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[2.1.5] 2024-11-01

General

Added

  • Support DisplayLink devices
  • Add command noop, which allows for executing options such as --settings without having to execute a real command.
  • As an aid to development, the build date and time are normally embedded in the ddcutil and libddcutil executables. This is reported using command **ddcutil --version --verbose". libddcutil reports this to the system log. If reproducible builds are required, use configure option --disable-build-timestamp. (For reproducible builds, building typically is performed using a script or build system, so it's not inconvenient to specify --disable-build-timestamp in this situation.)

Changed

  • User Defined Features:
    • Add XNC (Extended Non-Continous) like simple NC, but the SH byte is also reported.
    • Allow SNC (Simple Non-Continuous) as alternative name for NC.
    • Report user defined features as part of parsed capabilities.
    • Commands recognizing user defined features now fail if there's an error loading a user defined feature file. These are capabilities, setvcp, dumpvcp, and probe.
  • /usr/lib/udev/rules.d/60-ddcutil-i2c-rules:
    • Give logged on user r/w access to /dev/dri/cardN, needed to allow logged on user to probe connectors using DRM.
  • Do not install /usr/lib/udev/rules.d/60-ddcutil-usb.rules, delete it if previously installed. Addresses issues #405, #428, #437
  • Command ddcutil chkusbmon:
    • Skip processing and always return 1 (failure) if option --disable-usb is in effect.
  • Command detect:
    • Only show communication error detail if --verbose
    • Provide a clearer message if slave address x37 is inactive:
      • "Monitor does not support DDC" instead of generic "DDC_commnication failed"
      • If option --verbose is in effect, emit an additional message to check the monitor's OSD.
  • Parser changes:
    • Add alternative option names for symmetry with other options:
      • --discard-capabilities-cache is an alias for --discard-cache capabilities
      • --discard-sleep-cache is an alias for --discard cache dsa
      • --discard-dsa-cache is an alias for --discard cache dsa
    • Eliminate --enable-dsa-cache as alias for --enable-dynamic-sleep-cache
    • Improve handling of --verify/--noverify, error if both specified
  • File .gitignore:
    • Add: *.tar.gz, docs/ddcutil-c-api
  • Commands interrogate and environment --verbose:
    • Force settings --disable-cross-instance-locking, --disable-dynamic-sleep (VERIFY)
    • Forced settings apply to environment --verbose as well as interrogate
    • When probing DRM, recognize bus types DRM_BUS_PLATFORM, DRM_BUS_HOST1X, report as "platform", "host1x"
  • Change the system log message level when sleep time is adjusted from WARNING to VERBOSE. Addresses issue #427: Adjusting multiplier message fills system log when libddcutil used by clightd
  • Configuration file ddcutilrc: If there is a pound sign "#" on a line, the remainder of the line is treated as a comment.
  • Add -Wformat-security to compiler options. Addresses issue #458.
  • If option --bus specified, only check accessability for that bus, avoiding irrelevant warning messages regarding other buses. Addresses issue #461.

Fixed

  • Rework laptop detection. A non-laptop display can have an eDP connector. This is an i915 video driver bug that will not be fixed. See freedesktop.org issue "DRM connector for external monitor has name card1-eDP-1" https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/10389
  • When processing environment variable user $XDG_DATA_DIRS, or $XDG_CONFIG_DIRS,
    the final directory in the list was ignored. Issue #438
  • When processing a user defined feature file, recognize any whitespace character (e.g. tab), not just space.
  • Fix core dump on ddcutil getvcp. Issue #407
  • Commands interrogate and environment --verbose
    • Simple getvcp test was not reporting the bytes of the response packet.
    • If no device with class x03 was found, the user's home directory was dumped. Issue #413.
  • Fix display not found on Raspberry Pi. Do not rely on /sys/class/drm to read EDID, which is not valid for some drivers. Addresses issue #403
  • User Define Features file: fix error msg when nothing follow VALUE
  • Convert CRLF line endings to LF
  • Use printf() formats %jd and %zd to portably print variables of type ssize_t, time_t, so as to build unchanged on architectures such as armel, armhf.
  • Avoid compiler warning possible depending on compiler configuration when a switch() construct is used. Replaced with if/else if/else. Resolves issue #458.
  • Memory leaks.

Building

  • Re-enable autoconf/configure option --enable-x11/--disable-x11. X11 specific code is used in display change detection. the default is --enable-x11.
    Use x11 code to test for sleep mode instead of using /sys, which is unreliable for nvidia driver.

Shared Library

The shared library libddcutil is backwardly compatible with the one in ddcutil 2.1.0. The SONAME is unchanged as libddcutil.so.5. The released library file is libddcutil.so.5.1.3.

