Re: [PATCH] usb: dwc3: gadget: Queue PM runtime idle on disconnect event

[Greg KH]

On Tue, Jan 02, 2024 at 06:30:23PM -0800, Wesley Cheng wrote:
> There is a scenario where DWC3 runtime suspend is blocked due to the
> dwc->connected flag still being true while PM usage_count is zero after
> DWC3 giveback is completed and the USB gadget session is being terminated.
> This leads to a case where nothing schedules a PM runtime idle for the
> device.
> 
> The exact condition is seen with the following sequence:
>   1.  USB bus reset is issued by the host
>   2.  Shortly after, or concurrently, a USB PD DR SWAP request is received
>       (sink->source)
>   3.  USB bus reset event handler runs and issues
>       dwc3_stop_active_transfers(), and pending transfer are stopped
>   4.  DWC3 usage_count decremented to 0, and runtime idle occurs while
>       dwc->connected == true, returns -EBUSY
>   5.  DWC3 disconnect event seen, dwc->connected set to false due to DR
>       swap handling
>   6.  No runtime idle after this point
> 
> Address this by issuing an asynchronous PM runtime idle call after the
> disconnect event is completed, as it modifies the dwc->connected flag,
> which is what blocks the initial runtime idle.
> 
> Fixes: fc8bb91bc83e ("usb: dwc3: implement runtime PM")
> Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
> ---
>  drivers/usb/dwc3/gadget.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 858fe4c299b7..de6056277f94 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3973,6 +3973,13 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
>  	usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
>  
>  	dwc3_ep0_reset_state(dwc);
> +
> +	/*
> +	 * Request PM idle to address condition where usage count is
> +	 * already decremented to zero, but waiting for the disconnect
> +	 * interrupt to set dwc->connected to FALSE.
> +	 */
> +	pm_request_idle(dwc->dev);
>  }
>  
>  static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
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