linux-kernel - Re: [PATCH] usb: dwc3: Prevent indefinite sleep in _dwc3_set

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Message-ID: <87sh9l5z4l.fsf@linux.intel.com>
Date:   Wed, 28 Feb 2018 09:53:14 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     Roger Quadros <rogerq@...com>
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Roger Quadros <rogerq@...com>
Subject: Re: [PATCH] usb: dwc3: Prevent indefinite sleep in _dwc3_set_mode during suspend/resume


Hi,

Roger Quadros <rogerq@...com> writes:
> In the following test we get stuck by sleeping forever in _dwc3_set_mode()
> after which dual-role switching doesn't work.
>
> On dra7-evm's dual-role port,
> - Load g_zero gadget driver and enumerate to host
> - suspend to mem
> - disconnect USB cable to host and connect otg cable with Pen drive in it.
> - resume system
> - we sleep indefinitely in _dwc3_set_mode due to.
>   dwc3_gadget_exit()->usb_del_gadget_udc()->udc_stop()->
> 	dwc3_gadget_stop()->wait_event_lock_irq()
>
> Let's clear the DWC3_EP_END_TRANSFER_PENDING flag on all endpoints
> so we don't wait in dwc3_gadget_stop().
>
> Signed-off-by: Roger Quadros <rogerq@...com>
> ---
>  drivers/usb/dwc3/gadget.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 2bda4eb..0a360da 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -3273,6 +3273,20 @@ int dwc3_gadget_init(struct dwc3 *dwc)
>  
>  void dwc3_gadget_exit(struct dwc3 *dwc)
>  {
> +	int epnum;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&dwc->lock, flags);
> +	for (epnum = 2; epnum < DWC3_ENDPOINTS_NUM; epnum++) {
> +		struct dwc3_ep  *dep = dwc->eps[epnum];
> +
> +		if (!dep)
> +			continue;
> +
> +		dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
> +	}
> +	spin_unlock_irqrestore(&dwc->lock, flags);
> +
>  	usb_del_gadget_udc(&dwc->gadget);
>  	dwc3_gadget_free_endpoints(dwc);

free endpoints is a better place for this. It's already going to free
the memory anyway. Might as well clear all flags to 0 there.

-- 
balbi

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