Adjusting trackpoint (or any pointing device) sensitivity through evdev

Recently I got myself a Thinkpad X1 Tablet Gen 3, however, unlike other Thinkpads, this model does not seem to use the usual Thinkpad kernel module which allows sensitivity to be set in sysfs.

Thanks to some inspiration from ChatGPT, I found out that it is possible to apply multiplier to the event stream by building a daemon that intercept the input events and modify it.

So here’s how you can do it:

Dependency

On Fedora, you will need python3-evdev installed

sudo dnf install python3-evdev 

Event modification script

Save this in /usr/local/bin/alter-sensitivy.py

import evdev
from evdev import InputDevice, UInput, ecodes
import time
import argparse

parser = argparse.ArgumentParser()
parser.add_argument('-d','--device', required=True)
parser.add_argument('-m','--multiplier', type=int, default=2)
parser.add_argument('-t','--trigger-threshold', type=int, default=2)

args = parser.parse_args()

# Open the input device
device = InputDevice(args.device)

# Create a virtual input device to emit the modified events
ui = UInput.from_device(device, name="ModifiedDevice")

# Loop to process incoming events
for event in device.read_loop():
    if event.type == ecodes.EV_REL and abs(event.value) > args.trigger_threshold:  # Modify only relative movement events if it above threshold
        for i in range(args.multiplier):
            print(event.value)
            ui.write_event(event)
            ui.syn()
            time.sleep(0.0005) # for smoothing out the movement

Find your device using sudo libinput list-devices and evtest [device].

Test it out. In this example I’m altering event of /dev/input/event5 input device which is my trackpoint. -m option allows you to configure how much you want to multiply the event (default is 2).

sudo python3 /usr/local/bin/alter-sensitivity.py -d /dev/input/event5 -m 5

Systemd service

Create a systemd service file in /etc/systemd/system/trackpoint-sensitivity.service (change /dev/input/event5 to your own device)

[Unit]
Description=Trackpoint Sensitivy
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/python3 /usr/local/bin/alter-sensitivity.py -d /dev/input/event5
Restart=always
User=root
Group=input
RestartSec=5

[Install]
WantedBy=multi-user.target

Start it

systemctl daemon-reload
systemctl start trackpoint-sensitivity