Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933902Ab2EXSCE (ORCPT ); Thu, 24 May 2012 14:02:04 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:65450 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933458Ab2EXSCB (ORCPT ); Thu, 24 May 2012 14:02:01 -0400 Date: Thu, 24 May 2012 11:01:54 -0700 From: Dmitry Torokhov To: Linus Torvalds Cc: Greg Kroah-Hartman , Andrew Morton , linux-kernel@vger.kernel.org, linux-input@vger.kernel.org Subject: Re: [git pull] Input updates for 3.5-rc0 Message-ID: <20120524180154.GA15036@core.coreip.homeip.net> References: <20120524083216.GD10562@core.coreip.homeip.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2126 Lines: 60 On Thu, May 24, 2012 at 10:33:49AM -0700, Linus Torvalds wrote: > On Thu, May 24, 2012 at 1:32 AM, Dmitry Torokhov > wrote: > > Hi Linus, > > > > to receive updates for the input subsystem. You will get: > > I get an annoying conflict, and the reason I call it annoying is not > because it's hard to resolve, it's because doing that shows that you > seem to have preferred using > > dev_dbg(&input->dev.parent, ...) > > over the much more natural > > dev_dbg(&input->dev, ...) > > which would seem to make more sense. > > Why? Are the input layer device names so bad that using them for debug > output is useless? And if so, why *are* they so bad? > > I'm going to take your version over Greg's more straightforward one, > because I assume Greg did things a bit more mindlessly and I think you > presumably had a *reason* for your extra (stupid) ".parent" part. But > I'm unhappy with it, because I suspect the reason you did that implies > that the input layer does something bad. A couple of points: 1. A driver should try to use the same device for all its messages and input devices are not created yet at the time we try to bind USB interface to a driver. Most (all?) USB probe() methods use interface's device with dev_xxx() which shows exactly which interface we are dealing with. 2. Input devices are essentially driver-less (they are class devices) and therefore do not provide useful information if used in messages as the format of the message would be: input inputX: some message which does not identify neitehr the driver nor hardware device. By using input->dev.parent we get to the USB interface thus getting more meaningful messages: wacom 2-1.2:1.0: some error happened We had a discussion with Greg about this and he was going to change his patchset to use USB interfaces in the messages... Thanks. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/