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 02:56:20 -0800 Message-ID: <20101207105620.GB23729@core.coreip.homeip.net> References: <1291706726-8835-1-git-send-email-rydberg@euromail.se> <20101207091653.GA22416@core.coreip.homeip.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-px0-f174.google.com ([209.85.212.174]:36084 "EHLO mail-px0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751856Ab0LGK40 (ORCPT ); Tue, 7 Dec 2010 05:56:26 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Kay Sievers Cc: Henrik Rydberg , Jiri Kosina , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Ping Cheng , Chris Bagwell On Tue, Dec 07, 2010 at 11:48:28AM +0100, 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. Size of ioctl data is encoded in ioctl, it can be extended easily. For examples take a look at how EVIOCGKEYCODE and EVIOCGSKEYCODE are handled in recent kernels. > Sysfs should be good enough for such > interface though. > -- Dmitry