linux-kernel - Re: [PATCH v2 1/2] usb: dwc3: gadget: Avoid controller stop in .suspend if !softconnect

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Date:   Wed, 3 May 2023 12:28:35 +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 1/2] usb: dwc3: gadget: Avoid controller stop in
 .suspend if !softconnect



On 03/05/2023 00:17, Thinh Nguyen wrote:
> On Tue, May 02, 2023, Roger Quadros wrote:
>> If softconnect is not set it means the controller has not started,
>> so no point in stopping it in dwc3_gadget_suspend()
>>
>> Cc: stable@...r.kernel.org # 5.16
>> Fixes: 8217f07a5023 ("usb: dwc3: gadget: Avoid starting DWC3 gadget during UDC unbind")
> 
> If the reason for this patch is as mentioned in the commit message, then
> I don't think this is a fix patch that needs to be backported to stable.
> The reason why we needed to check both dwc->gadget_driver and
> dwc->softconnect is because of a potential race between resume and
> unbind. Would there be a similar case in dwc_gadget_suspend where a
> potential race may occur? If not, I don't think we need this patch.

OK. I agree.

> 
> Thanks,
> Thinh
> 
>> Signed-off-by: Roger Quadros <rogerq@...nel.org>
>> ---
>>  drivers/usb/dwc3/gadget.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index c0ca4d12f95d..b5170374cd18 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -4656,7 +4656,7 @@ int dwc3_gadget_suspend(struct dwc3 *dwc)
>>  {
>>  	unsigned long flags;
>>  
>> -	if (!dwc->gadget_driver)
>> +	if (!dwc->gadget_driver || !dwc->softconnect)
>>  		return 0;
>>  
>>  	dwc3_gadget_run_stop(dwc, false);
>> -- 
>> 2.34.1

cheers,
-roger