From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH] Input: synaptics - Adjust threshold for treating position values as negative Date: Mon, 10 Sep 2012 14:10:13 -0700 Message-ID: <5697296.C0n5qnnV7e@dtor-d630.eng.vmware.com> References: <1347281227-20973-1-git-send-email-seth.forshee@canonical.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Return-path: Received: from mail-pb0-f46.google.com ([209.85.160.46]:42226 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751788Ab2IJVK3 (ORCPT ); Mon, 10 Sep 2012 17:10:29 -0400 Received: by pbbrr13 with SMTP id rr13so3049361pbb.19 for ; Mon, 10 Sep 2012 14:10:28 -0700 (PDT) In-Reply-To: <1347281227-20973-1-git-send-email-seth.forshee@canonical.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: Seth Forshee Cc: linux-input@vger.kernel.org, Daniel Kurtz On Monday, September 10, 2012 07:47:07 AM Seth Forshee wrote: > Commit c039450 (Input: synaptics - handle out of bounds values from the > hardware) caused any hardware reported values over 7167 to be treated as > a wrapped-around negative value. It turns out that some firmware uses > the value 8176 to indicate a finger near the edge of the touchpad whose > actual position cannot be determined. This value now gets treated as > negative, which can cause pointer jumps and broken edge scrolling on > these machines. > > I only know of one touchpad which reports negative values, and this > hardware never reports any value lower than -8 (i.e. 8184). Moving the > threshold for treating a value as negative up to 8176 should work fine > then for any hardware we currently know about, and since we're dealing > with unspecified behavior it's probably the best we can do. The special > 8176 value is also likely to result in sudden jumps in position, so > let's also clamp this to the maximum speicified value for the axis. It looks like there is another touchpad that got broken with that "out of bounds" change, see: https://bugzilla.kernel.org/show_bug.cgi?id=46371 Thanks. -- Dmitry