Controlling the Brightness of an External Monitor under Linux

At home I use an external Monitor (AOC U27P2CA) that is connected via a USB-C cable to my Laptop running PopOS 22.04 on Wayland.
I regularly change the monitor brightness depending on whether its dark outside or not.
This requires me navigating through several submenus and is quite inconvenient.

Using ddccontrl and some custom Shortcuts I can change the brightness directly from the keyboard of my Laptop.

There exist alternatives like ddcutil, those however did not work for me.

I followed the installation instructions provided in the README.
For PopOS 22.04, which is based on Ubuntu those are the following:

Installing

Install the packages:

sudo apt install ddccontrol gddccontrol ddccontrol-db i2c-tools

Restart the system.

The monitor communicates with the Laptop over i2c protocol. Add your user to the i2c group and make sure that i2c-dev kernel module is loaded:

sudo adduser $USER i2c
sudo /bin/sh -c 'echo i2c-dev >> /etc/modules'

Launch the graphical utility.

gddccontrol

The utility detected my monitor as dev/i2c-15 (yours may differ) however could not control it. It stated that my monitor was not in the data base.

Communicating with the monitor via the CLI however worked:
Reading the current brightness level can be done via this command. On my machine it also runs without sudo

ddccontrol -r 0x10 dev:/dev/i2c-15

Setting a brightness level (e.g to 75 %) is done like so:

ddccontrol -r 0x10 -w 75 dev:/dev/i2c-15

Using a capital W it is also possible to increase/decrease the brightness by a specific amount, e.g. 10 %:

ddccontrol -r 0x10 -W +10 dev:/dev/i2c-15
ddccontrol -r 0x10 -W -10 dev:/dev/i2c-15

Changing the brightness via keyboard shortcuts

In the Gnome Keyboard Settings it is possible to define commands that are run upon a custom keyboard short cut.
I defined two custom shortcuts: one for increasing the brightness level by 10 percent points, and a second for decreasing the brightness level by 10 percent points, see the following screenshot:

Controlling the Brightness of an External Monitor under Linux.png

I used F5 and F6 since they are used to change the brightness (of the Laptop display), just the modifier key is different.

I now can change the brightness of the external monitor from the keyboard of my Laptop.