SUMMARY STEPS TO REPRODUCE 1. Login to your account 2. Experience super slow login 3. After looking in the logs what's the issue, powerdevil seems to take long time to start due to timeout with dccutil execution OBSERVED RESULT Login after password successful takes around 15seconds to get to the fully functional desktop Result of the command $ time systemctl --user restart plasma-powerdevil.service real 0m12,568s user 0m0,000s sys 0m0,004s EXPECTED RESULT Login in 2 seconds SOFTWARE/OS VERSIONS Linux/KDE Plasma: Kubuntu 25.04 KDE Plasma Version: 6.3.4 KDE Frameworks Version: 6.12.0 Qt Version: 6.8.3 ADDITIONAL INFORMATION Summary KDE Powerdevil service takes 13+ seconds to start instead of <1 second, causing significant login delays after a recent libddcutil upgrade in Kubuntu 25.04. Environment OS: Kubuntu 25.04 (Plucky Pufferfish) KDE Plasma: 6.3.4 Powerdevil: 4:6.3.4-0ubuntu1 libddcutil: 2.2.0-1 (upgraded from libddcutil4 1.4.1-1build2) Hardware: AMD Ryzen 9 5900X, AMD RX 6700 XT (16GB VRAM) Monitors: 2x ASUS ROG displays via DisplayPort ASUS ROG PG278QR (2016, Week 43) ASUS ROG PG279Q (2016, Week 2) Timeline of Issue October 7, 2024: Initial installation with libddcutil4 1.4.1 - working normally July 6, 2025: libddcutil4 removed during system update - problems began July 22, 2025: Investigation revealed the regression Problem Description After the July 6, 2025 update that removed libddcutil4 and later installation of libddcutil5 2.2.0-1, powerdevil consistently takes 13+ seconds to initialize, causing significant delays during login. Root Cause Analysis Powerdevil service logs show libddcutil spending excessive time communicating with monitors via DDC/CI: jui 22 08:20:53 mauro-amd org_kde_powerdevil[2723]: Starting libddcutil. library built Feb 22 2025 at 15:37:45 jui 22 08:20:53 mauro-amd org_kde_powerdevil[2723]: Initializing libddcutil. ddcutil version: 2.2.0-dev jui 22 08:20:55 mauro-amd org_kde_powerdevil[2723]: busno=9, sleep-multiplier= 2,00, Testing for unsupported feature 0xdd returned Error_Info[DDCRC_RETRIES jui 22 08:20:55 mauro-amd org_kde_powerdevil[2723]: Turning off dynamic sleep and retrying jui 22 08:20:56 mauro-amd org_kde_powerdevil[2723]: busno=9, sleep-multiplier = 1,00, Retesting for unsupported feature 0xdd [...pattern repeats for ~13 seconds across bus 9 and 10...] jui 22 08:21:06 mauro-amd org_kde_powerdevil[2723]: Library initialization complete. Performance Comparison DDC/CI detection times: HDMI connection: 1.6 seconds (normal) DisplayPort connection: 6.7+ seconds (problematic) Manual ddcutil testing: $ ddcutil detect --sleep-multiplier 0.3 --disable-dynamic-sleep Display 1 I2C bus: /dev/i2c-9 DRM connector: card1-DP-1 Model: ROG PG278QR [Completes in ~3 seconds] Display 2 I2C bus: /dev/i2c-10 DRM connector: card1-DP-2 Model: ROG PG279Q [Completes in ~3 seconds] System Logs Evidence Package change history: $ grep "ddcutil" /var/log/dpkg.log* /var/log/dpkg.log:2025-07-06 09:10:36 remove libddcutil4:amd64 1.4.1-1build2 <none> /var/log/dpkg.log:2025-07-06 09:10:36 status not-installed libddcutil4:amd64 <none> /var/log/dpkg.log:2025-07-22 09:55:26 install ddcutil:amd64 <none> 2.2.0-1 Current package versions: $ dpkg -l | grep -E "(ddcutil|powerdevil)" ii ddcutil 2.2.0-1 amd64 Control monitor settings ii libddcutil5:amd64 2.2.0-1 amd64 Control monitor settings - shared library ii libpowerdevilcore2:amd64 4:6.3.4-0ubuntu1 amd64 shared library for KDE power management ii powerdevil 4:6.3.4-0ubuntu1 amd64 KDE power management service for Plasma I/O errors in system logs: jui 22 10:35:17 mauro-amd fwupd[7971]: failed to add device card1-DP-1/drm_dp_aux0: failed to read device firmware header: failed to write 7 bytes to 14: Erreur d'entree/sortie jui 22 10:35:17 mauro-amd