reset endpoint command for given endpoint. This recovers from a
+ * halted endpoint (e.g. due to a stall error).
+ */
+static void reset_ep(struct usb_device *udev, int ep_index, unsigned int timeout_ms)
+{
+ struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
+ struct xhci_ring *ring = ctrl->devs[udev->slot_id]->eps[ep_index].ring;
+ union xhci_trb *event;
+ u64 addr;
+ u32 field;
+
+ dev_info(&udev->dev, "Resetting EP %d...\n", ep_index);
+
+ xhci_queue_command(ctrl, 0, udev->slot_id, ep_index, TRB_RESET_EP);
+ event = xhci_wait_for_event(ctrl, TRB_COMPLETION, timeout_ms);
+ if (!event)
+ return;
+
+ field = le32_to_cpu(event->trans_event.flags);
+ BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
+ xhci_acknowledge_event(ctrl);
+
+ addr = xhci_trb_virt_to_dma(ring->enq_seg,
+ (void *)((uintptr_t)ring->enqueue | ring->cycle_state));
+ xhci_queue_command(ctrl, addr, udev->slot_id, ep_index, TRB_SET_DEQ);
+ event = xhci_wait_for_event(ctrl, TRB_COMPLETION, timeout_ms);
+ if (!event)
+ return;
+
+ BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
+ != udev->slot_id || GET_COMP_CODE(le32_to_cpu(
+ event->event_cmd.status)) != COMP_SUCCESS);
+ xhci_acknowledge_event(ctrl);
+}
+
/*
* Stops transfer processing for an endpoint and throws away all unprocessed
* TRBs by setting the xHC's dequeue pointer to our enqueue pointer. The next
@@ -979,6 +1015,10 @@ int xhci_ctrl_tx(struct usb_device *udev, unsigned long pipe,
record_transfer_result(udev, event, length);
xhci_acknowledge_event(ctrl);
+ if (udev->status == USB_ST_STALLED) {
+ reset_ep(udev, ep_index, timeout_ms);
+ return -EPIPE;
+ }
/* Invalidate buffer to make it available to usb-core */
if (length > 0)
--
2.39.2
