Fedora_Brightness_Automation_Buttons_OSD/README.md

Fedora Brightness Automation Buttons OSD

Small Fedora/GNOME brightness setup for laptops with an internal Linux backlight and an external DDC/CI monitor.

The internal display is the master. Brightness keys change the internal panel, show a compact OSD, and a user service mirrors the same percentage to the external monitor with ddcutil.

This avoids drift from letting two outputs auto-adjust independently.

Features

• Internal display controlled with brightnessctl
• External monitor mirrored with ddcutil VCP code 10
• Compact GTK4/libadwaita OSD for custom brightness shortcuts
• Optional Wayland top-edge positioning with gtk4-layer-shell
• systemd user service for continuous external sync
• Configurable backlight device, DDC bus, monitor model, step size, and sync interval
• Optional wluma config where only the internal display is managed

Tested Setup

• Fedora 43
• GNOME Shell 49
• Internal panel: intel_backlight
• External monitor: DDC/CI via ddcutil

Other Fedora/GNOME setups should work if brightnessctl and ddcutil can control the displays.

Dependencies

sudo dnf install -y brightnessctl ddcutil python3-gobject gtk4 libadwaita gtk4-layer-shell

gtk4-layer-shell is recommended on GNOME Wayland. Without it, GNOME may place the OSD like a normal GTK window instead of pinning it at the top edge.

If your ddcutil command needs sudo, configure passwordless sudo for the specific command you use. Example:

jan ALL=(root) NOPASSWD: /usr/bin/ddcutil

Use a stricter sudoers rule if you prefer limiting arguments.

Quick Install

git clone https://gitea.diehanis.de/Jan/Fedora_Brightness_Automation_Buttons_OSD.git
cd Fedora_Brightness_Automation_Buttons_OSD
./install.sh

The installer writes:

~/.local/bin/brightness-osd
~/.local/bin/brightness-up-all
~/.local/bin/brightness-down-all
~/.local/bin/brightness-sync-hg342pcb
~/.config/systemd/user/external-brightness-sync.service
~/.config/brightness-automation/env

Then set your GNOME custom keyboard shortcuts to:

/home/YOUR_USER/.local/bin/brightness-down-all
/home/YOUR_USER/.local/bin/brightness-up-all

Use the full path in GNOME Settings.

Configuration

Edit:

~/.config/brightness-automation/env

Default config:

BRIGHTNESS_BACKLIGHT_DEVICE="intel_backlight"
BRIGHTNESS_SYNC_BACKLIGHT="/sys/class/backlight/intel_backlight"
BRIGHTNESS_STEP="10"
BRIGHTNESS_DDCUTIL_MODEL="HG342PCB"
BRIGHTNESS_DDCUTIL_DISPLAY="1"
BRIGHTNESS_DDCUTIL_BUS="16"
BRIGHTNESS_SYNC_INTERVAL="1"
BRIGHTNESS_SYNC_MIN_PERCENT="1"
BRIGHTNESS_OSD_VISIBLE_MS="1400"

After changing DDC or sync values:

systemctl --user restart external-brightness-sync.service

Finding Your Values

Backlight device:

brightnessctl -l
ls /sys/class/backlight

External monitor:

sudo ddcutil detect
sudo ddcutil getvcp 10

If ddcutil detect reports a bus like /dev/i2c-16, set:

BRIGHTNESS_DDCUTIL_BUS="16"

wluma

If you use wluma, let it manage only the internal display. The external monitor should follow through the sync service.

Optional install of the example wluma config:

INSTALL_WLUMA_CONFIG=1 ./install.sh
systemctl --user restart wluma.service

Example config is in:

wluma/config.toml

Status

systemctl --user status external-brightness-sync.service
journalctl --user -u external-brightness-sync.service -n 50 --no-pager

Uninstall

./uninstall.sh

The uninstall script keeps ~/.config/brightness-automation/env so local settings are not destroyed.