LG Gram under Linux

90% of the machine works out of the box with a recent Debian. Wifi, USB, the SD card reader, even suspend/resume.

The model I have is the 2020 17" model; 17Z90N (which is the US not the Australian model). I've installed a 1Tb NVME drive, and am running Debian Unstable on it.

Two things amaze me: it's only around 1.3kg; and the battery lasts a long time. This without very much compromise on performance: a kernel compile (using the config below, -j 8. and gcc 10) takes around 9 minutes; I do see some thermal throttling during such a compilation.

The few things that do not work out of the box are:

• The Fingerprint reader
• the ‘reader mode’ button (Fn-F9)
• the ‘touchpad disable’ button (Fn-F5)
• The battery care setting that allows you to restrict charging to 80%
• Some thunderbolt docks do not hotplug correctly/

Apart from the fingerprint reader, all these can be fixed. Battery care needs a patch that is in kernel 5.15 --- Debian Testing And Unstable have this.

Reader Mode

1. Act on the button to reduce the colour temp
2. Update the LED on the button
3. Fix the permissions so ordinary users can do this

ACTION=="add",SUBSYSTEM=="platform", \
   RUN+="/bin/chgrp video /sys/devices/platform/lg-laptop/reader_mode"
ACTION=="add",SUBSYSTEM=="platform",\
    RUN+="/bin/chmod 0664 /sys/devices/platform/lg-laptop/reader_mode"

Put this into /etc/udev/rules.d/90-lg-platform.rules — it will make it possible for the person logged into the laptop to change the LED.

Install the sct tool (on Debian or Ubuntu, apt install sct) Create a script in ~/bin/readermode or another convenient place.

#!/bin/sh
led=/sys/devices/platform/lg-laptop/reader_mode
TOGGLE=$HOME/.toggle_readermode

if [ ! -e $TOGGLE ]
then
	> $TOGGLE
	sct 4800
	echo 1 > $led
else
	rm $TOGGLE
	echo 0 > $led
	sct
fi

Finally bind Fn-F9 to run ~/bin/readermode. I run XFCE4, and can do this from Settings->Keyboard->Application Shortcuts.

Touchpad disabling

LG provide Fn-F5 for disabling the touchpad, so you can type easily without moving the mouse all over the place.

To make it work, create a new file ~/bin/touchpad_toggle containing this:

#!/bin/sh
# This shell script is PUBLIC DOMAIN. You may do whatever you want with it.

TOGGLE=$HOME/.toggle_touchpad

ELAN=`xinput list | sed -n 's/.*ELAN0E03:00 04F3:3121.*id=\([0-9]*\).*/\1/p'`
TP=`xinput list | sed -n 's/.*ELAN0E03:00 04F3:3121 Touchpad.*id=\([0-9]*\).*/\1/p'`


if [ ! -e $TOGGLE ]; then
    touch $TOGGLE
    for x in $ELAN
    do
	xinput disable $x
    done
    echo 0 > /sys/devices/platform/lg-laptop/leds/tpad_led/brightness
    notify-send -u low -t 1000 -i mouse --icon=/usr/share/icons/HighContrast/256x256/status/touchpad-disabled.png "Trackpad disabled"
else
    rm $TOGGLE
    xinput enable $TP
    echo 1 > /sys/devices/platform/lg-laptop/leds/tpad_led/brightness
    notify-send -u low -t 1000 -i mouse --icon=/usr/share/icons/HighContrast/256x256/devices/input-touchpad.png "Trackpad enabled"
fi

Battery Care

Batteries last a lot longer if they're ony charged to 80%. LG provide a method for doing this; for recent LG Gram models, you'll have to wait for the patch. When you get a suitable kernel (5.15 or later), add

# Restrict charging to 80%
echo 80 > /sys/devices/platform/lg-laptop/battery_care_limit

[Unit]
 Description=/etc/rc.local Compatibility
 ConditionPathExists=/etc/rc.local

[Service]
 Type=forking
 ExecStart=/etc/rc.local start
 TimeoutSec=0
 StandardOutput=tty
 RemainAfterExit=yes
 SysVStartPriority=99

[Install]
WantedBy=multi-user.target

Next time you reboot, the charge will max out at 80%.

Thunderbolt Hotplug

Some docks seem to work correctly if plugged in at boot, but if they are unplugged and replugged stop working. This is because the BIOS doesn't reserve space for the PCIe hotplug registers.

To fix, add GRUB_CMDLINE_LINUX_DEFAULT="pci=assign-busses,realloc,hpbussize=0x10,hpmmiosize=128M,hpmmioprefsize=1G" to /etc/default/grub and run sudo update-grub

Other Tweaks

#!/bin/sh
# Power saving tunables
#
echo 1500 > /proc/sys/vm/dirty_writeback_centisecs
#echo '0' > /proc/sys/kernel/nmi_watchdog
# i915
echo 'auto' > '/sys/bus/i2c/devices/i2c-9/device/power/control'
# USB3 port
echo 'auto' > '/sys/bus/pci/devices/0000:00:14.0/power/control'
#Thunderbolt port
echo 'auto' > '/sys/bus/pci/devices/0000:00:07.0/power/control'
# WIFI
echo 'auto' > '/sys/bus/pci/devices/0000:00:14.3/power/control'
# SPI
echo 'auto' > '/sys/bus/pci/devices/0000:00:1f.5/power/control'
#??
echo 'auto' > '/sys/bus/pci/devices/0000:00:04.0/power/control'
# 

echo 'auto' > '/sys/bus/pci/devices/0000:00:00.0/power/control'
#
# NVME Disks
echo 'auto' > '/sys/bus/pci/devices/0000:2c:00.0/power/control';
echo 'auto' > '/sys/bus/pci/devices/0000:2c:00.0/power/control'

Kernel config

Fingerprint Reader