ddcci

• DKMS package: ddcci-driver-linux-dkms

• DDC/CI (Display Data Channel Command Interface) can be used to communicate with external monitors implementing MCCS (Monitor Control Command Set) over I2C

• Using ddcci and i2c-dev modules simultaneously may result in resource conflicts such as a Device or resource busy error
• DDC can control brightness, contrast, inputs, etc on supported monitors
• Expose external monitors in sysfs at /sys/class/backlight/ (e.g., intel_backlight)
• Power level of backlight LEDs can be controlled using ACPI kernel module

# /etc/modules-load.d/ddcci.conf
ddcci

• Each detected DDC/CI device gets a directory in /sys/bus/ddcci/devices
• The main device on a bus is named ddcci[I²C bus number]