Re: [PATCH 2/3] usbtouchscreen: Implement runtime power management

From: Alan Stern <stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>
To: Oliver Neukum <oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org>
Cc: Dmitry Torokhov
	<dmitry.torokhov-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	linux-input-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Daniel Ritz <daniel.ritz-OI3hZJvNYWs@public.gmane.org>
Subject: Re: [PATCH 2/3] usbtouchscreen: Implement runtime power management
Date: Mon, 7 Jun 2010 16:22:54 -0400 (EDT)	[thread overview]
Message-ID: <Pine.LNX.4.44L0.1006071622260.1332-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <201006072131.18949.oliver-GvhC2dPhHPQdnm+yROfE0A@public.gmane.org>

On Mon, 7 Jun 2010, Oliver Neukum wrote:

> Am Montag, 7. Juni 2010 18:23:16 schrieb Dmitry Torokhov:
> > On Mon, Jun 07, 2010 at 03:13:42PM +0200, Oliver Neukum wrote:
> > >  static int usbtouch_open(struct input_dev *input)
> > >  {
> > >  	struct usbtouch_usb *usbtouch = input_get_drvdata(input);
> > > +	int r;
> > >  
> > >  	usbtouch->irq->dev = interface_to_usbdev(usbtouch->interface);
> > >  
> > > +	r = usb_autopm_get_interface(usbtouch->interface) ? -EIO : 0;
> > 
> > Why are we clobbering error code with -EIO? We should propagate te code
> > returned to us (here and below).
> 
> usb_autopm_get_interface() uses internal USB error codes which with
> a few exceptions, do not have the meaning error codes in user space
> have.

But other drivers don't do this.  What's special about usbtouch?

Alan Stern

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