Hi Wesley,
On Fri, Jul 30, 2021 at 05:29:34PM -0700, Wesley Cheng wrote:
> 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.
>
> Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
> ---
> drivers/usb/dwc3/gadget.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index a29a4ca..5d08454 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2435,6 +2435,17 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
> }
>
> /*
> + * 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.
Should this also go to stable with Fixes: 77adb8bdf422 ("usb: dwc3:
gadget: Allow runtime suspend if UDC unbinded") ?
Jack
