Patch "Input: psmouse - disable automatic probing of BYD touchpads" has been added to the 4.8-stable tree

Patch "Input: psmouse - disable automatic probing of BYD touchpads" has been added to the 4.8-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    Input: psmouse - disable automatic probing of BYD touchpads

to the 4.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     input-psmouse-disable-automatic-probing-of-byd-touchpads.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e9fb7cc63801d3dc71b60ca11c4d08f68f879a53 Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Sat, 12 Nov 2016 10:45:48 -0800
Subject: Input: psmouse - disable automatic probing of BYD touchpads
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

commit e9fb7cc63801d3dc71b60ca11c4d08f68f879a53 upstream.

BYD automatic protocol detection is extremely unreliable and is often
triggers false positives on regular mice, Sentelic touchpads, and other
devices. BYD has several documents that have recommended detection
sequence, but they conflict with each other and, as far as I can see, still
would not produce unique enough output to reliably differentiate BYD from
other PS/2 devices.

OEMs sourcing BYD devices also do not do us any favors by not supplying any
reasonable DMI data and instead leaving turds like "To Be Filled By O.E.M."
in place of vendor data, or "System Serial Number" as serial number.

On top of that BYD is not truly modern multitouch controller, but rather a
single-touch transitional device that only reports absolute coordinates at
the beginning of finger contact and then reverts to reporting
displacements, and thus not very precise; the only benefit from using BYD
mode vs the legacy PS/2 mode is possibility of edge scrolling.

Given the above, and the fact that BYD devices are somewhat uncommon, let's
disable automatic detection of BYD devices. Users who know they have BYD
trackpads or want to experiment can attempt to activate BYD protocol via
sysfs:

	echo -n "byd" > /sys/bus/serio/devices/serio1/drvctl

Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=151691
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=175421
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=120781
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=121281
Fixes: 98ee37714493 ("Input: byd - add BYD PS/2 touchpad driver")
Reviewed-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/input/mouse/psmouse-base.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -1115,10 +1115,6 @@ static int psmouse_extensions(struct psm
 		if (psmouse_try_protocol(psmouse, PSMOUSE_TOUCHKIT_PS2,
 					 &max_proto, set_properties, true))
 			return PSMOUSE_TOUCHKIT_PS2;
-
-		if (psmouse_try_protocol(psmouse, PSMOUSE_BYD,
-					 &max_proto, set_properties, true))
-			return PSMOUSE_BYD;
 	}
 
 	/*


Patches currently in stable-queue which might be from dmitry.torokhov@gmail.com are

queue-4.8/input-change-key_data-from-0x275-to-0x277.patch
queue-4.8/input-psmouse-disable-automatic-probing-of-byd-touchpads.patch