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

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Date:   Tue, 2 May 2023 21:17:58 +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 1/2] usb: dwc3: gadget: Avoid controller stop in
 .suspend if !softconnect

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.

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
>