linux-kernel - Re: [PATCH v4 6/9] usb: dwc3: Remove DWC3 locking during gadget suspend/resume

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Date:   Tue, 23 Aug 2022 01:14:29 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Wesley Cheng <quic_wcheng@...cinc.com>
CC:     "balbi@...nel.org" <balbi@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "quic_jackp@...cinc.com" <quic_jackp@...cinc.com>
Subject: Re: [PATCH v4 6/9] usb: dwc3: Remove DWC3 locking during gadget
 suspend/resume

On Wed, Aug 17, 2022 at 11:23:56AM -0700, Wesley Cheng wrote:
> Remove the need for making dwc3_gadget_suspend() and dwc3_gadget_resume()
> to be called in a spinlock, as dwc3_gadget_run_stop() could potentially
> take some time to complete.
> 
> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
> ---
>  drivers/usb/dwc3/core.c   | 4 ----
>  drivers/usb/dwc3/gadget.c | 5 +++++
>  2 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index c5c238ab3083..23e123a1ab5f 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1976,9 +1976,7 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  	case DWC3_GCTL_PRTCAP_DEVICE:
>  		if (pm_runtime_suspended(dwc->dev))
>  			break;
> -		spin_lock_irqsave(&dwc->lock, flags);
>  		dwc3_gadget_suspend(dwc);
> -		spin_unlock_irqrestore(&dwc->lock, flags);
>  		synchronize_irq(dwc->irq_gadget);
>  		dwc3_core_exit(dwc);
>  		break;
> @@ -2039,9 +2037,7 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>  			return ret;
>  
>  		dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_DEVICE);
> -		spin_lock_irqsave(&dwc->lock, flags);
>  		dwc3_gadget_resume(dwc);
> -		spin_unlock_irqrestore(&dwc->lock, flags);
>  		break;
>  	case DWC3_GCTL_PRTCAP_HOST:
>  		if (!PMSG_IS_AUTO(msg) && !device_can_wakeup(dwc->dev)) {
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 7b66a54250a0..57d83b3b4967 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -4520,12 +4520,17 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
>  
>  int dwc3_gadget_suspend(struct dwc3 *dwc)
>  {
> +	unsigned long flags;
> +
>  	if (!dwc->gadget_driver)
>  		return 0;
>  
>  	dwc3_gadget_run_stop(dwc, false, false);
> +
> +	spin_lock_irqsave(&dwc->lock, flags);
>  	dwc3_disconnect_gadget(dwc);
>  	__dwc3_gadget_stop(dwc);
> +	spin_unlock_irqrestore(&dwc->lock, flags);
>  
>  	return 0;
>  }

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

Thanks,
Thinh