88 lines
3.2 KiB
Diff
88 lines
3.2 KiB
Diff
From c942eb452c1c31fe6259178b6e9fea5456d7fb9c Mon Sep 17 00:00:00 2001
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Message-Id: <c942eb452c1c31fe6259178b6e9fea5456d7fb9c.1654086219.git.stefan@agner.ch>
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In-Reply-To: <24b77460dbfa2497ceb7a1611bf28b6eb88a1d74.1654086219.git.stefan@agner.ch>
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References: <24b77460dbfa2497ceb7a1611bf28b6eb88a1d74.1654086219.git.stefan@agner.ch>
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From: Stefan Agner <stefan@agner.ch>
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Date: Mon, 27 Sep 2021 12:28:04 +0200
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Subject: [PATCH] usb: xhci: reset endpoint on USB stall
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There are devices which cause a USB stall when trying to read strings.
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Specifically Arduino Mega R3 stalls when trying to read the product
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string.
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The stall currently remains unhandled, and subsequent retries submit new
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transfers on a stopped endpoint which ultimately cause a crash in
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abort_td():
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WARN halted endpoint, queueing URB anyway.
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XHCI control transfer timed out, aborting...
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Unexpected XHCI event TRB, skipping... (3affe040 00000000 13000000 02008401)
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BUG at drivers/usb/host/xhci-ring.c:505/abort_td()!
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BUG!
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resetting ...
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Linux seems to be able to recover from the stall by issuing a
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TRB_RESET_EP command.
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Introduce reset_ep() which issues a TRB_RESET_EP followed by setting the
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transfer ring dequeue pointer via TRB_SET_DEQ. This allows to properly
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recover from a USB stall error and continue communicating with the USB
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device.
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Signed-off-by: Stefan Agner <stefan@agner.ch>
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---
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drivers/usb/host/xhci-ring.c | 31 +++++++++++++++++++++++++++++++
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1 file changed, 31 insertions(+)
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diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c
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index 35bd5cd29e..430823cb9d 100644
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--- a/drivers/usb/host/xhci-ring.c
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+++ b/drivers/usb/host/xhci-ring.c
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@@ -481,6 +481,33 @@ union xhci_trb *xhci_wait_for_event(struct xhci_ctrl *ctrl, trb_type expected)
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BUG();
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}
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+/*
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+ * Issue reset endpoint command for an endpoint. This is required to recover
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+ * a halted endpoint (e.g. due to a stall error).
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+ */
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+static void reset_ep(struct usb_device *udev, int ep_index)
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+{
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+ struct xhci_ctrl *ctrl = xhci_get_ctrl(udev);
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+ struct xhci_ring *ring = ctrl->devs[udev->slot_id]->eps[ep_index].ring;
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+ union xhci_trb *event;
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+ u32 field;
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+
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+ printf("Resetting EP...\n");
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+ xhci_queue_command(ctrl, NULL, udev->slot_id, ep_index, TRB_RESET_EP);
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+ event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
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+ field = le32_to_cpu(event->trans_event.flags);
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+ BUG_ON(TRB_TO_SLOT_ID(field) != udev->slot_id);
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+ xhci_acknowledge_event(ctrl);
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+
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+ xhci_queue_command(ctrl, (void *)((uintptr_t)ring->enqueue |
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+ ring->cycle_state), udev->slot_id, ep_index, TRB_SET_DEQ);
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+ event = xhci_wait_for_event(ctrl, TRB_COMPLETION);
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+ BUG_ON(TRB_TO_SLOT_ID(le32_to_cpu(event->event_cmd.flags))
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+ != udev->slot_id || GET_COMP_CODE(le32_to_cpu(
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+ event->event_cmd.status)) != COMP_SUCCESS);
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+ xhci_acknowledge_event(ctrl);
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+}
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+
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/*
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* Stops transfer processing for an endpoint and throws away all unprocessed
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* TRBs by setting the xHC's dequeue pointer to our enqueue pointer. The next
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@@ -928,6 +955,10 @@ int xhci_ctrl_tx(struct usb_device *udev, unsigned long pipe,
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record_transfer_result(udev, event, length);
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xhci_acknowledge_event(ctrl);
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+ if (udev->status == USB_ST_STALLED) {
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+ reset_ep(udev, ep_index);
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+ return -EPIPE;
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+ }
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/* Invalidate buffer to make it available to usb-core */
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if (length > 0)
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--
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2.36.1
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