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

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Message-ID: <20200529135524.GA14614@qmqm.qmqm.pl>
Date:   Fri, 29 May 2020 15:55:24 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Peter Chen <peter.chen@....com>
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Robert Baldyga <r.baldyga@...sung.com>,
        "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb: gadget: f_acm: don't disable disabled EP

On Fri, May 29, 2020 at 08:10:40AM +0000, Peter Chen wrote:
> On 20-05-28 20:30:28, Michał Mirosław wrote:
> > Make debugging real problems easier by not trying to disable an EP that
> > was not yet enabled.
> > 
> > Fixes: 4aab757ca44a ("usb: gadget: f_acm: eliminate abuse of ep->driver data")
> > Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> > ---
> >  drivers/usb/gadget/function/f_acm.c | 8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/usb/gadget/function/f_acm.c b/drivers/usb/gadget/function/f_acm.c
> > index 200596ea9557..46647bfac2ef 100644
> > --- a/drivers/usb/gadget/function/f_acm.c
> > +++ b/drivers/usb/gadget/function/f_acm.c
> > @@ -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.

Best Regards,
Michał Mirosław