Changed

  • ddca_start_watch_displays():
    • The only event class that can currently be enabled is DDCA_EVENT_CLASS_DISPLAY_CONNECTION. Watching for sleep state changes is not currently supported.
    • Regards DDCA_EVENT_CLASS_ALL as same as DDCA_EVENT_CLASS_DISPLAY_CONNECTION
    • Error if either DDCA_EVENT_CLASS_DPMS or DDCA_EVENT_CLASS_NONE are specified.
  • Status code DDCRC_INVALID_CONFIG_FILE renamed to more general DDCRC_CONFIG_ERROR. DDCRC_INVALID_CONFIG_FILE is a valid alias.
  • Write build date and time to system log when starting libddcutil.
  • Rework libdccutil output to avoid duplicate msgs in system log when all terminal output is directed to the log, as with KDE Plasma
  • Most functions that specify a display ref now return status code DDCRC_DISCONNECTED if the display reference is no longer valid.
  • Quiesce the API during ddca_redetect_displays(). Operations that access display state are not permitted, and return DDCRC_QUIESCED.
  • Add DDCA_STATS_API to enum DDCA_Stats_Type, for reporting API specific stats.
  • Compile using option -Wformat-security. Issue #458.
  • Include thread id in messages written to syslog.

Fixed

  • ddca_start_watch_displays(): Fixed segfault that occured with driver nvidia when checking if all video adapters implement drm. Issue #390.
  • Ignore phantom displays when searching for a display reference. Issue #412.
  • ddca_get_display_refs(), ddca_get_display_info_list2() always return 0, even if an error occured when examining a particular monitor. Addresses issue #417.
    • Errors that occur opening individual displays or reading their EDIDs are are still reported using ddca_get_error_detail(). In addition, error messages are written to the terminal and, depending on the current syslog level, to the system log.
  • Display reference validation: Do not use dref->drm_connector, which may be invalid after hotplug. Addresses issue #418.
  • ddca_dref_repr(): Do not check that the display reference is still valid. It is meaningful to create a string representation of a display reference even if it is no longer usable. Addresses ddcui issue #55.
  • Protect hash table of open monitors to avoid a possible race condition.
  • Recover instead of abort when more than one non-removed display refs exist for the same display.
  • Use mutexes to control access to corruptable data structures.
  • Memory leaks.

Display Change Handling

  • Extensively reworked display change detection
    • improved performance using UDEV
    • use /sys to get EDID if possible
    • handle MST hub devices if driver/device allow
      • not all drivers work
    • only perform stabilization for removed display
    • not checking for asleep
  • Work around deficiencies of nvidia driver
    • The nvidia driver does not use /sys in the same way as amdgpu, i915, nouveau and probably other drm supporting drivers that are part of the Linux kernel.
      • Depending on driver version the /sys file system does not reflect display changes and does not generate udev events
    • alternate, much less efficient algorithm for nvidia
      • doesn't use udev
      • doesn't rely on /sys
      • reads EDIDs in polling loop
  • Named options affecting display change detection:
    • --watch-mode UDEV, POLL, DYNAMIC (default DYNAMIC) DYNAMIC resolves to UDEV or POLL depending on whether any display uses the nvidia driver, and for the nvidia driver depending on the driver appears to change the connector edid and status value when displays are connected or disconnected
    • --enable/disable-try-get-edid-from-sysfs (default is --enable-try-get-edid-from-sysfs)
  • Utility options affecting display change detection. Some of these will become named options, others will be removed once testing is finished.
    • --f17 do not use sysfs connector_id (default is to use it)
    • --f18 always report UDEV events
    • --f20 do not try to avoid rechecking DDC responsiveness when a display is reconnected (default is to remember prior checks)
    • --f21 always treat sysfs as unreliable for reporting display changes
    • --f22 never treat sysfs as unreliable for reporting display changes
    • --i6 watch loop sleep multiplier (multiply default watch loop settings)
    • --i7 extra stabilization milliseconds after apparent disconnection
    • --i8 explicit udev poll loop milliseconds (takes precedence over --i6)
    • --i9 explicit non-udev poll loop milllisec (takes precedence over --i6)

[2.1.4] 2024-02-17

Shared Library

  • Reinstall previously deprecated and removed ddca_create_display_ref(), allowing existing clients to build unchanged.

[2.1.3] 2024-02-07

Changed

  • Option --settings reports build options.

Fixed

  • Memory leaks

Shared Library

The shared library libddcutil is backwardly compatible with the one in ddcutil 2.1.0. The SONAME is unchanged as libddcutil.so.5. The released library file is libddcutil.so.5.1.2.

