From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753184Ab0H3NZp (ORCPT ); Mon, 30 Aug 2010 09:25:45 -0400 Received: from cantor2.suse.de ([195.135.220.15]:46908 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751972Ab0H3NZn (ORCPT ); Mon, 30 Aug 2010 09:25:43 -0400 Date: Mon, 30 Aug 2010 15:25:41 +0200 (CEST) From: Jiri Kosina To: Rafi Rubin Cc: Henrik Rydberg , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, dmitry.torokhov@gmail.com, chatty@enac.fr, micki@n-trig.com Subject: Re: [PATCH 1/4] Adding documention In-Reply-To: <4C7ABA64.50005@seas.upenn.edu> Message-ID: References: <1282798497-19791-1-git-send-email-rafi@seas.upenn.edu> <1282798497-19791-2-git-send-email-rafi@seas.upenn.edu> <4C77AA45.4030805@euromail.se> <4C7ABA64.50005@seas.upenn.edu> User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 29 Aug 2010, Rafi Rubin wrote: > >> +---------- > >> + > >> +Note: values set at load time are global and will apply to all applicable > >> +devices. Adjusting parameters with sysfs will override the load time values, > >> +but only for that one device. > >> + > >> +The following parameters are used to configure filters to reduce noise: > >> + > >> +activate_slack number of fingers to ignore before processing events > >> + > >> +activation_height size threshold to activate immediately > >> +activation_width > >> + > >> +min_height size threshold bellow which fingers are ignored > >> +min_width both to decide activation and during activity > >> + > >> +deactivate_slack the number of "no contact" frames to ignore before > >> + propagating the end of activity events > >> + > >> +When the last finger is removed from the device, it sends a number of empty > >> +frames. By holding off on deactivation for a few frames we can tolerate false > >> +erroneous disconnects, where the sensor may mistakenly not detect a finger that > >> +is still present. Thus deactivate_slack addresses problems where a users might > >> +see breaks in lines during drawing, or drop an object during a long drag. > > > > > > Without contact tracking, it is hard to imagine activation filtering to work > > properly. I would advocate to remove this functionality from the driver, and add > > it in userspace instead. > > > > Henrik > > I don't think its quite time to remove these filters. There still isn't a > proper replacement that's readily accessible to most users. From what I've > heard many still use the wacom driver to support touch in X. > > Tracking only helps if you increase the activation slack to more than 1 contact > (the current default), and only if you assume the you will see ghosts span > multiple frames in two different locations, which may be even less likely than > seeing a ghost in one spot for two frames. > > Maybe in a few more months or another year, it will make more sense to remove > the filters from this driver. In the mean time, is it really preferable to > leave them undocumented? Agreed. I have now applied the patch, thanks Rafi. -- Jiri Kosina SUSE Labs, Novell Inc.