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

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Date:   Thu, 13 Oct 2016 10:54:54 +0300
From:   Felipe Balbi <balbi@...nel.org>
To:     Baolin Wang <baolin.wang@...aro.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


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.

-- 
balbi

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