ddcutil
From Gentoo Wiki
ddcutil is a Linux program for managing monitor settings, such as brightness, color levels, and input source. Generally speaking, any setting that can be changed by pressing buttons on the monitor can be modified by ddcutil.
Installation
USE flags
USE flags for app-misc/ddcutil Program for querying and changing monitor settings
X
|
Add support for X11 |
drm
|
Use x11-libs/libdrm for more verbose diagnostics. |
introspection
|
Add support for GObject based introspection |
usb-monitor
|
Adds support for monitors attached via USB. |
user-permissions
|
Adds a udev rules to allow non-root users in the i2c group to access the /dev/i2c-* devices. If usb-monitor is selected, users will need to be added to the video group to access the USB monitor. Otherwise, only root will be able to use ddcutil. |
Emerge
root #
emerge --ask app-misc/ddcutil
Configuration
I2C
Module i2c_dev should be loaded to allow ddcutil to work.
root #
echo "i2c_dev" > /etc/modules-load.d/i2c_dev.conf
root #
modprobe i2c_dev
Permissions
Granting I2C Device Permissions on Versions Prior to 1.4.0:
It is necessary is to add users who will use ddcutil to group i2c
root #
groupadd --system i2c
root #
modprobe i2c_dev
Create udev rule for giving group i2c RW permission on the /dev/i2c devices
root #
cp -v /usr/share/ddcutil/data/45-ddcutil-i2c.rules /etc/udev/rules.d