Lenovo ThinkPad T480

This article covers the installation and configuration of Arch Linux on a Lenovo T480 laptop. Everything seems to work pretty much out the box.

For a general overview of laptop-related articles and recommendations, see Laptop.

TrackPoint and Touchpad

TrackPoint and Touchpad work out of the box and do not seem to have the same issues as the X1 Carbon Gen 6.

However one could benefit from having greatly increased event reporting frequency by enabling psmouse kernel module option synaptics_intertouch=1.

This can be made permanent with:

/etc/modprobe.d/psmouse.conf

options psmouse synaptics_intertouch=1

For two-finger scrolling activity this gives a boost from 40 Hz to 135 Hz on average which is more than threefold increase. This boost greatly contributes to the Desktop environment scrolling performance and smoothness.

(evhz-git^AUR) may be of use to find out how frequently Touchpad reports events. For example after enabling said option:

# evhz

Press CTRL-C to exit.
...
^C
Average for Synaptics TM3276-022:   137Hz

Note that units adorned with the "glass Touchpad mod" will not benefit from the elevated Touchpad performance with the procedure above. Running evhz will also indicate a different Touchpad identifier:

# evhz

...
Average for Synaptics TM3625-010:    42Hz

Power management/Throttling issues

Due to missing Intel Dynamic Platform and Thermal Framework (DPTF) support for Linux, a feature which should detect whether the laptop is used on a desk or on the lap so it can throttle the CPU in the latter case to reduce the temperature is not working and the CPU is always throttled. An Lenovo employee explained the situation and the solution Lenovo is building in a PDF posted in their forum (archive.org backup of the PDF). The firmware and EFI fixes have been released for a different model and Lenovo has recognized that the T480 is affected, so there is hope the T480 will get the fix too.

An interim fix is throttled (Github).

Also see:

• Lenovo ThinkPad X1 Carbon (Gen 6)#Power management/Throttling
• Lenovo ThinkPad T480s#Thermal throttling

/usr/local/bin/throttlestop

#!/bin/bash
# Disable BD PROCHOT signal on ThinkPads to prevent throttling the CPU to min. freq.
modprobe msr
reg="$(rdmsr -d 0x1FC)"         # commands rdmsr and wrmsr provided by msr-tools on Arch
if [ $((reg%2)) -eq 1 ]; then   # basically reg & 0xFFFE
	wrmsr 0x1FC $((reg-1))
fi

Firmware

Lenovo provides firmware updates for this device through the Linux Vendor Firmware Service (LVFS).

Available updates and changelogs can be found on the LVFS website. These include security patches for the Intel Management Engine and the system firmware.

The updates can be installed using fwupd.

Screen backlight

Without the intel driver (xf86-video-intel), neither xbacklight or xrandr brightness control are working.

However, the package acpilight provides a drop-in replacement for xbacklight. Apart from installing the package (which conflicts with xorg-xbacklight), you have to add your user to the video group and add the following udev rule:

/etc/udev/rules.d/90-backlight.rules

SUBSYSTEM=="backlight", ACTION=="add", \
  RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness", \
  RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"

SUBSYSTEM=="leds", ACTION=="add", KERNEL=="*::kbd_backlight", \
  RUN+="/bin/chgrp video /sys/class/leds/%k/brightness", \
  RUN+="/bin/chmod g+w /sys/class/leds/%k/brightness"

This allows you to control the backlight with xbacklight command provided by acpilight, as well as control the various LEDs on your T480.

Encryption and keyboard

Assuming encrypted installation, during boot process you are prompted to enter password to decrypt disk. In some cases you may not be able to enter password, because at this time keyboard driver is not loaded yet.

To fix this, add the atkbd module to the mkinitcpio MODULES array:

/etc/mkinitcpio.conf

MODULES = (... atkbd)

Regenerate the initramfs afterwards.

Fingerprint reader

Install python-validity^AUR and register fingerprints with:

$ fprintd-enroll

Refer, for example, to the entry on fingerprint sensor of the similar Lenovo ThinkPad X270 for general procedures if list_devices failed is returned. You might also try referring to these steps, which are nominally for Fedora but which appear to work on Arch as well.

Function keys

Some special buttons are not supported by X server due to keycode number limit. Certain keys are also handled by other devices other than the keyboard.

1. As reported by Libinput
2. As reported by Wayland Event Viewer