Fixed

  • Due to overly aggressive DDCA_Display_Ref validation, ddca_get_display_info() returned status DDCRC_ARG when obtaining information about an invalid display (i.e. one for which the EDID is detected but DDC communication fails). This fixes ddcui issue #55, which reported an abort if a display was invalid.
  • Checking for whether the video adapter supports DRM was consolidated. This fixes a case where all displays were reported to support DRM when that was not the case, causing incorrect display status change monitoring.

[2.1.2] 2024-01-27

General

Added

  • Option --vstats reports minimum, maximum, and average successful sleep multiplier

Changed

  • Make hidden option --min-dynamic-multiplier non-hidden
  • Revert ddca_get/set_sleep_multiplier() to 2.0.0 semantics
  • Allow for the fact that the proprietary Nvidia driver always reports the value of /sys/class/drm//enabled as "disabled"

Fixed

  • Invalid assert when checking how monitor reports unsupported features. (Issue #371)
  • Segfault in environment command when examining procfs if compiled using clang option -flto (Issue #354)
  • Bring man page up to date (Issue #364)

Shared Library

The shared library libddcutil is backwardly compatible with the one in ddcutil 2.1.0. The SONAME is unchanged as libddcutil.so.5. The released library file is libddcutil.so.5.1.1.

Changed

  • ddca_start_watch_displays() requires that all video drivers support DRM. If the API call fails, detailed error information is available using ddca_get_error_detail().
  • Additional syslog messages

Fixed

  • SIGABRT in API calls that have a display reference or handle argument if ddca_init2() (or ddca_init()) had not been called. This caused KDE PowerDevil to repeatedly crash and restart.
  • Fix the check of whether all video drivers implement DRM, required for display hotplug detection.

[2.1.0] 2024-01-16

General

Added

  • Option --skip-ddc-checks
    • Skips initialization checks to confirm that DDC communication is working and the monitor properly uses the unsupported feature bit in Get Feature Reply packets, thereby improving initialization time.
  • Cross-instance locking (experimental). Uses flock() to coordinate I2C bus access to /dev/i2c devices when multiple instances of ddcutil or libddcutil are executing. Enabled by option --enable-cross-instance-locks.
  • Option --min-dynamic-multiplier Specifies a floor to how low dynamic sleep adjustment sets the sleep multiplier. (experimental)

Changed

  • Multiple "Options:" lines in an ini file segment are combined
  • Option --help:
    • Only show extended information when --verbose specified
  • Option --version:
    • Show only the version, without prefix if --brief specified
    • Include detailed build information if *--verbose specified
  • I2C bus examination during initialization can be parallelized, improving performance (This is distinct from the ddc protocol checking.) This is an experimental feature. It can be enabled by using a low value as an argument to option --i2c-init-async-min, e.g. --i2c-init-async-min 4. THIS OPTION IS DISABLED BY DEFAULT AS IT OCCASIONALLY TRIGGERS A BUG IN DRIVER amdgpu THAT CAN CAUSE THE MOUSE AND KEYBOARD TO BECOME UNRESPONSIVE. See freedesktop.org bug report "lockup in dce_i2c_submit_command_hw" at https://gitlab.freedesktop.org/drm/amd/-/issues.
  • Command detect: better messages when laptop display detected
    • do not report "DDC communication failed"
    • report "Is laptop display" instead of "Is eDP device" or "Is LVDS device"
  • Better accomodate the variation in use of sysfs by different drivers
  • Turned off unconditional message that reported an elusive Nvidia/i2c-dev driver compatibility error. The incompatibility has been full diagnosed as being caused by use of a legacy proprietary Nvidia driver. A message is still written to the system log.
  • Make more extensive use of the system log.
  • Options --enable-displays-cache, --disable-displays-cache are marked hidden since displays caching is not a released feature.
  • Deprecate vaguely named option --force. Replace its single use with
    option --permit-unknown-feature.
  • Deprecate vaguely named option --async. Use --ddc-checks-async-min
  • Deprecate vaguely named option --ddc. Use option --ddcdata, which more clearly indicates that it causes DDC data errors to be reported.
  • configure option --enable-asan causes libasan to be linked into binaries
  • configure option --enable-x11 is deprecated. The X11 API is no longer used.

Fixed

  • Better handling of DDC Null Message recognition and adjustments
  • Dynamic sleep: make it easier to reduce time - once high didn't come down
  • Command detect: ensure output of model name, serial number, and extra display descriptor use only ASCII character in the range 0..127.
  • Some USB-only code was not iftested out when configure option --disable-usb was set. (Issue 355)
  • Always set sleep multiplier to at least 1.0 for commands setvcp and scs. Addresses reports that aggressive optimization caused setvcp to fail.
  • Cross-thread locking handles situtations where a display ref does not yet exist, e.g. reading EDID.
  • Memory leaks.

