ddcutil 2.1.4 - display not found; ddcutil 1.4.1 works

[p1r473]

hey! having an issue with ddcutil 2.1.4 where it cant find my monitor Display not found interrogate.log

however, ddcutil 1.4.1 installed via debian's apt install ddcutil works fine

I compiled 2.1.4 myself as the debian version is very out of date, didnt seem to get any errors The monitor is a ELECROW 8 Inch Portable Monitor Mini HDMI LCD Display 1280x800 https://www.amazon.ca/gp/product/B08YZ2XH5T/

I tried 2.1.5-dev too and it didnt fix it

Failure retrieving DRM resources, errno=95=Operation not supported

#ddcutil
wget -O /home/pi/jansson-2.13.tar.gz https://digip.org/jansson/releases/jansson-2.13.tar.gz
tar -xzf /home/pi/jansson-2.13.tar.gz  -C /home/pi
cd /home/pi/jansson-2.13
autoreconf --force --install 
./configure
make
sudo make install

wget -O /home/pi/libusb-1.0.27.tar.bz2 https://github.com/libusb/libusb/releases/download/v1.0.27/libusb-1.0.27.tar.bz2
tar -xf /home/pi/libusb-1.0.27.tar.bz2 -C /home/pi
cd /home/pi/libusb-1.0.27
autoreconf --force --install 
./configure
make
sudo make install

wget -O /home/pi/ddcutil-2.1.4.tar.gz https://www.ddcutil.com/tarballs/ddcutil-2.1.4.tar.gz
tar -xzf /home/pi/ddcutil-2.1.4.tar.gz -C /home/pi
cd /home/pi/ddcutil-2.1.4 
autoreconf --force --install 
./configure
make
sudo make install

im controlling it with a little script which works fine on 1.4.1

#!/bin/bash

# Enable and disable HDMI output on the Raspberry Pi

is_off ()
{
    ddcutil getvcp d6 | grep "0x04" >/dev/null
}

turn_on ()
{
    output=$(ddcutil setvcp d6 01 2>&1)

    # Loop until the output does not contain the verification failed message
    while [[ $output == *"Verification failed for feature d6"* ]]; do
        sleep 1 # Wait a bit before retrying to avoid spamming the command
        output=$(ddcutil setvcp d6 01 2>&1)
    done
}

# Function to set brightness
set_brightness ()
{
    local brightness=$1

    # Check if the brightness level is an integer and within the 0-100 range
    if [[ $brightness =~ ^[0-9]+$ ]] && [[ $brightness -ge 0 && $brightness -le 100 ]]; then
        ddcutil setvcp 10 $brightness
    else
        echo "Error: Brightness level must be an integer between 0 and 100." >&2
        return 1
    fi
}

case $1 in
    off)
        ddcutil setvcp d6 04
    ;;
    on)
        if is_off
        then
            turn_on
        fi
    ;;
    status)
        if is_off
        then
            echo off
        else
            echo on
        fi
    ;;
    toggle)
        if is_off
        then
            turn_on
        else
            ddcutil setvcp d6 04 
        fi
    ;;
    set)
        set_brightness $2
    ;;
    *)
        echo "Usage: $0 on|off|toggle|status|set [brightness_level]" >&2
        exit 2
    ;;
esac

exit 0

[rockowitz]

Thank you for the report.

Apparently you are running the Debian build for the Raspberry Pi. Video driver vc4 is using DRM and /sys in non-conformat ways. See for example, the the verbose output of detect, where /sys/class/drm/card1-HDMI-A-1/enabled reports "disabled" and /sys/class/drm/card1-HDMI-A-1/status reports "disconnected".

ddcutil 2.1.x makes increasing use of /sys so that libddcutil can detect dynamic display connection and disconnection, which is why you're seeing the errors. Unfortunately, this use will have to be reviewed to avoid the errors you are seeing while retaining functionality for drivers that do properly use DRM and /sys.

[p1r473]

Ok let me know if you'd like me to test a fix when you are able to

[rockowitz]

@p1r473 I've made a couple changes that reduce the use of /sysfs for video drivers that may not use /sys properly. Let me know if they address your problem.

[p1r473]

@rockowitz Its working sometimes but I am also getting mostly error output ddc.log

Failure retrieving DRM resources, errno=95=Operation not supported

and

Setting value failed for feature xD6, rc=DDCRC_RETRIES(-3007): maximum retries exceeded
    Try errors: DDCRC_RETRIES

However it is now sort of actually working

Also an issue with interrogate- it dumps the entire dir of my home folder. causing this massive 5mb log file

*** Extended dump of sysfs video devices for ARM architecture ***
Display devices: (class 0x03nnnn)
      dirname: missing operand
      Try 'dirname --help' for more information.
      .:
      total 166968
      drwxr-xr-x   3 pi   pi       4096 Apr 16 19:08 AAXtoMP3
      drwxr-xr-x   3 pi   pi       4096 Feb 12 15:33 absminitowerkit
      drwxr-xr-x   3 pi   pi       4096 Feb 12 15:33 Adafruit_LED_Backpack
      -rwxr-xr-x   1 pi   pi       1039 May 25  2021 adlists-deprecated.sh
      -rwxr-xr-x   1 pi   pi       2255 Dec  5 16:11 adlist-sequence.sh
      drwxr-xr-x   3 pi   pi       4096 Apr 26 15:48 almostontop
      -rwxr-xr-x   1 pi   pi        524 Jun  1  2021 android-otp-extractor.sh
      drwxr-xr-x   4 pi   pi       4096 Apr 26 17:05 ansiweather
      drwxr-xr-x   5 pi   pi       4096 May  6 15:57 archivemount
      drwxr-xr-x   7 pi   pi       4096 May  6 15:13 autojump