I2C Device Permissions

ddcutil requires read/write access to /dev/i2c devices, or more precisely those /dev/i2c devices associated with video controllers. It can, of course, be run as root.

(For USB devices, see USB Device Permissions).

Normally, ddcutil installs udev rules file 60-ddcutil-i2c.rules which uses tag uaccess to grant read/write permissions to /dev/i2c devices associated with a video controller. The file is installed in the system rules directory, /usr/lib/udev/rules.d/.

In some circumstances, such as running on a system that uses eudev instead of udev, manual configuration may be required. For details, see Granting I2C Device Permissions Using Group I2C