HerHde / thinkpad_acpi

A script to disable the lap mode sensor on thinkpads. Patches the thinkpad_acpi kernel module automatically using dkms.

Linux Thinkpad Disable Lapmode

During the purchase of a recent ThinkPad, I ran into an issue where I was forced to stay on the "balanced" power-mode. This is because some ThinkPads have a small accelerometer which detects if it's on an unstable surface (e.g. a lap).

Ostensibly this is because some of these devices can get dangerously hot on the bottom during use, but personally I prefer to have control over my device and what power-mode I'm in.

This script works by downloading thinkpad_acpi from the linux kernel, compiling it, and then patching the existing kernel module.

Am I affected?

In gnome power settings you might see this:

Or, you may see this result from running the powerprofilectl command:

$ powerprofilesctl
  performance:
    Driver:     platform_profile
    Inhibited:  yes (lap-detected)

* balanced:
    Driver:     platform_profile

  power-saver:
    Driver:     platform_profile

Will this solution work for me?

Some thinkpads don't seem to respect the changes, they may have some other kernel/hardware level control, I'm not sure what causes this.

Supported Operating Systems

These are distros I have actually tested the script on.

• Fedora 34/35/36
• Ubuntu 20.04/22.04

Installation

You are replacing a kernel module, this comes with some degree of risk to your system. Please consider backing up important data before beginning.

Install prerequisites:

# RHEL (F34+)
sudo dnf update
sudo dnf install make automake gcc gcc-c++ kernel-devel dkms wget openssl

# Ubuntu (20.04+)
sudo apt-get update && sudo apt-get upgrade
sudo apt-get install build-essential dkms git

# Reboot after updates!
sudo reboot

Install module:

git clone https://github.com/JosiahBull/thinkpad_acpi
cd thinkpad_acpi

# Copy the files for dkms
sudo cp -R . /usr/src/thinkpad_acpi-1.0

# Add the module to dkms
sudo dkms add -m thinkpad_acpi/1.0

# Build the module
# !!!IMPORTANT!!! An internet connection is required for this step! A script will automatically download
# and patch files from the linux kernel. See scripts/download.sh for more information.
sudo dkms build thinkpad_acpi/1.0

# Install the module
sudo dkms install thinkpad_acpi/1.0

# Reboot to reload the kernel
sudo reboot

Upon running sudo modinfo thinkpad_acpi, you should see the version is set to:

version: 420.26
singer: DKMS module signing key

Congratulations! You've patched your kernel. The lap-mode sensor is now disabled.

Uninstallation

Uninstallation is easy, dkms should restore the original kernel module.

sudo dkms uninstall thinkpad_acpi/1.0
sudo dkms remove thinkpad_acpi/1.0
yes | sudo rm -rd /usr/src/thinkpad_acpi-1.0
sudo reboot

Other Solutions

• Monkey Patching the kernel (untested): https://blog.cloudflare.com/how-to-monkey-patch-the-linux-kernel/ Credit to @lachlan2k for finding this.

# This is a guess for possible syntax, I provide no guarantees.
probe module("thinkpad_acpi").function("lapsensor_get").return {
    *present = 1;
    *state = 1;
}

Relevant Discussions

• https://ask.fedoraproject.org/t/what-is-lap-mode/9524
• https://askubuntu.com/questions/1416465/how-to-disable-lap-detection
• https://askubuntu.com/questions/1416567/disable-lap-mode-on-lenovo-laptop
• https://www.reddit.com/r/thinkpad/comments/o2h6kf/linux_lap_mode/
• https://bugzilla.redhat.com/show_bug.cgi?id=2014261

Licensing & Contribution

All contributions are welcome, and will be licensed under MIT unless otherwise specified.