From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Henrik Rydberg" <rydberg@euromail.se>
Subject: Re: [PATCH] CHROMIUM: Input: synaptics - filter out the events with
 low z values
Date: Fri, 24 Feb 2012 10:23:51 +0100
Message-ID: <20120224092351.GA2203@polaris.bitmath.org>
References: <1329896503-28394-1-git-send-email-cywang@chromium.org>
 <20120222083858.GA26570@polaris.bitmath.org>
 <CAGS+omCU9f=DyC442+4HOF=sGhZYXne+E2ephFiOmuj-XKciMA@mail.gmail.com>
 <20120222110459.GA28126@polaris.bitmath.org>
 <CAGS+omB0GCQHOjrb_T6h7DzHrH2sp4Xqb5av6JC-ttJ8HZ5BcQ@mail.gmail.com>
 <20120222152425.GA29436@polaris.bitmath.org>
 <20120224082706.GB18291@core.coreip.homeip.net>
 <20120224090835.GA2154@polaris.bitmath.org>
 <20120224091452.GD10763@core.coreip.homeip.net>
 <20120224091602.GE10763@core.coreip.homeip.net>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Return-path: <linux-input-owner@vger.kernel.org>
Received: from smtprelay-b22.telenor.se ([195.54.99.213]:60809 "EHLO
	smtprelay-b22.telenor.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1755604Ab2BXJX4 (ORCPT
	<rfc822;linux-input@vger.kernel.org>);
	Fri, 24 Feb 2012 04:23:56 -0500
Content-Disposition: inline
In-Reply-To: <20120224091602.GE10763@core.coreip.homeip.net>
Sender: linux-input-owner@vger.kernel.org
List-Id: linux-input@vger.kernel.org
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Daniel Kurtz <djkurtz@chromium.org>, Chung-yih Wang <cywang@chromium.org>, Alessandro Rubini <rubini@ipvvis.unipv.it>, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org

On Fri, Feb 24, 2012 at 01:16:02AM -0800, Dmitry Torokhov wrote:
> On Fri, Feb 24, 2012 at 01:14:52AM -0800, Dmitry Torokhov wrote:
> > On Fri, Feb 24, 2012 at 10:08:35AM +0100, Henrik Rydberg wrote:
> > > > > The most striking effect is the ability to better retain a
> > > > > drag. Although the statement was made in light of possible
> > > > > (1-strong,1-weak) packets, it should help in the 2-weak case too.
> > > > 
> > > > The bigger question is why is this needed in kernel. The original
> > > > hysteresis with BTN_TOUCH was done for sole benefit of mousedev so that
> > > > we could allow somewhat better transition from standard PS/2 mode into
> > > > native Synaptics mode with absolute coordinates at time when barely
> > > > anyone had Synaptics X driver installed. This was, what, 10 years ago?
> > > 
> > > The semi-mt behavior is obviously a special case, where userspace
> > > relies on the reported number of fingers to transition between one
> > > touch and two touches. There is no pressure information sent to
> > > userspace in this case, so the situation is in fact quite similar to
> > > the ancient mousedev situation.
> > 
> > We still report ABS_PRESSURE but maybe we should report ABS_MT_PRESSURE
> > as well?
> 
> BTW, the reason I do not like this in kernel is because it dos not allow
> users control touchpad sensitivity.

...which is perfectly reasonable, I agree. OTOH, the semi-mt devices
tend to report close-to-bogus information for anything related to
individual touches. Pressure is sadly no different, as Daniel pointed
out. I don't know what is the lesser evil here.

Henrik