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

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Message-ID: <81124fee-1fce-97a5-07f8-833250674b64@kernel.org>
Date:   Wed, 3 May 2023 12:30:40 +0300
From:   Roger Quadros <rogerq@...nel.org>
To:     Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Cc:     "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 03/05/2023 00:18, Thinh Nguyen wrote:
> 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:

As we don't pick the first patch, we will need to check for dwc->softconnect
here.

I'll send a follow up patch.

>> +	/*
>> +	 * 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

cheers,
-roger