From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: input: mt: Software finger tracking in the kernel? Date: Sat, 20 Mar 2010 12:44:24 -0700 Message-ID: <20100320194424.GC28402@core.coreip.homeip.net> References: <4BA358DB.20708@enmesh.se> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-yw0-f172.google.com ([209.85.211.172]:42317 "EHLO mail-yw0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752158Ab0CTToa (ORCPT ); Sat, 20 Mar 2010 15:44:30 -0400 Content-Disposition: inline In-Reply-To: <4BA358DB.20708@enmesh.se> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Henrik Rydberg Cc: linux-input , "linux-kernel@vger.kernel.org" Hi Henrik, On Fri, Mar 19, 2010 at 11:58:35AM +0100, Henrik Rydberg wrote: > Hi Dmitry, > > there is an ongoing discussion about adding multitouch to X > (http://lists.x.org/archives/xorg-devel/2010-March/006206.html), which is > beginning to take on more solid form. > > One of the suggestions emerging from that discussion is to add the software > finger tracking to the kernel. Back in summer 2009 when I thought about this, I > disregarded it as being too experimental. I have since then reconsidered, > starting to think it really is the right place. > > The MT protocol allows applications to take advantage of multi-contact hardware, > but leaves the problems of finger tracking and filtering to the user. Arguably, > no application can make good use of MT without these, so the problem is pushed > forward, in this case to evdev or equivalent. > > The knowledge of signal-to-noise ratios and prior input states resides in the > kernel. Because of this, the finger matching and filtering would naturally > reside within the kernel. > > So, if there were to appear patches to include matching in the input core, would > you consider them? :-) > I am not sure if input core itself is the proper place to do such thing, I'd envisioned something more like a library providing common code that drivers could opt in to use, like we hane ff-memless for memory-less force-feedback devices. Does it make any sense? I guess post the skeleton of the code and we can discuss further. -- Dmitry