From 6114862b95826a46aede67ce822cb1dc6d4b22c0 Mon Sep 17 00:00:00 2001 From: Jonathan Bell Date: Wed, 11 Aug 2021 15:33:57 +0100 Subject: [PATCH] usb: xhci: workaround for bogus SET_DEQ_PENDING endpoint state See https://github.com/raspberrypi/linux/issues/3981 An unknown unsafe memory access can result in the ep_state variable in xhci_virt_ep being trampled with a stuck SET_DEQ_PENDING state despite successful completion of a Set TR Deq Pointer command. All URB enqueue/dequeue calls for the endpoint will fail in this state so no transfers are possible until the device is reconnected. As a workaround, clear the flag if we see it set and issue a new Set TR Deq command anyway - this should be harmless, as a prior Set TR Deq command will only have been issued in the Stopped state, and if the endpoint is Running then the controller is required to ignore it and respond with a Context State Error event TRB. Signed-off-by: Jonathan Bell --- drivers/usb/host/xhci-ring.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index a120d0c72e5e2..2806b63cc002a 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -732,9 +732,9 @@ static int xhci_move_dequeue_past_td(struct xhci_hcd *xhci, } if ((ep->ep_state & SET_DEQ_PENDING)) { - xhci_warn(xhci, "Set TR Deq already pending, don't submit for 0x%pad\n", - &addr); - return -EBUSY; + xhci_warn(xhci, "WARN A Set TR Deq Ptr command is pending for slot %u ep %u\n", + slot_id, ep_index); + ep->ep_state &= ~SET_DEQ_PENDING; } /* This function gets called from contexts where it cannot sleep */