From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261629AbVGKLLW (ORCPT ); Mon, 11 Jul 2005 07:11:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261633AbVGKLLW (ORCPT ); Mon, 11 Jul 2005 07:11:22 -0400 Received: from gw.alcove.fr ([81.80.245.157]:25271 "EHLO smtp.fr.alcove.com") by vger.kernel.org with ESMTP id S261629AbVGKLLT convert rfc822-to-8bit (ORCPT ); Mon, 11 Jul 2005 07:11:19 -0400 Subject: Re: [PATCH] Apple USB Touchpad driver (new) From: Stelian Pop To: Vojtech Pavlik Cc: Peter Osterlund , Andrew Morton , Johannes Berg , Linux Kernel Mailing List , Frank Arnold In-Reply-To: <20050711110024.GA23333@ucw.cz> References: <20050708101731.GM18608@sd291.sivit.org> <1120821481.5065.2.camel@localhost> <20050708121005.GN18608@sd291.sivit.org> <20050709191357.GA2244@ucw.cz> <20050710120425.GC3018@ucw.cz> <1121078371.12621.36.camel@localhost.localdomain> <20050711110024.GA23333@ucw.cz> Content-Type: text/plain; charset=utf-8 Date: Mon, 11 Jul 2005 13:08:35 +0200 Message-Id: <1121080115.12627.44.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.1.1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Le lundi 11 juillet 2005 à 13:00 +0200, Vojtech Pavlik a écrit : > On Mon, Jul 11, 2005 at 12:39:31PM +0200, Stelian Pop wrote: > > > > > Using a function like > > > > > > > > return (x_old * 3 + x) / 4; > > > > > > > > eliminates the need for a FIFO, and has similar (if not better) > > > > properties to floating average, because its coefficients are > > > > [ .25 .18 .14 .10 ... ]. > > > > > > Agreed. > > > > Except that this does not work well enough. > > I guess the quick motion compensation in input bites you. The above > equation should do even more smoothing than regular 4-point floating > average. Possible. The 'fuzz' parameter in input core serves too many usages ihmo. Let me try removing the quick motion compensation and see... > > I already thought about this, one problem is that the sensors do not > > report the pressure but only the amount of surface touched. A person > > with thick fingers will always generate higher pressures then one with > > thin ones, no matter how hard they push on the touchpad. > > That's what all other touchpads do. I thought the hardware is capable of calculating real pressure... > > I don't think this value is reliable enough to be reported to the > > userspace as ABS_PRESSURE... > > I believe it'd still be more useful than a two-value (0 and 100) output. Ok, I'll do it. > > + /* > > + * in the future, we could add here code to search for > > + * a second finger... > > + * for now, scrolling using the synaptics X driver is > > + * much more simpler to achieve. > > + */ > > This could be quite useful, too, for right and middle button taps (2 and > 3 fingers) - since the Macs lack these buttons. Indeed. But this can be a later improvement, let's make one finger work for now :) Stelian. -- Stelian Pop