Ubuntu Manpage: ddcutil - Query and change monitor settings

NAME

       ddcutil - Query and change monitor settings

SYNOPSIS

       ddcutil   [--adl|-a   adapter-index.display-index]   [--async]  [--bus|-b  busno]  [--ddc]
       [--display|--dis|-d  dispno]  [--edid  256  hex  character  EDID]  [--excp]   [-f|--force]
       [--force-slave-address]   [--hiddev   hiddevdevicenumber]   [--mfg|-g  manufacturer  code]
       [--maxtries (comma-separated-list)] [--model|-l model name] [--nodetect]  [--sn|-n  serial
       number]  [  --rw  |  --ro  |  --wo]  [--show-table|--no-table]  [-s|--stats [stats-class]]
       [-t|--terse|--brief|-v|--verbose]  [-U|--show-unsupported]   [--usb|-u   busnum.devicenum]
       [--verify  |  --noverify]  [-V|--version] [h|--help] detect | capabilities | scs | probe |
       getvcp [feature-code|feature-group] |setvcp feature-code new-value ] |  vcpinfo  [feature-
       code|feature-group]   |   dumpvcp   [filename]  |  loadvcp  filename  ]  |  environment  |
       usbenvironment'| interrogate

DESCRIPTION

ddcutil is used to query and change monitor settings.

ddcutil communicates with monitors implementing MCCS (Monitor Control Command Set) using
the DDC/CI protocol on the I2C bus. Normally, the video driver for the monitor exposes
the I2C bus as devices named /dev/i2c-n. Alternatively, ddcutil can communicate with USB
connected monitors implementing the USB Monitor Control Class Specification.

The Monitor Control Command Set describes a collection of Virtual Control Panel (VCP)
features that a monitor can implement. Each feature is identified using a single byte.
For example, feature x10 is the brightness control.

In general, the monitor settings that can be controlled by ddcutil are a superset of what
can be changed using the buttons on a monitor and its on screen display. The specific
capabilities vary from monitor to monitor.

A particular use case for ddcutil 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.

Another common use case is to switch the monitor input source.

This man page includes only abbreviated documentation of trace and other program
diagnostic facilities.

For extended documentation, use the "--help" option, and see http://www.ddcutil.com.

COMMANDS

detect Report monitors

vcpinfo [ feature-code | feature-group ]
Describe VCP feature codes that ddcutil knows how to interpret

capabilities
Query the monitor's capabilities string

getvcp [ feature-code | feature-group ]
Report a single VCP feature value, or a group of feature values

setvcp [+|-] feature-code new-value
Set a single VCP feature value. If + or - is specified, it must be surrounded by
blanks, and indicates a relative value change of a Continuous VCP feature.

dumpvcp filename
Save color profile related VCP feature values in a file. If no file name is
specified, one is generated and the file is saved <describe location>

loadvcp filename
Set VCP feature values from a file. The monitor to which the values will be
applied is determined by the monitor identification stored in the file. If the
monitor is not attached, nothing happens.

environment
Probe the ddcutil installation environment.

scs Issue DDC/CI Save Current Settings request.

usbenv Probe USB aspects of the ddcutil installation environment.

probe Explore the capabilities and features of a single monitor.

interrogate
Collect maximum information for problem diagnosis.

chkusbmon
Tests if hiddev device is a USB connected monitor, for use in udev rules.

COMMAND ARGUMENTS

       feature-code

       A  feature-code  is  specified  by  its  2 character hex feature number, with or without a
       leading "0x", e.g.  0x10, 10

       feature-group

       The following are the most useful feature groups recognized.  For a  complete  list,   use
       the --help option.

       ALL|KNOWN
              All feature codes understood by ddcutil
       COLOR  Scan color related feature codes
       PROFILE
              Subset  of  color  related feature codes that are saved and restored by dumpvcp and
              loadvcp
       SCAN   Scan all possible feature codes 0x00..0xff, except those known the be write-only

       Feature group names can be abbreviated to the first 3 characters.  Case is ignored.   e.g.
       COL, pro

       new-value

       A decimal number in the range 0..255, or hexadeciaml number in the range x00..xff.

OPTIONS

Options for monitor selection. If none are of these options are specified, the default is
the first detected monitor. Options --mfg, --model and --sn can be specified together.
-d,--display
display-number logical display number (starting from 1)
-b,--bus
bus-number I2C bus number
-a,--adl adapterIndex.displayIndex
ADL adapter and display indexes
--hiddev
device number hiddev device number
-u,--usb busnum.devicenum
USB bus and device numbers
-g,--mfg
3 letter manufacturer code
-l,--model
model name
-n,--sn
serial number. (This is the "serial ascii" field from the EDID, not the binary
serial number.)
-e,--edid
256 hex character representation of the 128 byte EDID. Needless to say, this is
intended for program use.

