Display Brightness Slider for Gnome Shell

Brightness Control

1. install ddcutil

2. Manually load kernel module i2c-dev

modprobe i2c-dev

3. Verify that your monitor supports brightness control

ddcutil capabilities | grep "Feature: 10"

4. udev rule for giving group i2c RW permission on the /dev/i2c devices

sudo cp /usr/share/ddcutil/data/45-ddcutils-i2c.rules /etc/udev/rules.d

5. Create i2c group and add yourself

sudo usermod your-user-name -aG i2c

sudo groupadd --system i2c

6. load i2c-dev automatically

touch /etc/modules-load.d/i2c.conf

echo "i2c-dev" >> /etc/modules-load.d/i2c.conf

This tool uses ddcutil as backend, so first make sure that your user can use use following shell commands without root or sudo.

ddcutil getvcp 10 to check the brightness of a monitor and

ddcutil setvcp 10 100 to set the brightness to 100

It automatically supports multiple displays detected by

ddcutil detect

Issues

Screen hangs/locks on first startup

In my hardware for some reason when ddcutil detect is ran for the first time after a cold boot and then, when it checks for i2c busno=1, whole system locks for couple of seconds. As a workaround I changed this extension to read cached info from a file, when it exists.

ddcutil --brief detect > $XDG_CACHE_HOME/ddcutil_detect