Message-ID: <4CFD2E15.50105@canonical.com>
Date: Mon, 06 Dec 2010 10:40:21 -0800
From: Chase Douglas <chase.douglas@canonical.com>
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To: Henrik Rydberg <rydberg@euromail.se>
CC: Dmitry Torokhov <dmitry.torokhov@gmail.com>, Jiri Kosina <jkosina@suse.cz>,
        Ping Cheng <pingc@wacom.com>, Chris Bagwell <chris@cnpbagwell.com>,
        Peter Hutterer <peter.hutterer@who-t.net>, linux-input@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] input: mt: Move tracking and pointer emulation to
 input-mt (rev2)
References: <1291224069-11770-1-git-send-email-rydberg@euromail.se>
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On 12/01/2010 09:21 AM, Henrik Rydberg wrote:
> The drivers using the type B protocol all report tracking information
> the same way. The contact id is semantically equivalent to
> ABS_MT_SLOT, and the handling of ABS_MT_TRACKING_ID only complicates
> the driver. The situation can be improved upon by providing a common
> pointer emulation code, thereby removing the need for the tracking id
> in the driver.  This patch moves all tracking event handling over to
> the input core, simplifying both the existing drivers and the ones
> currently in preparation.

When two or more fingers are down, one of the fingers controls
ABS_{X,Y}. I think the aim is to emulate current behavior for
synaptics-style touchpads, which average the position in firmware. Thus,
we should be averaging the touch positions to generate the ABS_{X,Y} values.

-- Chase
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