From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [RFC][PATCH] input: Introduce device information ioctl Date: Tue, 7 Dec 2010 08:51:01 -0800 Message-ID: <20101207165101.GB25344@core.coreip.homeip.net> References: <1291706726-8835-1-git-send-email-rydberg@euromail.se> <20101207091653.GA22416@core.coreip.homeip.net> <201012071340.26244.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-iw0-f174.google.com ([209.85.214.174]:49352 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751736Ab0LGQvJ (ORCPT ); Tue, 7 Dec 2010 11:51:09 -0500 Content-Disposition: inline In-Reply-To: <201012071340.26244.arnd@arndb.de> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Arnd Bergmann Cc: Kay Sievers , Henrik Rydberg , Jiri Kosina , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Ping Cheng , Chris Bagwell On Tue, Dec 07, 2010 at 01:40:26PM +0100, Arnd Bergmann wrote: > On Tuesday 07 December 2010, Kay Sievers wrote: > > On Tue, Dec 7, 2010 at 10:16, Dmitry Torokhov wrote: > > > Hi Henrik, > > > > > > On Tue, Dec 07, 2010 at 08:25:26AM +0100, Henrik Rydberg wrote: > > >> Today, userspace sets up an input device based on the data it emits. > > >> This is not always enough; a tablet and a touchscreen may emit exactly > > >> the same data, for instance, but the former should be set up with a > > >> pointer whereas the latter does not need to. Recently, a new type of > > >> touchpad has emerged where the buttons are under the pad, which changes > > >> handling logic without changing the emitted data. This patch introduces > > >> a new ioctl, EVIOCGDEVINFO, which allows userspace to extract information > > >> about the device resulting in proper setup. > > > > > > If we agree that the new ioctl is suitable we'llalso need to wireit up > > > through sysfs. Also, can we keep all definitions to INPUT_ namespace? > > > > Please don't add new ioctls which are not extensible. The ioctl should > > carry the length or the version of the structure it asks for, so it > > can be extended in the future. Sysfs should be good enough for such > > interface though. > > Please never add any ioctls that have a version or length field! > > Ideally ioctls should have only scalar arguments, not structures, > so I'd recommend splitting it into two, so you can read type and > capability parameters separately. Yes, I think it is a good idea to turn it into 2 scalar ioctls. -- Dmitry