ddcutil

Announcements

05 April 2021

ddcutil release 1.1.0 contains the following changes of general interest:

  • Configuration file ddcutilrc, located on the XDG config path (normally $HOME/.config/ddcutil/ddcutilrc) is processed by both ddcutil and libddcutil.
  • Monitor capabilities strings are cached to improve performance of the capabilities command.
  • Partial workarounds for problems in DRM video drivers (e.g. i915, AMDGPU) when monitors are connected to a docking station. The monitor may not be detected (because no EDID is reported), or the monitor may appear as two different /dev/i2c devices.
  • When probing /dev/i2c devices for monitors, ddcutil could put AMD Navi2 devices (e.g. RX6000 series) into an inconsistent state. This is because the driver exposes an I2C device for the SMU. Display detection is modified to avoid probing these devices.

The interface exposed by shared library libddcutil is unchanged. Its SONAME remains "libddcutil.so.4", and the package name is libddcutil4.

For a complete list of ddcutil changes and bug fixes, see Release Notes.

Prior announcements can be found here.

Introduction

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.

ddcutil primarily uses DDC/CI (Display Data Channel Command Interface) to communicate with monitors implementing MCCS (Monitor Control Command Set) over I2C. Normally, the video driver for the monitor exposes the I2C channel as devices named /dev/i2c-n. Alternatively, there is support for monitors (such as Eizo ColorEdge displays) that implement MCCS using a USB connection. See USB Connected Monitors.

A particular use case for ddcutil, and the one that inspired its development, is as part of color profile management. Monitor calibration is relative to the monitor color settings currently in effect, e.g. red gain. ddcutil allows color related settings to be saved at the time a monitor is calibrated, and then restored when the calibration is applied.

Restrictions:

  • ddcutil does not support laptop displays, which are controlled using a special API, not I2C.
  • Generally speaking, ddcutil can be built in a virtual machine, but will not run in a VM. This is because the virtual video drivers do not implement I2C. However, if the VM is connected to a separate video card and is running a non-virtualized driver for the card in passthru mode, then ddcutil will work.
  • Nvidia's proprietary video driver may require special configuration. See Special Nvidia Driver Settings.
  • Reading and writing Table type features is implemented but untested. See Table Features

ddcutil is released under the GNU Public License, V2 (GPLV2). The source is hosted on Github.

General support questions are best directed to the issue tracker on Github. Use of that forum allows everyone to benefit from individual questions and ideas. For details, see Technical Support.

ddcui

ddcui is a graphical user interface to ddcutil, built using Qt. It is currently beta level code. For further information, see ddcui Overview.

ddcui is released under the GNU Public License, V2 (GPLV2). The source is hosted on Github.

ddcui questions should also be directed the to the ddcutil issue tracker on Github.

Topics

Using ddcutil:

Commands and Options: - Detailed command and option documentation(command_detail.md)

Installation and Configuration:

Other:

Author

Sanford Rockowitz rockowitz@minsoft.com