Shared library

The shared library libddcutil is backwardly compatible with the one in ddcutil 2.0.0. The SONAME is unchanged as libddcutil.so.5. The released library file is libddcutil.so.5.1.0.

Added

  • Implemented display hotplug event detection
    • Requires DRM video drivers (e.g. amdgpu, i915)
    • Can detect physical connection/disconnection and DPMS sleep status chanes, but the effect of turning a monitor on or off is monitor dependant and cannot reliably be detected.
    • Enabled by libddcutil option --enable-watch-displays, or API call ddca_enable_start_watch_displays()
    • API uses callbacks to report report status changes to client
    • new status codes possible for many current API functions: DDCRC_DISCONNECTED, DDCRC_DPMS_ASLEEP
    • When a display connection event is reported, the client should call ddca_redetect_displays()
  • ddca_validate_display_ref(): Exposes the validation that occurs on any API call that has a DDCA_Display_Ref argument. Can be used to check whether a monitor asleep, disconnected, etc.
  • New functions for sleep multiplier control:
    • **ddca_enable_dynamic_sleep()
    • **ddca_disable_dynamic_sleep()
    • **ddca_get_current_sleep_multiplier()
    • **ddca_set_display_sleep_multiplier()
  • ddca_init2() replaces ddca_init(), which is deprecated: Has an additional argument for collecting informational msgs. Allows for not issuing information messages regarding the assembly of options and parsing directly from libddcutil to the terminal (now enabled by setting flag DDCA_INIT_OPTIONS_ENABLE_INIT_MSGS), but instead gives client complete control as to what to do with the messages.

Changed

  • Functions that depend on initialization and that return a status code now return DDCRC_UNINITIALIZED if ddca_init() failed.
  • Revert ddca_get_sleep_multiplier(), ddca_set_sleep_multiplier() to their pre 2.0 semantics changing the multiplier on the current thread. However, these functions are marked as deprecated.

Fixed

  • Argument passing on ddca_get_any_vcp_value_using_implicit_type()
  • Fixed cause of assert() failure in ddca_init() when the libopts string argument has a value and the configuration file is enabled but no options are obtained from the configuation file.
  • Contents of the libopts arg were added twice to the string passed to the libddcutil parser.

[2.0.0] 2023-09-25

Release 2.0.0 contains extensive changes. Shared library libddcutil is not backwards compatible.

Added

  • Install /usr/lib/modules-load.d/ddcutil.conf. Ensures that driver i2c-dev is loaded.
  • Install file /usr/share/udev/rules.d/60-ddcutil-i2c.rules, autmatically granting the logged on user read/write access to /dev/i2c devices for video displays. For most configurations, use of group i2c is no longer necessary.
  • Command options not of interest to general users are now hidden when help is requested. Option --hh exposes them, and implies option --help.
  • Option --noconfig. Do not process the configuration file.
  • Option --verbose. If specified on the command line, the options obtained from the configuration file are reported.
  • Added utility options --f7, --f8, --i2, --s1, --s2, --s3, --s4, --fl1, --fl2 These options are for temporary use during development. The current use of the utility options is reported by option --settings.
  • Added utility command C1 for temporary use during development.
  • Added option --enable-mock-data for testing
  • Option --trcfrom. Traces the call stack starting with the specified function. This option applies only to functions for which tracing has been enabled.
  • API performance profiling
  • Added options --ignore-hiddev and --ignore-usb-vid-pid
  • Added: Sample file nvidia-i2c.conf that can be installed in directory /etc/modprobe.d to set options sometimes needed by the proprieatry NVidia video driver.
  • Added option --discard-cache to discard cached data at the start of program execution. Valid arguments are capabilities, dsa, and all.
  • Command discard [capabilites|dsa|all] cache(s) discards cached data.
  • Option --pid (alt --process-id) prepends the process id to trace messages.
  • Command traceable-functions* lists functions that can be traced by name, i.e. ones that can be specified as a --trcfunc argument.
  • If using X11, terminate immediately if a DPMS sleep mode is active.

