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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ondrej Zary <linux@rainbow-software.org>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: [PATCH 3.18 86/93] Input: i8042 - enable MUX on Sony VAIO VGN-CS series to fix touchpad
Date:   Fri,  6 Apr 2018 15:23:55 +0200
Message-Id: <20180406084228.943644700@linuxfoundation.org>
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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ondrej Zary <linux@rainbow-software.org>

commit 04bb1719c4de94700056241d4c0fe3c1413f5aff upstream.

The touch sensor buttons on Sony VAIO VGN-CS series laptops (e.g.
VGN-CS31S) are a separate PS/2 device. As the MUX is disabled for all
VAIO machines by the nomux blacklist, the data from touch sensor
buttons and touchpad are combined. The protocol used by the buttons is
probably similar to the touchpad protocol (both are Synaptics) so both
devices get enabled. The controller combines the data, creating a mess
which results in random button clicks, touchpad stopping working and
lost sync error messages:
psmouse serio1: TouchPad at isa0060/serio1/input0 lost sync at byte 4
psmouse serio1: TouchPad at isa0060/serio1/input0 lost sync at byte 1
psmouse serio1: TouchPad at isa0060/serio1/input0 lost sync at byte 1
psmouse serio1: TouchPad at isa0060/serio1/input0 lost sync at byte 1
psmouse serio1: TouchPad at isa0060/serio1/input0 lost sync at byte 1
psmouse serio1: issuing reconnect request

Add a new i8042_dmi_forcemux_table whitelist with VGN-CS.
With MUX enabled, touch sensor buttons are detected as separate device
(and left disabled as there's currently no driver), fixing all touchpad
problems.

Signed-off-by: Ondrej Zary <linux@rainbow-software.org>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/input/serio/i8042-x86ia64io.h |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

--- a/drivers/input/serio/i8042-x86ia64io.h
+++ b/drivers/input/serio/i8042-x86ia64io.h
@@ -712,6 +712,20 @@ static const struct dmi_system_id __init
 	{ }
 };
 
+static const struct dmi_system_id i8042_dmi_forcemux_table[] __initconst = {
+	{
+		/*
+		 * Sony Vaio VGN-CS series require MUX or the touch sensor
+		 * buttons will disturb touchpad operation
+		 */
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Sony Corporation"),
+			DMI_MATCH(DMI_PRODUCT_NAME, "VGN-CS"),
+		},
+	},
+	{ }
+};
+
 /*
  * Some Wistron based laptops need us to explicitly enable the 'Dritek
  * keyboard extension' to make their extra keys start generating scancodes.
@@ -1124,6 +1138,9 @@ static int __init i8042_platform_init(vo
 	if (dmi_check_system(i8042_dmi_nomux_table))
 		i8042_nomux = true;
 
+	if (dmi_check_system(i8042_dmi_forcemux_table))
+		i8042_nomux = false;
+
 	if (dmi_check_system(i8042_dmi_notimeout_table))
 		i8042_notimeout = true;