linux-kernel - [4.12 regression] Thinkpad X250 Touchpad and Trackpoint not recognized anymore; commit e839ffa: "Input: synaptics

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Date:   Fri, 19 May 2017 20:46:16 +0200
From:   Pascal Wichmann <pascal.wichmann@...w.de>
To:     Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [4.12 regression] Thinkpad X250 Touchpad and Trackpoint not
 recognized anymore; commit e839ffa: "Input: synaptics - add support for
 Intertouch devices"

Hello,

using the latest 4.12-rc1 kernel, the trackpoint and touchpad of my
Thinkpad X250 are not recognized.

This is caused by commit
e839ffa  Input: synaptics - add support for Intertouch devices

The specific problem seems to be the detection of whether to use
synaptics_intertouch for the psmouse module or not. That parameter
is set to -1 by default, in which case synaptics_intertouch is
enabled on my device.

When I explicitly set that parameter to 0, the trackpoint and touchpad
are recognized and work as expected.

Removing my device from smbus_pnp_ids in 4.12 rc1 fixes the issue
without need to manually disable synaptics_intertouch in the psmouse
module:

diff -ruN a/drivers/input/mouse/synaptics.c
b/drivers/input/mouse/synaptics.c
--- a/drivers/input/mouse/synaptics.c	2017-05-19 19:31:48.930734395 +0200
+++ b/drivers/input/mouse/synaptics.c	2017-05-19 19:32:00.490782484 +0200
@@ -170,7 +170,6 @@
 static const char * const smbus_pnp_ids[] = {
 	/* all of the topbuttonpad_pnp_ids are valid, we just add some extras */
 	"LEN0048", /* X1 Carbon 3 */
-	"LEN0046", /* X250 */
 	"LEN004a", /* W541 */
 	"LEN200f", /* T450s */
 	NULL

Is the ThinkPad X250 not supporting intertouch or is there another
problem causing the input devices not to work with it enabled?

Regards,
Pascal

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