linux-kernel - Re: [PATCH] usb: gadget: f_acm: don't disable disabled EP

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Date:   Wed, 01 Jul 2020 09:54:42 +0300
From:   Felipe Balbi <balbi@...nel.org>
To:     Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Peter Chen <peter.chen@....com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-usb\@vger.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: gadget: f_acm: don't disable disabled EP

Michał Mirosław <mirq-linux@...e.qmqm.pl> writes:

> On Sat, May 30, 2020 at 01:03:17AM +0000, Peter Chen wrote:
>>  
>> > > > @@ -425,9 +425,11 @@ static int acm_set_alt(struct usb_function *f, unsigned
>> > intf, unsigned alt)
>> > > >  	/* we know alt == 0, so this is an activation or a reset */
>> > > >
>> > > >  	if (intf == acm->ctrl_id) {
>> > > > -		dev_vdbg(&cdev->gadget->dev,
>> > > > -				"reset acm control interface %d\n", intf);
>> > > > -		usb_ep_disable(acm->notify);
>> > > > +		if (acm->notify->enabled) {
>> > > > +			dev_vdbg(&cdev->gadget->dev,
>> > > > +					"reset acm control interface %d\n", intf);
>> > > > +			usb_ep_disable(acm->notify);
>> > > > +		}
>> > >
>> > > But it does not fix any issues, the usb_ep_disable checks 'enabled' flag.
>> > 
>> > It generates spurious trace events if you enable them.
>> You mean the trace events from core.c? If it is, we could try to improve it
>> and indicate it is already enabled or disabled.
>
> It is indicated in return code, but the problem is that this generates
> noise and wastes debugging time. The problem I was seeing manifested
> itself as disabling disabled EPs and desync of EP state between core
> and UDC driver. The patch avoids the noise and makes the code obvious.
> (This check was there at some point in time, BTW.)

I agree with this as well. But still, $subject doesn't look like a
candidate for the -rc :-) I'll apply it for the next merge window.

-- 
balbi

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