Changed

  • The dynamic sleep algorithm has been completely rewritten to both dynamically increase the sleep-multiplier factor (as needed) and decrease the sleep multiplier factor (insofar as possible). Data is maintained across program executions in file $HOME/.cache/ddcutil/stats. Option -dsa, or one of its variants such as --enable-dsa turn it on.
  • Option --sleep-multiplier: 0 is now allowed as an argument. Some DisplayPort monitors have been observed to work with this value.
  • Writing to the system log has been generalized. Option --syslog controls what is written to the system log. Recognized levels are NEVER, ERROR, WARN, INFO, and DEBUG. This option replaces --enable-syslog, --disable-syslog, and --trace-to-syslog.
  • environment --verbose: Option --quickenv skips some slow tests such as use of program i2cdetect.
  • environment --verbose: extended sysfs scan for ARM SOC devices to explore how those devices use /sys
  • Detailed statistics are now maintained on a per-display instead of per-thread basis.
  • Option --vstats includes per-display statistics in its reports. It takes the same arguments as --stats.
  • Cached capabilities are not erased by ddcutil calls that are not executed with --enable-capabilities-cache. This makes the behavior the same as cached displays and cached performance statistics.
  • environment --verbose disables caching, reports contents of cached files.
  • loosen criteria for when to try fallback methods to read EDID when using USB to communicate with Eizo monitors
  • udev rule changes:
    • install /usr/lib/udev/rules.d/60-ddcutil-usb.rules
    • rename /usr/lib/udev/rules.d/60-ddcutil.rules to 60-ddcutil-i2c.rules
    • update and rename sample rules files installed in /usr/share/data/ddcutil as 60-ddcutil-i2c.rules and 60-ddcutil-usb.rules. The user can modify these files and install them in /etc/udev/rules.d to override the files installed in /usr/lib/udev/rules.d.
  • --enable-dsa is a valid synonym for --enable-dynamic-sleep
  • Display detection improved
    • Rework the algorithm for detecting display communication and testing how invalid features are reported.
    • Handle the phantom monitor case where a MST capabile monitor is detected as a separeate i2c bus/drm connector along with that on the video card
  • Command detect improved:
    • verbose output:
      • Reports the sysfs DRM values for dpms, enabled, and status
      • Reports if I2C slave address x37 is responsive
    • reports an error summary if DDC communication fails
    • Issue warnings that output may be inaccurate if the monitor is sleeping or if it cannot be determined how unsupported features are indicated.
  • Messages regarding DDC data errors (controlled by option --ddc) are written to the system log with level LOG_WARNING instead of LOG_NOTICE.

Fixed

  • More robust checks during display detection to test for misuse of the DDC Null Message and all zero getvcp response to indicate unsupported features.
  • Option --help: Document ELAPSED as a recognized statistics class
  • ddca_dfr_check_by_dref(): do not return an error if no user defined feature file exists for the monitor
  • Recognize (but always report failure for) CHKUSBMON command even when ddcutil not built with USB support.
  • Improve reporting of /dev/hiddev* open failures to reduce confusion caused by this typically benign error.
  • Check that no display identifier is included on commands that don't use one
  • Increase buffer size to allow for a Get Feature Reply packet that contains an incorrectly large length field.
  • Change the USB infomation shown for option --version to emphasize that ddcutil uses USB for communicating with the monitor's Virtual Control Pandl, not for video transmission.
  • Memory leaks

Shared library changes

The shared library libddcutil in is not backwardly compatible.
The SONAME is now libddcutil.so.5. The released library file is libddcutil.so.5.0.0.

Library initialization has been reworked extensively to move operations that can fail and other aspects that should be under control of the library user into a new function ddca_init().

This function:

  • controls the level of messages written to the system log
  • optionally processes options obtained from the ddcutil configuration file
  • processes additional options passed as a string
  • sets error information for ddca_get_error_detail()

If this function is not called by the user program, any API function that relies on its processing invokes ddca_init() using arguments such that it never fails, e.g. the configuration file is not processed.

Added typedef

  • struct DDCA_Display_Detection_Report

Added functions:

  • ddca_init() See above.
  • ddca_register_display_detection_callback(): Registers a function of type DDCA_Display_Status_Func which will be called to inform the client of display hotplug events.
  • ddca_library_filename(): Returns the fully qualified name of the shared library.

Changed functions:

  • ddca_report_display_info() returns DDCA_Status instead of void
  • ddca_get_feature_name() implementation restored

Changed semantics:

The semantics of some functions have changed, reflecting the fact that some statistics are now maintained on a per-display rather than per-thread basis.

  • ddca_set_sleep_multiplier(), ddca_get_sleep_multiplier(). Instead of operating on the current thread, these functions operate on the display, if any, open in the current thread.

  • ddca_set_default_sleep_multiplier(), ddca_get_default_sleep_multiplier() Operate on newly detected displays, not new threads.