Options to control the amount and form of output.
-t, --terse, --brief
Show brief detail. For command getvcp, the output is in machine readable form.
-v, --verbose
Show extended detail
-U, --show-unsupported
Normally, getvcp does not report unsupported features when querying a feature-
group. This option forces output.
--show-table | --no-table
Normally, getvcp does not report Table type features when querying a feature-group.
--show-table forces output. --no-table is the default.
--rw, --ro, --wo
Limit getvcp or vcpinfo output to read-write, read-only, or (for vcpinfo) write-
only features.
--mccs MCCS version
Tailor vcpinfo output to a particular MCCS version, e.g. 2.1

Options for diagnostic output.
--stats [all|errors|tries|calls|elapsed|time]
Report execution statistics. If no argument is specified, or ALL is specified,
then all statistics are output. elapsed is a synonym for time. calls implies
time.
I2C bus communication is an inherently unreliable. It is the responsibility of the
program using the bus to manage retries in case of failure. This option reports
retry counts and various performance statistics.
--ddc Reports DDC protocol errors. These may reflect I2C bus errors, or deviations by
monitors from the MCCS specification.

Options for program information.
-h,--help
Show program help.
-V, --version
Show program version.

Options to tune execution:
--maxtries (max-read-tries, max-write-read-tries, max-multi-part-tries)
Adjust the number of retries
--force-slave-address
Take control of slave addresses on the I2C bus even they are in use.
-f, --force
Do not check certain parameters.
--verify
Verify values set by setvcp or loadvcp. (default)
--noverify
Do not verify values set by setvcp or loadvcp.
--async
If there are multiple monitors, initial checks are performed in multiple threads,
improving performance.
--nodetect
If the monitor is specified by its I2C bus number (option --busno) skip the monitor
detection phase, improving performance.

EXECUTION ENVIRONMENT

       Requires       read/write       access       to       /dev/i2c        devices.         See
       http://www.ddcutil.com/i2c_permissions.

NVIDIA PROPRIETARY DRIVER

       Some  newer  Nvidia  cards (e.g. GTX660Ti) require special settings to properly enable I2C
       support.   If you are using this driver and ddcctool does not work with your  Nvidia  card
       (TODO: Describe symptoms), you can try the following:

       Copy      file      /usr/local/share/ddcutil/data/90-nvidia-i2c.conf      to     directory
       /etc/X11/xorg.conf.d

       sudo cp /usr/local/share/ddcutil/data/90-nvidia-i2c.conf /etc/X11/xorg.conf.d

       This file will work "out of the box" if you do not have an /etc/X11/xorg.conf  file.    If
       you  do,  adjust the Identifier value in the file to correspond to the value in the master
       xorg.conf file.

       (Note that the above instructions assume that datadir was  set  to  /usr/local/share  when
       ddcutil was installed.  YMMV)

       For further discussion of Nvidia driver settings, see http://www.ddcutil.com/nvidia.

AMD PRORIETARY DRIVER

       AMD's  proprietary  video  driver fglrx does not expose the I2C bus.  Instead, it provides
       access to the  bus  through  the  AMD  Display  Library,  aka  ADL.   Owing  to  copyright
       restrictions,  the  ADL  header  files  are  not  distributed  with  the  ddcutil  source.
       Additional steps are required to build ddcutil with fglrx support.

       To see if your copy of ddcutil was built with fglrx support, issue the command:
       ddcutil --version

       ADL identifies monitors using an adapter-number/display-number pair.  To select a  monitor
       using  these numbers, specify the --adl option with a period separating the adapter-number
       and display-number, e.g.
       --adl 0.1

VIRTUAL MACHINES

       Virtualized video drivers in VMWare and VirtualBox do not provide I2C emulation.   Use  of
       normal video drivers with PCI passthrough is possible.

EXAMPLES

       ddcutil detect
       Identify all attached monitors.

       ddcutil getvcp supported

       Show all settings that the default monitor supports and that ddcutil understands.

       ddctpp getvcp 10 --display 2
       Query the luminosity value of the second monitor.

       ddcutil setvcp 10 30 --bus 4
       Set the luminosity value for the monitor on bus /dev/i2c-4.

       ddcutil vcpinfo --verbose
       Show detailed information about VCP features that ddcutil understands.

       ddcutil interrogate > ~/ddcutil.out
       Collect  maximum information about monitor capabilities and the execution environment, and
       direct the output to a file.

DIAGNOSTICS

       Returns 0 on success, 1 on failure.

       Requesting help is regarded as success.

AUTHOR

       Sanford Rockowitz (rockowitz at minsoft dot com)
       Copyright 2015-2018 Sanford Rockowitz

                                          01 April 2018                                ddcutil(1)