Disabling the Lenovo P14s Touchscreen

New job, new laptop, and I no longer an M1 MacBook Pro. This time around I have a Lenovo P14s, which unfortunately comes with a touchscreen. Touchscreens are terrible, so let’s disable it.

This is relatively straight-forward using udev. The first step is to identify the device we care about:

$ sudo dmesg | grep -i touchscreen
[    2.092460] input: ELAN901C:00 04F3:2EDE Touchscreen as /devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-2/i2c-ELAN901C:00/0018:04F3:2EDE.0002/input/input9

Having identfied that, we inspect the udev attributes exposed for us to match against:

$ udevadm info -a -p /sys/class/input/input9

  ...

  looking at device '/devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-2/i2c-ELAN901C:00/0018:04F3:2EDE.0002/input/input9':
    KERNEL=="input9"
    SUBSYSTEM=="input"
    DRIVER==""
    ATTR{capabilities/abs}=="3273800000000003"
    ATTR{capabilities/ev}=="1b"
    ATTR{capabilities/ff}=="0"
    ATTR{capabilities/key}=="400 0 0 0 0 0"
    ATTR{capabilities/led}=="0"
    ATTR{capabilities/msc}=="20"
    ATTR{capabilities/rel}=="0"
    ATTR{capabilities/snd}=="0"
    ATTR{capabilities/sw}=="0"
    ATTR{id/bustype}=="0018"
    ATTR{id/product}=="2ede"
    ATTR{id/vendor}=="04f3"
    ATTR{id/version}=="0100"
    ATTR{inhibited}=="0"
    ATTR{name}=="ELAN901C:00 04F3:2EDE"
    ATTR{phys}=="i2c-ELAN901C:00"
    ATTR{power/async}=="disabled"
    ATTR{power/control}=="auto"
    ATTR{power/runtime_active_kids}=="0"
    ATTR{power/runtime_active_time}=="0"
    ATTR{power/runtime_enabled}=="disabled"
    ATTR{power/runtime_status}=="unsupported"
    ATTR{power/runtime_suspended_time}=="0"
    ATTR{power/runtime_usage}=="0"
    ATTR{properties}=="2"
    ATTR{properties}=="2"

  ...

The ATTR{id/*} properties seem like a good way to constrain the match. From there, the key observation is that input devices present the inhibited attribute in sysfs, which we can frob via udev.

Using these properties we can write a udev rule to automatically inhibit the device for us when the driver is bound to the device:

$ cat /etc/udev/rules.d/99-inhibit-touchscreen.rules 
ATTR{id/bustype}=="0018", ATTR{id/product}=="2ede", ATTR{id/vendor}=="04f3", ATTR{id/version}=="0100", ATTR{inhibited}="1"