Removed functions:

With the ability to configure libddcutil operation both by the ddcutil configuration file and by passing an option string in the ddca_init() arguments, several API functions are no longer needed and have been removed:

Max-tries options:

  • ddca_max_max_tries()
  • ddca_get_max_tries()
  • ddca_set_max_tries()
  • ddca_set_default_sleep_multiplier(), ddca_set_global_sleep_multiplier()
  • ddca_get_default_sleep_multiplier(), ddca_set_global_sleep_multiplier()

Trace options:

  • ddca_add_traced_function()
  • ddca_add_traced_file()
  • ddca_set_trace_groups()
  • ddca_add_trace_groups()
  • ddca_trace_group_name_to_value()
  • ddca_set_trace_options()

USB enablement:

  • ddca_enable_usb_display_detection
  • ddca_disable_usb_display_detection

Miscellaneous:

  • ddca_enable_force_slave_adress()
  • ddca_is_force_slave_address_enabled()
  • ddca_enable_error_info()

Most per-thread statistics are now instead maintained on a per-display basis. The following functions are no longer useful and have been removed

  • ddca_set_thread_description()
  • ddca_append_thread_description()
  • ddca_get_thread_desription()

Remove previously deprecated functions:

  • ddca_open_display(). Use ddca_open_display2().
  • ddca_create_display_ref(). Use ddca_get_display_ref()
  • ddca_free_display_ref(). Had become a NO-OP. All display references are persistent

Symbols for functions and enums that had previously been removed from ddcutil_c_api.h are no longer exported.

Options that apply only to libddcutil (Specified in the ddcutil configuration file or passed to ddca_init())

  • Option --profile-api. Applies only to libddcutil. Statistics for API functions that perform display IO are collected and subsequently reported when the library is terminated.

  • Option --trcapi. Trace the call stack for a specified API function.

Building ddcutil

  • configure options --enable-syslog/--disable-syslog have been eliminated.
    Use runtime option --syslog NEVER to disable all writes to the system log.
  • Use of shared library libkmod eliminated.
  • Shared library libjansson is now required

[1.4.5] 2023-09-18

Building ddcutil

  • The autotools configure command now recognizes --enable-install-lib-only. If specified, command make install only installs the shared library. This is intended to facilitate installation of libddcutil.so.4 along with the upcoming libddcutil.so.5.

[1.4.2] 2023-02-17

Added

  • ddcutil installation installs files /usr/lib/modules-load.d/ddcutil.conf and /usr/lib/modules-load.d#libddcutil.conf to ensure that kernel module i2c-dev is loaded at boot time if it is not built into the kernel. There are two files so that when split up into distribution packages, each of the command line ddcutil package and the shared library libddcutil package installs a file.

[1.4.1] 2023-01-16

Fixed

  • The default sleep-multipler value was 0, instead of 1. This resulted in failure of most DDC/CI operations, including display detection.

[1.4.0] 2023-01-04

Added

  • ddcutil installation installs file /usr/lib/udev/rules.c/60-ddcutil.rules. This udev rule uses tag uaccess to give the logged on user read/write access to /dev/i2c devices associated with video adapters. Configuring use of group i2c is no longer necessary.
  • configure options --enable-syslog and --disable-syslog control whether messages are written to the system log. The default is enabled.

Changed

  • The ability to use the write()/read() interface of i2c-dev has been restored. It is needed to work around a bug in the proprietary Nvidia driver. By default, ioctl() interface is used for all drivers. If the Nvidia bug is detected, the write()/read() interface is used instead. Command line options --use-file-io and --use-ioctl-io affect this default behavior. When i2c-dev's file io interface is used, option --force-slave-address is again meaningful.
  • Option --sleep-multiplier and API functions ddca_set_sleep_multiplier_value(), ddca_set_default_sleep_multiplier_value() now accept 0 as a valid argument.
  • The ddcutil command parser reports an error if a display selection option (e.g. --bus) is given on a command to which it does not apply.
  • Write additional error and information messages to the system log.
  • Eliminate message "Is DDC/CI enabled in the monitor's on-screen display?" It's rarely the cause of communication failures.

Fixed

  • Warn of a possibly invalid DRM connector name in detect output if monitors with identical EDIDs are used with the proprietary nvidia driver.
  • Handle /dev/i2c device names with a double hyphen, e.g. /dev/i2c--3.
  • Better libddcutil handling of configuration file errors. Do not abort initialization in case of errors.
  • Fix interpretation of digital display type bits for EDID version 1.4
  • Miscellaneous segfaults.

[1.3.2] 2022-09-04

Changed

  • Modify tarball creation to eliminate garbage and otherwise unneeded files.

[1.3.0] 2022-07-19

Added

  • Command detect:
    • Issue warning for monitors for which ddcutil should not be used to change settings.
      • Currently only entry is Xaomi model "Mi Monitor"
  • Debug messages. Environment variables DDCUTIL_DEBUG_PARSE, DDCUTIL_DEBUG_MAIN, DDCUTIL_DEBUG_LIBINIT can be set to enable trace messages in command line ddcutil or shared library libddcutil.so during initialization and before command options.

Changed

  • Option --force-slave-address no longer has any effect. The dev-i2c ioctl() interface is now used exclusively instead of write() and read() calls for writing to and reading from the I2C bus. As a result, ioctl(SLAVE_ADDRESS), which has been the source of EBUSY errors from driver i2-dev, is no longer used. In principle, EBUSY errors are still possible from within individual video drivers, but this has never been observed.
  • Sleeps immediately after opening a /dev/i2c device and after completion of a read operation are completely eliminated. The sleep-suppression related uptions, --sleep-less, ***--less-sleep, --enable-sleep-suppression, and --disable-sleep-suppression no longer have any effect.
  • Option --dca: The Dynamic Sleep Adjustment algorithm was rewritten to more sensibly increment sleep times after before each retry.
  • Commands getvcp and vcpinfo:
    • Allow specification of multiple feature codes, for example ddcutil getvcp 10 12 , ddcutil vcpinfo 14 16 18 1a
  • Command detect:
    • Option --verbose produces addtional information:
    • The product code is reported in hex as well as decimal
    • The EDID source field is set to I2C in the normal case where the EDID is read directly from slave address X50. Alternative values include USB, X11, and SYSFS.
  • Command environment:
    • Scanning of /sys by option --verbose has been improved.
    • Add msg re SYSENV_QUICK_TEST environment variable
  • Command interrogate:
    • Set --disable-capabilities-cache
  • More user friendly messages at startup regarding /dev/i2c buses that cannont be opened. If the problem is inadequate permissions (EACCES), the user is directed to www.ddcutil.com/permissions.
  • Better handle malformed EDIDs
    • Trailing blanks on model and serial number are stripped. This affects commands detect --terse, loadvcp and dumpvcp, and also the file names of user defined features.
  • Option --stats:
    • I2C ioctl() calls for reading and writing are now reported as type IE_IOCTL_WRITE and IE_IOCTL_READ rather than IE_OTHER
    • IE_WRITE_READ stats are no longer reported, as they are redundant
  • Source code has been extensively cleaned up. In particular, directory adl containing code for the old proprietary AMD video driver, has been removed.
  • Building ddcutil:
    • Library libi2c.so is no longer linked. It was needed only for some experimental code. libddcutil:
  • ddca_get_display_refs(), ddca_get_display_info_list2():
    • Open errors can be retrieved using ddca_get_error_info(). Note that the API calls still succeed.
    • Deprecated API functions have no effect:
      • ddca_enable_force_slave_address(), ddca_is_force_slave_address_enabled()

Fixed

  • The sleep multiplier value was not respected for new API threads.
  • User Defined Features: Keyword NC set the incorrect flag in a feature descriptor.
  • Option --dsa: Fix adjustment factor calculation due to incorrect variable type.
  • Fixed a segfault that occurred at ddcui startup. The fault was in a trace message for function ddc_start_watch_displays() which watches for displays that are added or removed.
  • Fixed a segfault in ddcutil initialization because of unexpected contents in sysfs.
  • Do not use glib function g_byte_array_steal(), which requires glib 2.60. ddcutil requires only glib 2.40.
  • Miscellaneous memory leaks
  • Double count I2C writes in stats.

[1.2.2] 2022-01-22

Added

  • API function ddca_enable_force_slave_address()
  • API function ddca_is_force_slave_address_enabled()

Changed

  • Improve handling of and messages regarding DDC communication failures with errno EBUSY. In particular, this error occurs when driver ddcci is loaded.
    • Command detect: If DDC communication fails with error EBUSY, report the display as "Busy" instead of "Invalid" and suggest use of option --force-slave-address.
    • Command environment: Suggest use of option --force-slave-address if driver ddcci is detected.
    • Messages re EBUSY errors are always written to the system log.
  • Command detect:
    • Do not report the EDID source unless there is a value to show. This value is set only for USB connected monitors.
    • Show extended output based on option --verbose, not undocumented option --very-verbose.
    • Report color bit depth if EDID version >= 1.4
  • Command environment: Simplify the exploration of sysfs.
  • API changes:
    • Field latest_sl_values in struct DDCA_Feature_Metadata struct is no longer set,
    • API function ddca_report_display_info(): include binary serial number
  • Building and porting:
    • When building ddcutil, allow for building a static library if configure option --enable-static is set. Linux distributions frown on packaging static libraries, but if a user wants to build it who am I to judge. By default, static libraries are not built,
    • Replace use of Linux specific function __assert_fail() with exit() in traced assertions. __assert_fail is used in the Linux implementation of assert(), but is not in the C specification. This can present a problem in porting ddcutil.
  • Code cleanup:
    • Delete incomplete, experimental code for asynhronous feature access, including files src/ddc/ddc_async.c/h.
    • Remove unused files src/util/output_sink.c/h.

