Commit 1b967691 authored May 24, 2020 by Bin Liu Committed by Greg Kroah-Hartman May 25, 2020

usb: musb: return -ESHUTDOWN in urb when three-strikes error happened

When a USB device attached to a hub got disconnected, MUSB controller
generates RXCSR_RX_ERROR interrupt for the 3-strikes-out error.

Currently the MUSB host driver returns -EPROTO in current URB, then the
USB device driver could immediately resubmit the URB which causes MUSB
generate RXCSR_RX_ERROR interrupt again. This circle causes interrupt
storm then the hub never got a chance to report the USB device detach.

To fix the interrupt storm, change the URB return code to -ESHUTDOWN for
MUSB_RXCSR_H_ERROR interrupt, so that the USB device driver will not
immediately resubmit the URB.

Signed-off-by: Bin Liu <b-liu@ti.com>
Link: https://lore.kernel.org/r/20200525025049.3400-2-b-liu@ti.com

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent ca681aa4

drivers/usb/musb/musb_host.c

+8 −2

Original line number	Diff line number	Diff line
		@@ -1774,9 +1774,15 @@ void musb_host_rx(struct musb *musb, u8 epnum)
		status = -EPIPE;

		} else if (rx_csr & MUSB_RXCSR_H_ERROR) {
		musb_dbg(musb, "end %d RX proto error", epnum);
		dev_err(musb->controller, "ep%d RX three-strikes error", epnum);

		status = -EPROTO;
		/*
		* The three-strikes error could only happen when the USB
		* device is not accessible, for example detached or powered
		* off. So return the fatal error -ESHUTDOWN so hopefully the
		* USB device drivers won't immediately resubmit the same URB.
		*/
		status = -ESHUTDOWN;
		musb_writeb(epio, MUSB_RXINTERVAL, 0);

		rx_csr &= ~MUSB_RXCSR_H_ERROR;

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