• This widget allows you to adjust the brightness of external monitors. We accomplish that using DDC/CI, a protocol that allows your computer to control monitors and change options like the brightness or contrast.
• A seamless integration into the Plasma desktop is a major goal of this project. The widget is versatile and can be used as a standalone widget or integrated into the system tray.
• Notebook monitors are currently unsupported because they use different interfaces to communicate with the operating system.

• Python 3.8 or newer
• python library fasteners
• ddcutil 1.4.1 or newer (older versions may work but caused issues in the past)

DDC/CI communication relies on i²C busses. The i2c-dev kernel module exposes this functionality to the userspace. Most kernel builds should include this module already, so it only needs to be loaded.

Check if it is already loaded:

$ lsmod | grep i2c_dev

If it isn't, load it automatically on every boot:

$ echo i2c-dev | sudo tee /etc/modules-load.d/i2c-dev.conf

or load it once:

$ sudo modprobe i2c-dev

ddcutil is a command line utility to control external monitors. We use ddcutil to detect supported monitors and adjust their brightness. For additional details, refer to the great ddcutil documentation. Note that additional steps may be required if you are using a NVIDIA GPU, see Special Nvidia Driver Settings in the ddcutil documentation.

Install the ddcutil from your distribution's repositories. (Arch Linux)

By default, ddcutil can only be used the the root user. Little configuration is required to allow non-root users to use it:

$ sudo usermod -aG i2c <username>

If the group i2c doesn't exit, create it first:

$ sudo groupadd --system i2c

Finally, you need to install a udev rule to allow members of the group i2c to access to i²c devices:

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

Now, you can verify that ddcutil is working correctly:

$ ddcutil detect

The output should look something like that:

Display 1
   I2C bus:  /dev/i2c-9
   DRM connector:           card0-DP-1
   EDID synopsis:
      Mfg id:               DEL - Dell Inc.
      Model:                DELL S2721DGF
      Product code:         16857  (0x41d9)
      Serial number:        XXXXXXXX
      Binary serial number: XXXXXXXX (0xXXXXXXXX)
      Manufacture year:     2022,  Week: 35
   VCP version:         2.1

Display 2
   I2C bus:  /dev/i2c-10
   DRM connector:           card0-DP-2
   EDID synopsis:
      Mfg id:               DEL - Dell Inc.
      Model:                DELL U2417H
      Product code:         16615  (0x40e7)
      Serial number:        XXXXXXXX
      Binary serial number: XXXXXXXX (0xXXXXXXXX)
      Manufacture year:     2018,  Week: 22
   VCP version:         2.1

Install the backend from PyPI using the following command:

$ pip install --user ddcci-plasmoid-backend

Install the official package from the KDE store or install it directly from the repository:

$ git clone https://github.com/davidhi7/ddcci-plasmoid.git
$ cd ddcci-plasmoid
$ kpackagetool5 --install plasmoid
# or upgrade the plasmoid:
$ kpackagetool5 --upgrade plasmoid

This widget can be displayed within the system tray or as a standalone widget.

Right-click the arrow of the system tray > open settings > go to Entries > scroll down to the entry Display Brightness and set the visibility according to your preference.

Right-click your desktop > click Add widgets > search for Display Brightness and add the widget to your desktop or panels.

This is a bug in older ddcutil versions which it is fixed in ddcutil v1.4.1. In some cases, it may cause the backend to fail.

• Fix backend errors with certain NVIDIA GPUs
• Fix compatibility with Python 3.9 and 3.8

• Allow integration into the system tray (#2)
• Scrolling while hovering sliders now works (#15, thanks CatEricka)
• Add translations for Simplified Chinese (thanks CatEricka) and German (by myself)
• Lower minimum Python version to 3.8
• Add option to specify the backend executable command manually (thanks CatEricka)

• Fix error if serial number is missing (#6)

• Add padding to widget title
• Fix duplicate monitor detection (#1)
• Expand debug output

• Fix KDE widget configuration not loading

First public release