Disable ThinkPad TrackPad in Ubuntu 16.04

25 Mar 2017

Once upon a time, disabling the trackpad in the BIOS worked. That time is no more.

A bit of poking around showed me that I could use the xinput command to find my trackpad's device id like so:

$ xinput --list
⎡ Virtual core pointer                    	id=2	[master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer              	id=4	[slave  pointer  (2)]
⎜   ↳ SynPS/2 Synaptics TouchPad              	id=11	[slave  pointer  (2)]
⎜   ↳ TPPS/2 IBM TrackPoint                   	id=12	[slave  pointer  (2)]
⎣ Virtual core keyboard                   	id=3	[master keyboard (2)]
    ↳ Virtual core XTEST keyboard             	id=5	[slave  keyboard (3)]
    ↳ Power Button                            	id=6	[slave  keyboard (3)]
    ↳ Video Bus                               	id=7	[slave  keyboard (3)]
    ↳ Sleep Button                            	id=8	[slave  keyboard (3)]
    ↳ Integrated Camera                       	id=9	[slave  keyboard (3)]
    ↳ AT Translated Set 2 keyboard            	id=10	[slave  keyboard (3)]
    ↳ ThinkPad Extra Buttons                  	id=13	[slave  keyboard (3)]

So my trackpad is device 11, a Synaptics TouchPad. After some googling, I came up with this shell script:

#!/bin/bash

set -e
set -o pipefail
set -u

# We want to capture the id from this line:
# ⎜   ↳ TPPS/2 IBM TrackPoint     id=12   [slave  pointer  (2)]

DEVICE_ID=$(xinput list | grep 'TouchPad' | sed -n 's/^.*id=\([0-9]*\).*$/\1/p')
echo "TrackPoint device id is $DEVICE_ID"
# show the user the current status of the device
xinput --list-props $DEVICE_ID | grep 'Device Enabled'
echo "disabling..."
xinput --disable $DEVICE_ID
# show the user the changed status of the device
xinput --list-props $DEVICE_ID | grep 'Device Enabled'

# Apparently this also works:
# $ synclient TouchpadOff=1
# See also the docs for synclient (synaptics touchpad client)
# https://www.x.org/archive/X11R7.5/doc/man/man4/synaptics.4.html

But I wanted more. I wanted to disable the trackpad for all users, from the xorg config files. That was quite a journey.

After lots of googling and experimenting, I made a few discoveries. One is that the location of xorg conf is now spread out amongst files ending in .conf in this directory:

/usr/share/X11/xorg.conf.d

and I see that there are already two files of interest:

50-synaptics.conf

and

51-synaptics-quirks.conf

which proved to be useful for inspiration, but I left them unedited

Also useful to know is that xorg's logs are kept in

/var/log/Xorg.0.log

And as I was futzing around with differnt configs, the logs would give me some useful feedback like so:

[     8.222] (==) Using config directory: "/etc/X11/xorg.conf.d"
[     8.222] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[     8.222] Data incomplete in file /etc/X11/xorg.conf.d/99-disable-trackpad.conf
	InputDevice section "SynPS/2 Synaptics TouchPad" must have a Driver line.
[     8.222] (EE) Problem parsing the config file
[     8.222] (EE) Error parsing the config file

One important thing I found in my travels was that I did not want to use the xinput command; I wanted to use the synclient command, for my synaptics touchpad! And listing the properties from the point of vew of my synaptics client proved to be hugely useful:

$ synclient -l | sort
# output omitted ...
    TouchpadOff             = 2
# output omitted ...

Note that the value 2 means the trackpad turns itself off after typing stops, but otherwise it's on.

Another thing I discovered is that even though the system xorg config files live in this directory:

/usr/share/X11/xorg.conf.d/

my own config file could (should?) instead go in this directory, which I had to create:

# mkdir /etc/X11/xorg.conf.d

I ended up creating a file in that directory:

# mv /usr/share/X11/xorg.conf.d/90-disable-touchpad.conf /etc/X11/xorg.conf.d/

and that file's contents ended up being

Section "InputClass"
    Identifier     "SynPS/2 Synaptics TouchPad"
    MatchDriver    "synaptics"
    Option         "TouchpadOff" "1"
EndSection

And note that the exact same property, listed by synclient, is used in this xorg conf file, and I just set the value to 1 instead of 2.

Even, cooler, when I look at /var/log/Xorg.0.log, I see that the pre-existing synaptic-oriented conf files in /usr/share/X11/xorg.conf.d get applied, but then my file, with the higher number (starts with 90 instead of 50 and 51) gets applied:

[     6.702] (II) config/udev: Adding input device SynPS/2 Synaptics TouchPad (/dev/input/event5)
[     6.702] (**) SynPS/2 Synaptics TouchPad: Applying InputClass "evdev touchpad catchall"
[     6.702] (**) SynPS/2 Synaptics TouchPad: Applying InputClass "evdev touchscreen catchall"
[     6.702] (**) SynPS/2 Synaptics TouchPad: Applying InputClass "touchpad catchall"
[     6.702] (**) SynPS/2 Synaptics TouchPad: Applying InputClass "Default clickpad buttons"
[     6.702] (**) SynPS/2 Synaptics TouchPad: Applying InputClass "SynPS/2 Synaptics TouchPad"

Here are some useful links I used while trying to figure this out: