DDC Control
DDCcontrol is a software used to control monitor parameters, like brightness, contrast, RGB color levels and others.
DDCcontrol consists of:
ddccontrol - command-line tool for monitor parameters controlgddccontrol - GUI tool for monitor parameters controlDDCcontrol communicates with monitors from userspace through the Linux
i2c-dev interface (/dev/i2c-*). AMD ADL and legacy direct PCI backends have
been removed. For directly connected displays, this uses the same kernel
userspace I2C path as ddcutil; USB-connected DDC/CI displays are not supported
yet.
The most convenient way to install DDCcontrol is to use packages from official distribution repositories.
Manual installation is more complicated, but contains latest version of software and more monitor profiles.
DDCcontrol tools, ddccontrol and gddccontrol can be installed from official distribution repositories with following command:
sudo apt install ddccontrol gddccontrol ddccontrol-db i2c-toolssudo dnf install ddccontrol ddccontrol-gtksudo zypper in ddccontrol i2c-toolsYou might need to restart your system after installing i2c-tools.
For the signed Debian and Fedora repositories built from upstream releases, see package repository installation and release setup.
Building requires Rust and Cargo 1.70 or newer. The workspace declares this
minimum in Cargo.toml, and CI tests Rust 1.70.0, 1.85.0, and stable. Rust 1.70
supports the existing Option::is_some_and
use and keeps compatibility with the Rust 1.75 toolchain in the Ubuntu 24.04
build images. The Rust 1.85 toolchain
shipped in Debian 13 (trixie) meets
the minimum, including on ppc64el, riscv64, and s390x. Debian 12 (bookworm)'s
standard Rust 1.63 package is too old;
building there requires a newer toolchain. This is a source-build requirement,
not a change to the installed application's runtime requirements.
Keep Cargo.lock in format 3. Dependency updates must pass the minimum-version CI job; raising the minimum is an explicit compatibility change. The existing Rust dependencies and C ABI layouts are unchanged.
Install build dependencies:
sudo apt install intltool i2c-tools libxml2-dev libgtk3.0-dev liblzma-devsudo eopkg install -c system.develsudo eopkg install autoconf automake intltool i2c-tools m4 diffutils libtool-devel xz-devel libxml2-devel libgtk-3-develClone, build and install built version:
git clone https://github.com/ddccontrol/ddccontrol.git
cd ddccontrol
./autogen.sh
./configure --prefix=/usr/local/ --sysconfdir=/etc --libexecdir=/usr/local/lib
make
sudo make install
Monitor database is required for proper functionality. See for ddccontrol-db installation.
Run these checks before submitting Rust changes (CI uses stable for formatting and Clippy):
cargo fmt --all -- --check
cargo clippy --workspace --all-targets --all-features --locked -- -D warnings
cargo test --workspace --all-features --locked
Also run make check after building to exercise the C ABI and daemon consumers.
See the Rust migration status and plan for subsystem status,
compatibility coverage, and remaining work.
Follow the instructions on https://github.com/ddccontrol/ddccontrol-db/blob/master/doc/how-to-add-a-monitor.md for inclusion. It often merely involves adapting a few standard capabilities as many pull requests show.
gddccontrol is a graphical utility for monitor configuration. It is called Monitor Settings in list of applications.
DDCcontrol needs readable and writable /dev/i2c-* devices. Most
distributions provide this through the i2c-dev kernel module and an i2c
group. Following configuration is needed to allow a non-root user to use
gddccontrol:
sudo adduser $USER i2c
sudo /bin/sh -c 'echo i2c-dev >> /etc/modules'
Utility can launched directly from commandline:
sudo gddccontrol
gddccontrol uses standard GTK3 widgets and follows the configured GTK theme.
To try the GTK high-contrast dark theme for one launch, run:
GTK_THEME=HighContrastInverse gddccontrol
If you need to run gddccontrol through sudo, preserve the theme override
with env:
sudo env GTK_THEME=HighContrastInverse gddccontrol
For GNOME Shell top-bar menu control, see the example extension in
contrib/gnome-shell-extension.
ddccontrol allows monitor configuration directly from commandline. To probe I2C devices to find monitor buses use:
sudo ddccontrol -p
To read value of control 0x10 (brightness on VESA compliant monitors) for device dev:/dev/i2c-4:
sudo ddccontrol -r 0x10 dev:/dev/i2c-4
To set value of control 0x10 (brightness on VESA compliant monitors) to 75 for device dev:/dev/i2c-4:
sudo ddccontrol -r 0x10 -w 75 dev:/dev/i2c-4
# Save current monitor settings to non-volatile memory (if supported)
sudo ddccontrol -r 0x10 -w 75 -s dev:/dev/i2c-4
See ddccontrol -h for more information.
The NVIDIA proprietary driver sometimes fails to expose /dev/i2c-* devices for
DDC/CI communication, causing ddccontrol -p to find no monitors (or to return
I2C errors) when connected via DisplayPort or HDMI.
The fix is to add an Xorg configuration snippet that enables software I2C in the
NVIDIA driver. A ready-made configuration file is shipped with DDCcontrol at
$(datadir)/ddccontrol/90-nvidia-i2c.conf (typically
/usr/share/ddccontrol/90-nvidia-i2c.conf after installation). Copy it into
place and restart your X session:
sudo cp /usr/share/ddccontrol/90-nvidia-i2c.conf /etc/X11/xorg.conf.d/
If you built from source without installing, you can copy the file directly from the source tree:
sudo cp data/90-nvidia-i2c.conf /etc/X11/xorg.conf.d/
After restarting X, ddccontrol -p should detect your monitors normally.
See the NVIDIA developer forum thread for background on this issue.
The project is licensed under GNU General Public License v2.0 license. See COPYING for details.
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