linux-kernel - Re: [RESEND PATCH v3 2/2] usb: dwc3: Wait for control tranfer completed when stopping gadget

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Message-ID: <CAMz4ku+UaxeyRje-nEiJQ2xzR7bUtkPzvydHuMPiFYuVYde48A@mail.gmail.com>
Date:   Thu, 13 Oct 2016 16:01:45 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Felipe Balbi <balbi@...nel.org>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Mark Brown <broonie@...nel.org>,
        USB <linux-usb@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v3 2/2] usb: dwc3: Wait for control tranfer
 completed when stopping gadget

On 13 October 2016 at 15:54, Felipe Balbi <balbi@...nel.org> wrote:
>
> Hi,
>
> Baolin Wang <baolin.wang@...aro.org> writes:
>> Hi,
>>
>> On 13 October 2016 at 15:08, Felipe Balbi <balbi@...nel.org> wrote:
>>>
>>> Hi,
>>>
>>> Baolin Wang <baolin.wang@...aro.org> writes:
>>>> @@ -1487,10 +1496,22 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>>>>
>>>>       is_on = !!is_on;
>>>>
>>>> +try_again:
>>>>       spin_lock_irqsave(&dwc->lock, flags);
>>>>       ret = dwc3_gadget_run_stop(dwc, is_on, false);
>>>>       spin_unlock_irqrestore(&dwc->lock, flags);
>>>>
>>>> +     if (ret == -EBUSY) {
>>>> +             ret = wait_for_completion_timeout(&dwc->ep0_in_setup,
>>>> +                                               msecs_to_jiffies(500));
>>>> +             if (ret == 0) {
>>>> +                     dev_err(dwc->dev, "timeout to stop gadget.\n");
>>>> +                     ret = -ETIMEDOUT;
>>>> +             } else {
>>>> +                     goto try_again;
>>>
>>> you are not really reading my comments. It's the third time I tell you
>>> there's no need for try_again. If you can't complete a control transfer
>>> in 500ms, you already have other issues. Take this thing out of here.
>>
>> I think you misunderstood the code. If there is 500ms timeout, we will
>> return '-ETIMEDOUT' error. If the control transfer is completed before
>> timeout, we can not just return and we need try again to stop the
>> gadget, right? Any other good suggestion? Thanks.
>
> Yeah, change the patch a bit so you wait for completion before calling
> dwc3_gadget_runt_stop()? I mean, move the !is_on && ep0_state check
> before calling dwc3_gadget_run_stop() and wait_for_completion_timeout()
> there.

OK. I will refactor the patch. Thanks.

>
> --
> balbi



-- 
Baolin.wang
Best Regards