linux-kernel - Re: [PATCH v2 2/2] usb: dwc3: gadget: Improve dwc3_gadget_suspend() and dwc3_gadget

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Date:   Tue, 2 May 2023 21:18:40 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Roger Quadros <rogerq@...nel.org>
CC:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "r-gunasekaran@...com" <r-gunasekaran@...com>,
        "srk@...com" <srk@...com>,
        "wcheng@...eaurora.org" <wcheng@...eaurora.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Subject: Re: [PATCH v2 2/2] usb: dwc3: gadget: Improve dwc3_gadget_suspend()
 and dwc3_gadget_resume()

On Tue, May 02, 2023, Roger Quadros wrote:
> Prevent -ETIMEDOUT error on .suspend().
> e.g. If gadget driver is loaded and we are connected to a USB host,
> all transfers must be stopped before stopping the controller else
> we will not get a clean stop i.e. dwc3_gadget_run_stop() will take
> several seconds to complete and will return -ETIMEDOUT.
> 
> Handle error cases properly in dwc3_gadget_suspend().
> Simplify dwc3_gadget_resume() by using the introduced helper function.
> 
> Fixes: 9f8a67b65a49 ("usb: dwc3: gadget: fix gadget suspend/resume")
> Cc: stable@...r.kernel.org
> Suggested-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
> Signed-off-by: Roger Quadros <rogerq@...nel.org>
> ---
>  drivers/usb/dwc3/gadget.c | 66 +++++++++++++++++++--------------------
>  1 file changed, 33 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index b5170374cd18..869f1695565d 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2699,6 +2699,21 @@ static int dwc3_gadget_soft_disconnect(struct dwc3 *dwc)
>  	return ret;
>  }
>  
> +static int dwc3_gadget_soft_connect(struct dwc3 *dwc)
> +{
> +	/*
> +	 * In the Synopsys DWC_usb31 1.90a programming guide section
> +	 * 4.1.9, it specifies that for a reconnect after a
> +	 * device-initiated disconnect requires a core soft reset
> +	 * (DCTL.CSftRst) before enabling the run/stop bit.
> +	 */
> +	dwc3_core_soft_reset(dwc);
> +
> +	dwc3_event_buffers_setup(dwc);
> +	__dwc3_gadget_start(dwc);
> +	return dwc3_gadget_run_stop(dwc, true);
> +}
> +
>  static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>  {
>  	struct dwc3		*dwc = gadget_to_dwc(g);
> @@ -2737,21 +2752,10 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>  
>  	synchronize_irq(dwc->irq_gadget);
>  
> -	if (!is_on) {
> +	if (!is_on)
>  		ret = dwc3_gadget_soft_disconnect(dwc);
> -	} else {
> -		/*
> -		 * In the Synopsys DWC_usb31 1.90a programming guide section
> -		 * 4.1.9, it specifies that for a reconnect after a
> -		 * device-initiated disconnect requires a core soft reset
> -		 * (DCTL.CSftRst) before enabling the run/stop bit.
> -		 */
> -		dwc3_core_soft_reset(dwc);
> -
> -		dwc3_event_buffers_setup(dwc);
> -		__dwc3_gadget_start(dwc);
> -		ret = dwc3_gadget_run_stop(dwc, true);
> -	}
> +	else
> +		ret = dwc3_gadget_soft_connect(dwc);
>  
>  	pm_runtime_put(dwc->dev);
>  
> @@ -4655,42 +4659,38 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
>  int dwc3_gadget_suspend(struct dwc3 *dwc)
>  {
>  	unsigned long flags;
> +	int ret;
>  
>  	if (!dwc->gadget_driver || !dwc->softconnect)
>  		return 0;
>  
> -	dwc3_gadget_run_stop(dwc, false);
> +	ret = dwc3_gadget_soft_disconnect(dwc);
> +	if (ret)
> +		goto err;
>  
>  	spin_lock_irqsave(&dwc->lock, flags);
>  	dwc3_disconnect_gadget(dwc);
> -	__dwc3_gadget_stop(dwc);
>  	spin_unlock_irqrestore(&dwc->lock, flags);
>  
>  	return 0;
> +
> +err:
> +	/*
> +	 * Attempt to reset the controller's state. Likely no
> +	 * communication can be established until the host
> +	 * performs a port reset.
> +	 */
> +	dwc3_gadget_soft_connect(dwc);
> +
> +	return ret;
>  }
>  
>  int dwc3_gadget_resume(struct dwc3 *dwc)
>  {
> -	int			ret;
> -
>  	if (!dwc->gadget_driver || !dwc->softconnect)
>  		return 0;
>  
> -	ret = __dwc3_gadget_start(dwc);
> -	if (ret < 0)
> -		goto err0;
> -
> -	ret = dwc3_gadget_run_stop(dwc, true);
> -	if (ret < 0)
> -		goto err1;
> -
> -	return 0;
> -
> -err1:
> -	__dwc3_gadget_stop(dwc);
> -
> -err0:
> -	return ret;
> +	return dwc3_gadget_soft_connect(dwc);
>  }
>  
>  void dwc3_gadget_process_pending_events(struct dwc3 *dwc)
> -- 
> 2.34.1
> 

Acked-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>

Thanks,
Thinh