Fixed

  • Only write Starting/Terminating messages to the system log if option --syslog is specified.
  • Avoid compilation warnings when assert() statments are disabled (NDEBUG is defined).
  • Fixed a segfault in the debug/trace code of ddca_get_display_refs()
  • Memory leaks.

[1.2.1] 2021-11-15

Added

  • Option --syslog: Send trace and debug messages to the system log in addition to the trace location.
  • Option --wall-timestamp, --wts: Prefix trace and debug messages with the current wall time.
  • Option --settings: Report option settings in effect.

Changed

  • Details of current settings are no longer reported by every command invocation when option --verbose is specified. Use option --settings to control option reporting.
  • Removed sample program demo_watch_displays.

Fixed

  • Numerous memory leaks, in particular ones triggered by ddca_redetect_displays().
  • Build failure if configure option --enable-x11=no was specified.
  • API functions ddc_open_display(),ddc_open_display2() now always return DDCRC_ALREADY_OPEN if the the display is already open in the current thread. Previously an assert() failure would occur under certain circumstances.
  • Options --disable-capabilities-cache, --disable-udf not respected
  • Proof of concept code that watches for display hotplug events

[1.2.0] 2021-09-28

Added

  • libddcutil log file
  • libddcuti and ddcutil write critical events to syslog
  • API function ddca_add_trace_group()
  • API function ddca_extended_version_string()
  • API function ddca_redetect_displays()
  • API function ddca_get_display_refs()
  • API function ddca_get_display_info()
  • API function ddca_free_display_info()
  • Macro DDCUTIL_VSUFFIX

Changed

  • If possible, command ddcutil environment --verbose calls get-edid|parse-edid as an additional EDID check.
  • Additional validation of DDCA_Display_Ref and DDCA_Display_Handle arguments to API functions
  • Improved tracing of assert() failures
  • --enable-capabilities-cache is now the default
  • libddcutil name is now libddcutil.so.4.1.0
  • Command detect: improved analysis of /sys
  • Command detect: --verbose option reports raw EDID
  • Option --help does not report undocumented option --very-verbose.

Fixed

  • Incorrect assembly of sysfs path definitions in ddcutil environment --verbose
  • ddcutil diagnostics were not finding module i2c-dev if the system (e.g. NixOS) used a non-standard location for the modules directory (Issue #178). The checks have been rewritten to use libkmod.
  • Eliminate repeated messages from the experimental display hotplug detection code if no /sys/class/drm/cardN devices exist. (libddcutil)

[1.1.0] 2021-04-05

For details, see ddcutil Release Notes.

Added

  • Configuration file ddcutilrc, located on the XDG config path.
  • Cache monitor capabilities strings to improve performance of the capabilities command.
    Controlled by options --enable-capabilities-cache, --disable-capabilities-cache.
  • Workarounds for problems in DRM video drivers (e.g. i915, AMDGPU) when displays are connected to a docking station. The same monitor can appear as two different /dev/i2c devices, but only one supports DDC/CI. If possible these are reported as a "Phantom Display" instead of as "Invalid Display". Also, try to work around problems reading the EDID on these monitors, which can cause the monitor to not be detected.
  • Option --edid-read-size 128 or --edid-read-size 256 forces ddcutil to request that number of bytes when reading the EDID, which can occasionally allow the EDID to be read successfully.
  • Issue warning at startup if driver i2c-dev is neither loaded nor built into the kernel.

Changed

  • By default, files generated by dumpvcp are saved in the XDG_DATA_HOME directory.
  • environment --verbose has more detailed reporting of relevant sections of /sys.
  • Additional information on detect --verbose.
  • Additional functions are traceable using option --trcfunc
  • User defined features are enabled by default.

Fixed

  • Regard IO operations setting errno EBUSY as recoverable, suggest use of option --force-slave-address. (EBUSY can occur when ddcontrol's ddcci driver is loaded.)
  • Fix build failure when configure option --disable-usb is combined with --enable-envcmds.
  • On AMD Navi2 variants, e.g. RX 6000 series, ddcutil display detection put the GPU into an inconsistent state when probing a SMU I2C bus exposed by the GPU. This change ensures that ddcutil does not attempt to probe such buses.