Ubuntu Manpage: ddcutil - Query and change monitor settings

NAME

       ddcutil - Query and change monitor settings

SYNOPSIS

       ddcutil  [--display|--dis|-d  dispno]  [--bus|-b  busno] [--adl|-a adapter-index.display-index] [--hiddev
       hiddevdevicenumber] [--usb|-u busnum.devicenum] [--edid 256 hex character  EDID]  [--mfg|-g  manufacturer
       code]  [--model|-l  model  name] [--sn|-n serial number] [--noverify] [-v|--verbose] [-t|--terse|--brief]
       [-U|--show-unsupported]  [--ddc]  [-s|--stats]  [--trace  trace-class]   [--timestamp|--ts]   [--maxtries
       commaseparatedlist] [--force-slave-address] [-f|--force] [--async] [--nodetect] [-V|--version] [h|--help]
       detect  |  listvcp | capabilities | getvcp | probe [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.

       For extended documentation, see http://www.ddcutil.com.

COMMANDS

       detect Report attached 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

       dumpvcp filename
              Save  color  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.

       usbenv Probe USB aspects of the ddcutil installation environment.

       probe  Explore the capabilities and features of a sing 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    All feature codes understood by ddcutil
       KNOWN  Scan all understood feature codes, but show only codes supported by the monitor
       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 number in the range 0..255

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.
-U, --show-unsupported
Normally, getvcp does not report unsupported features when querying a feature-group. This option
forces output.
-t, --terse, --brief
Show brief detail. For command getvcp, the output is in machine readable form.
-v, --verbose
Show extended detail

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.
--trace trace-class
Enable debug tracing for a trace class. Valid values are: base, i2c, adl, ddc, main, and the
special value all. Some trace classes are more useful than others.
Specify this option multiple times to enable multiple trace classes.
--timestamp, --ts
Prepend trace messages with elapsed time

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-read-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 package i2c-dev

       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)

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 in a virtual machine has not been tested.

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 2015-2016 Sanford Rockowitz

                                                15 December 2015                                      ddcutil(1)