Commit 7252f1bf authored Mar 15, 2015 by Vincent Palatin Committed by Felipe Balbi Mar 19, 2015

usb: dwc2: avoid leaking DMA channels on disconnection



When the HCD is disconnected, the DMA transfers still in-flight were cleaned-up
but the count of available DMA channels (e.g. available_host_channels) was not
reset.
The pool of DMA channels can be depleted when doing unclean
disconnection of USB peripherals, and reaches the point where no
transfer was possible until the next reboot/reload of the driver.

Tested by putting a programmable USB mux on the port and randomly
plugging/unpluging a USB HUB with USB mass-storage key, USB-audio and
USB-ethernet dongle connected to its downstream ports, and also doing the
disconnection early while the devices are still enumerating to get more URBs
in-flight.
After the patch, the devices are still enumerating after thousands of cycles,
while the port was totally dead before.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>
Acked-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

parent 46f5cace

drivers/usb/dwc2/hcd.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -257,6 +257,14 @@ static void dwc2_hcd_cleanup_channels(struct dwc2_hsotg *hsotg)
		*/
		channel->qh = NULL;
		}
		/* All channels have been freed, mark them available */
		if (hsotg->core_params->uframe_sched > 0) {
		hsotg->available_host_channels =
		hsotg->core_params->host_channels;
		} else {
		hsotg->non_periodic_channels = 0;
		hsotg->periodic_channels = 0;
		}
		}

		/**

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