Provided by: ddcutil_0.8.6-1_amd64 bug


       ddcutil - Query and change monitor settings


       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


       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


       detect Report attached monitors

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

              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.

              Probe the ddcutil installation environment.

       usbenv Probe USB aspects of the ddcutil installation environment.

       probe  Explore the capabilities and features of a sing monitor.

              Collect maximum information for problem diagnosis.

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



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


       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
              Subset of color related feature codes that are saved and restored  by  dumpvcp  and
       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


       A number in the range 0..255


       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.
              display-number logical display number (starting from 1)
              bus-number I2C bus number
       -a,--adl adapterIndex.displayIndex
              ADL adapter and display indexes
              device number hiddev device number
       -u,--usb busnum.devicenum
              USB bus and device numbers
              3 letter manufacturer code
              model name
              serial  number.   (This  is  the "serial ascii" field from the EDID, not the binary
              serial number.)
              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
              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.
              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
              Take control of slave addresses on the I2C bus even they are in use.
       -f, --force
              Do not check certain parameters.
              Verify values set by setvcp or loadvcp. (default)
              Do not verify values set by setvcp or loadvcp.
              If there are multiple monitors, initial checks are performed in  multiple  threads,
              improving performance.
              If the monitor is specified by its I2C bus number (option --busno) skip the monitor
              detection phase, improving performance.


       requires package i2c-dev

       i2c permissions


       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

       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'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


       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.


       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.


       Returns 0 on success, 1 on failure.

       Requesting help is regarded as success.


       The project homepage:


       Sanford Rockowitz (rockowitz at minsoft dot com)
       Copyright 2015-2016 Sanford Rockowitz

                                         15 December 2015                              ddcutil(1)