linux-kernel - Re: [PATCH v4] usb: dwc3: gadget: Stop EP0 transfers during pullup disable

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Date:   Tue, 24 Aug 2021 02:18:40 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Wesley Cheng <wcheng@...eaurora.org>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "jackp@...eaurora.org" <jackp@...eaurora.org>
Subject: Re: [PATCH v4] usb: dwc3: gadget: Stop EP0 transfers during pullup
 disable

Wesley Cheng wrote:
> During a USB cable disconnect, or soft disconnect scenario, a pending
> SETUP transaction may not be completed, leading to the following
> error:
> 
>     dwc3 a600000.dwc3: timed out waiting for SETUP phase
> 
> If this occurs, then the entire pullup disable routine is skipped and
> proper cleanup and halting of the controller does not complete.
> 
> Instead of returning an error (which is ignored from the UDC
> perspective), allow the pullup disable routine to continue, which
> will also handle disabling of EP0/1.  This will end any active
> transfers as well.  Ensure to clear any delayed_status also, as the
> timeout could happen within the STATUS stage.
> 
> Signed-off-by: Wesley Cheng <wcheng@...eaurora.org>
> ---
> Changes in v4:
>  - Fixed formatting and typos in commit text
>  - Removed braces due to the removal of the return statement
> 
> Changes in v3:
>  - Added suggestion by Thinh to change dev_err to dev_warn
> 
> Changes in v2:
>  - Removed calls to dwc3_ep0_end_control_data() and just allow the ep disables
>    on EP0 handle the proper ending of transfers.
>  - Ensure that delayed_status is cleared, as ran into enumeration issues if the
>    SETUP transaction fails on a STATUS stage.  Saw delayed_status == TRUE on the
>    next connect, which blocked further SETUP transactions to be handled.
> 
>  drivers/usb/dwc3/gadget.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 5d084542718d..63f6d9f2a692 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2428,10 +2428,8 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>  
>  		ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
>  				msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
> -		if (ret == 0) {
> -			dev_err(dwc->dev, "timed out waiting for SETUP phase\n");
> -			return -ETIMEDOUT;
> -		}
> +		if (ret == 0)
> +			dev_warn(dwc->dev, "timed out waiting for SETUP phase\n");
>  	}
>  
>  	/*
> @@ -2643,6 +2641,7 @@ static int __dwc3_gadget_start(struct dwc3 *dwc)
>  	/* begin to receive SETUP packets */
>  	dwc->ep0state = EP0_SETUP_PHASE;
>  	dwc->link_state = DWC3_LINK_STATE_SS_DIS;
> +	dwc->delayed_status = false;
>  	dwc3_ep0_out_start(dwc);
>  
>  	dwc3_gadget_enable_irq(dwc);
> 

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

Thanks,
Thinh