From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752247Ab0CTToc (ORCPT ); Sat, 20 Mar 2010 15:44:32 -0400 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 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=r67TZtV6GhV5gPxlBeol7BMyTXnFDdnMtRR2um4kCV9n/bgwiaC+qfgdBsjp7VEnXR 7G77Zy4QdRUaOvFFVW1oH1dV1WxkqZZ52rDQ3uAVbBQtzG6lzWa04thTUN+h2ArOPMm7 gGlv2sjb2RgOGn4GWgMh2NPPbUpQIIUPtfUk8= Date: Sat, 20 Mar 2010 12:44:24 -0700 From: Dmitry Torokhov To: Henrik Rydberg Cc: linux-input , "linux-kernel@vger.kernel.org" Subject: Re: input: mt: Software finger tracking in the kernel? Message-ID: <20100320194424.GC28402@core.coreip.homeip.net> References: <4BA358DB.20708@enmesh.se> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4BA358DB.20708@enmesh.se> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: 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