linux-kernel - Re: [PATCH v2 4/5] usb: dwc3: Allow end transfer commands to be sent during soft disconnect

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Date:   Thu, 21 Jul 2022 22:08:55 +0000
From:   Thinh Nguyen <Thinh.Nguyen@...opsys.com>
To:     Wesley Cheng <quic_wcheng@...cinc.com>,
        "balbi@...nel.org" <balbi@...nel.org>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>
CC:     "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>,
        Thinh Nguyen <Thinh.Nguyen@...opsys.com>
Subject: Re: [PATCH v2 4/5] usb: dwc3: Allow end transfer commands to be sent
 during soft disconnect

Hi Wesley,

On 7/12/2022, Wesley Cheng wrote:
> If soft disconnect is in progress, allow the endxfer command to be sent,
> without this, there is an issue where the stop active transfer call
> (during pullup disable) wouldn't actually issue the endxfer command,
> while clearing the DEP flag.
>
> In addition, if the DWC3_EP_DELAY_STOP flag was set before soft disconnect
> started (i.e. from the dequeue path), ensure that when the EP0 transaction
> completes during soft disconnect, to issue the endxfer with the force
> parameter set, as it does not expect a command complete event.
>
> Fixes: e4cf6580ac740 ("usb: dwc3: gadget: Wait for ep0 xfers to complete during dequeue")
> Suggested-by: Thinh Nguyen <Thinh.Nguyen@...opsys.com>
> Signed-off-by: Wesley Cheng <quic_wcheng@...cinc.com>
> ---
> Link:
>    https://urldefense.com/v3/__https://lore.kernel.org/linux-usb/1a1a5485-790e-79ce-f5a6-1e96d9b49a47@synopsys.com/__;!!A4F2R9G_pg!cXW2TlALYWnXNPg-NoMFUrQ8K1egEZiQizZ5CA1DOM1Gcw4tfOULy-_2eMGvL8pQPte5dScFON-0wxH2eXu8ijEQUbs$
>
>   drivers/usb/dwc3/ep0.c    | 3 +--
>   drivers/usb/dwc3/gadget.c | 5 ++++-
>   2 files changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> index 506ef717fdc0..5851b0e9db0a 100644
> --- a/drivers/usb/dwc3/ep0.c
> +++ b/drivers/usb/dwc3/ep0.c
> @@ -290,8 +290,7 @@ void dwc3_ep0_out_start(struct dwc3 *dwc)
>   		if (!(dwc3_ep->flags & DWC3_EP_DELAY_STOP))
>   			continue;
>   
> -		dwc3_ep->flags &= ~DWC3_EP_DELAY_STOP;

If we don't clear this flag here,

> -		dwc3_stop_active_transfer(dwc3_ep, true, true);
> +		dwc3_stop_active_transfer(dwc3_ep, true, dwc->connected);
>   	}
>   }
>   
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index ee85b773e3fe..41b7007358de 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1693,6 +1693,7 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
>   		dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
>   	else if (!ret)
>   		dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
> +	dep->flags &= ~DWC3_EP_DELAY_STOP;
>   
>   	return ret;
>   }
> @@ -3686,8 +3687,10 @@ void dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force,
>   	if (dep->number <= 1 && dwc->ep0state != EP0_DATA_PHASE)
>   		return;
>   
> +	if (interrupt && (dep->flags & DWC3_EP_DELAY_STOP))
> +		return;
> +

then it may not go through here. I think I made this same mistake in my 
previous suggestion.

>   	if (!(dep->flags & DWC3_EP_TRANSFER_STARTED) ||
> -	    (dep->flags & DWC3_EP_DELAY_STOP) ||
>   	    (dep->flags & DWC3_EP_END_TRANSFER_PENDING))
>   		return;
>   

Thanks,
Thinh