[PATCH 5.4 11/27] usb: dwc3: gadget: Avoid runtime resume if disabling pullup

Greg Kroah-Hartman
2021-08-13T15:18:01Z

From: Wesley Cheng <wcheng@codeaurora.org>

[ Upstream commit cb10f68ad8150f243964b19391711aaac5e8ff42 ]

If the device is already in the runtime suspended state, any call to
the pullup routine will issue a runtime resume on the DWC3 core
device. If the USB gadget is disabling the pullup, then avoid having
to issue a runtime resume, as DWC3 gadget has already been
halted/stopped.

This fixes an issue where the following condition occurs:

usb_gadget_remove_driver()
-->usb_gadget_disconnect()
-->dwc3_gadget_pullup(0)
-->pm_runtime_get_sync() -> ret = 0
-->pm_runtime_put() [async]
-->usb_gadget_udc_stop()
-->dwc3_gadget_stop()
-->dwc->gadget_driver = NULL
...

dwc3_suspend_common()
-->dwc3_gadget_suspend()
-->DWC3 halt/stop routine skipped, driver_data == NULL

This leads to a situation where the DWC3 gadget is not properly
stopped, as the runtime resume would have re-enabled EP0 and event
interrupts, and since we avoided the DWC3 gadget suspend, these
resources were never disabled.

Fixes: 77adb8bdf422 ("usb: dwc3: gadget: Allow runtime suspend if UDC unbinded")
Cc: stable <stable@vger.kernel.org>
Acked-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Link: https://lore.kernel.org/r/1628058245-30692-1-git-send-email-wcheng@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/dwc3/gadget.c | 11 +++++++++++
1 file changed, 11 insertions(+)

--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -2019,6 +2019,17 @@ static int dwc3_gadget_pullup(struct usb
}

/*
+ * Avoid issuing a runtime resume if the device is already in the
+ * suspended state during gadget disconnect. DWC3 gadget was already
+ * halted/stopped during runtime suspend.
+ */
+ if (!is_on) {
+ pm_runtime_barrier(dwc->dev);
+ if (pm_runtime_suspended(dwc->dev))
+ return 0;
+ }
+
+ /*
* Check the return value for successful resume, or error. For a
* successful resume, the DWC3 runtime PM resume routine will handle
* the run stop sequence, so avoid duplicate operations here.