linux-kernel - Re: [PATCH 01/01] Input multitouch: fix horizontal two-finger-scrolling on Sentelic touchpads

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Message-ID: <20121219230945.GA25106@sherka.no-ip.biz>
Date:	Thu, 20 Dec 2012 00:09:45 +0100
From:	Christophe TORDEUX <christophe@...deux.net>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Henrik Rydberg <rydberg@...omail.se>,
	Tai-hwa Liang <avatar@...telic.com>,
	Oskari Saarenmaa <os@...u.fi>, Paul Fox <pgf@...top.org>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	torvalds@...ux-foundation.org
Subject: Re: [PATCH 01/01] Input multitouch: fix horizontal
 two-finger-scrolling on Sentelic touchpads

From: Christophe TORDEUX <christophe@...deux.net>

Apply the following change to the Sentelic touchpad driver:
report only the position of the first finger as absolute non-MT 
coordinates, instead of reporting both fingers alternatively. Actual MT 
events are unaffected.

Signed-off-by: Christophe TORDEUX <christophe@...deux.net>
----

This is a much simpler version of my patch. Basically, it makes little 
sense to report both fingers alternatively, as long as it's non-MT 
events. With this approach, storing coordinates of the previously 
reported touch is not necessary. This patch is against kernel version 
3.7. Works with a touchpad version STL3888_C0, very probably works on 
all later version, and very probably does not impact any earlier 
version. This patch has two effects:
1) fix horizontal and improve vertical scrolling, though maybe in a
coincidental way and 2) work towards making the non-MT absolute events
a purely legacy single finger fallback mode, without breaking anything.

diff -uprN -X vanilla/linux-3.7-rc8/Documentation/dontdiff vanilla/linux-3.7/drivers/input/mouse/sentelic.c linux-3.7/drivers/input/mouse/sentelic.c
--- vanilla/linux-3.7/drivers/input/mouse/sentelic.c	2012-12-15 13:51:58.768136524 +0100
+++ linux-3.7/drivers/input/mouse/sentelic.c	2012-12-19 23:26:49.289517251 +0100
@@ -791,7 +791,7 @@ static psmouse_ret_t fsp_process_byte(st
 			fsp_set_slot(dev, 0, fgrs > 0, abs_x, abs_y);
 			fsp_set_slot(dev, 1, false, 0, 0);
 		}
-		if (fgrs > 0) {
+		if (fgrs ==1 || (fgrs == 2 && !(packet[0] & FSP_PB0_MFMC_FGR2))) {
 			input_report_abs(dev, ABS_X, abs_x);
 			input_report_abs(dev, ABS_Y, abs_y);
 		}

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