Post-Installation Checklist

This page outlines steps that may be required to configure ddcutil after it has been installed.

Kernel Module i2c-dev

ddcutil requires kernel module i2c-dev. If it is not built into your kernel, it must be loaded explicly. Normally (as of ddcutil 1.4) this will be configured by installation of ddcutil or some other program that requires the kernel module. Otherwise, you will need to configure it yourself. For details, see Kernel Module Configuration.

Note: i2c-dev can also be written i2c_dev. The two are interchangable.

I2C Device Permissions

Permissions must be granted in order for users other than root to run ddcutil.

For details, see I2C Device Permissions.

USB Device Permissions

For situations where ddcutil needs to communication with a monitor that uses USB for communication with its virtual control panel, and wish to run ddcutil as a non-root user. you need to manually install a suitable rules file in directory /etc/udev/rules.d. A udev file for this purpose, 60-ddcutil-usb.rules can be found, after normal ddcutil installation, in directory /usr/share/ddcutil/data/60-ddcutil-usb.rules. It can also be found in the source tree in directory data/usr/lib/udev/rules.d.

Proprietary Nvidia Driver

The proprietary Nvidia video driver sometimes requires special settings for I2C communication. See Special Nvidia Driver Settings.

Configuration Diagnostics

If ddcutil installs successfully but execution fails, command ddcutil environment can be used to probe the I2C environment and may provide clues as to the problem. For USB connected monitors, use command ddcutil usbenvironment. See Secondary Commands.

Linux command i2cdetect (found in required package i2ctools) provides an independent check of whether the DDC slave address (X37) is active on an I2C bus.

Shared Library Configuration

When installing from source, additional configuration may be required to use shared library libddcutil if it is installed under /usr/local. See Shared Library Configuration. Note that libddcutil is NOT required to run ddcutil.