From mboxrd@z Thu Jan 1 00:00:00 1970 From: Trilok Soni Subject: Re: input: mt: Software finger tracking in the kernel? Date: Fri, 19 Mar 2010 17:08:28 +0530 Message-ID: <5d5443651003190438s17330100vc1d91c9089f7e7f2@mail.gmail.com> References: <4BA358DB.20708@enmesh.se> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Return-path: In-Reply-To: <4BA358DB.20708@enmesh.se> Sender: linux-kernel-owner@vger.kernel.org To: Henrik Rydberg Cc: Dmitry Torokhov , linux-input , "linux-kernel@vger.kernel.org" List-Id: linux-input@vger.kernel.org Hi Henrik, On Fri, Mar 19, 2010 at 4:28 PM, 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? :-) Please post your patches for the further discussion. Last time I referred the Android userspace code it was also not using TRACKING_ID as defined in MT protocol even if the kernel driver emits them. -- ---Trilok Soni http://triloksoni.wordpress.com http://www.linkedin.com/in/triloksoni