From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Henrik Rydberg" Subject: Re: [PATCH] CHROMIUM: Input: synaptics - filter out the events with low z values Date: Wed, 22 Feb 2012 12:04:59 +0100 Message-ID: <20120222110459.GA28126@polaris.bitmath.org> References: <1329896503-28394-1-git-send-email-cywang@chromium.org> <20120222083858.GA26570@polaris.bitmath.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from smtprelay-b21.telenor.se ([195.54.99.212]:39291 "EHLO smtprelay-b21.telenor.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754152Ab2BVLFM (ORCPT ); Wed, 22 Feb 2012 06:05:12 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Daniel Kurtz Cc: Chung-yih Wang , Alessandro Rubini , Dmitry Torokhov , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Hi Daniel, > > So if num_fingers == 2 and only one of a and b returns > > finger_touched() == true, we fall back to zero fingers? > > Actually, yes. In this case, we will have 2 x's and 2 y's, but not > know which belong to a good finger and which belong to a too light > finger.... sigh... synaptics... sigh... I see the problem. However, ignoring it will just move the problem forward to another bug report, will it not? Hysteresis is a slam dunk here. In addition, since the low-pressure state is bound to be transitional (soon to be followed by a real num_fingers==1 package), simply skipping such packages might be a better option. > > Why not introduce hysteresis for all fingers here? There is an example > > implementation in bcm5974.c in the same directory. > > Good idea, can it be in a different, follow-up patch? Why should it be? Thanks, Henrik