fwupd[7971]: failed to add device card1-DP-2/drm_dp_aux1: failed to read device firmware header: failed to write 7 bytes to 14: Erreur d'entree/sortie Analysis and Evidence Hardware is not the issue: Identical symptoms appearing simultaneously on two different monitor models with different manufacturing dates is statistically improbable DisplayPort vs HDMI: DDC/CI works significantly faster on HDMI than DisplayPort for the same monitors Regression timing: Problem correlates precisely with libddcutil4 → libddcutil5 upgrade Version evidence: libddcutil5 2.2.0-1 is a development version (2.2.0-dev) with apparent regressions Attempted Solutions The following configuration attempts had no effect on powerdevil startup time: Environment variables: POWERDEVIL_NO_DDC=1, DDCUTIL_SLEEP_MULTIPLIER=0.3 ddcutil configuration files: /etc/ddcutil/ddcutilrc with optimized parameters Systemd service overrides: Custom environment variables in service configuration Wrapper scripts: Custom powerdevil executable wrapper with environment settings Reproduction Steps Install Kubuntu 25.04 with libddcutil5 2.2.0-1 Connect multiple DisplayPort monitors (eventually older models from 2016-2017) Observe powerdevil startup time: time systemctl --user restart plasma-powerdevil.service Compare with HDMI connection on same monitors Significant user experience degradation during login (13+ second delays) No workaround available through configuration
I forgot to mention that all controls on the 2 screens works flawlessly and without lag, color temperature from the KDE Plasma settings, brightness from the taskbar widget, ... Everything is applied on the flight and i can see it in the OSD menus of the 2 screens.
I’ve been experiencing the same issue repeatedly in the past. However, after the latest system update (with ddcutil still at version 2.2.0-1), this problem no longer seems to reproduce on my Arch Linux laptop. Perhaps this issue is also related to other packages? Below is the package update log. [2025-07-27T14:36:29+0800] [ALPM] upgraded alsa-card-profiles (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded libpipewire (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded lib32-libpipewire (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded pipewire (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded lib32-pipewire (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded libdeflate (1.23-1 -> 1.24-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded libdovi (3.3.1-1 -> 3.3.2-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded libnvme (1.14-1 -> 1.15-1) [2025-07-27T14:36:29+0800] [ALPM] upgraded linux-cachyos (6.15.7-2 -> 6.15.8-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded linux-cachyos-headers (6.15.7-2 -> 6.15.8-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded luajit (2.1.1748459687-1 -> 2.1.1753364724-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded pipewire-audio (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded pipewire-session-manager (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded pipewire-jack (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded pipewire-pulse (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded pulse-native-provider (1:1.4.6-1 -> 1:1.4.7-1) [2025-07-27T14:36:30+0800] [ALPM] upgraded qt6-base (6.9.1-4 -> 6.9.1-5) [2025-07-27T14:36:31+0800] [ALPM] upgraded telegram-desktop (5.16.4-1 -> 5.16.6-1) [2025-07-25T20:25:50+0800] [ALPM] upgraded bash (5.3.0-1 -> 5.3.3-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded ca-certificates-mozilla (3.113.1-1 -> 3.114-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded fastfetch (2.48.0-1 -> 2.48.1-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded nspr (4.36-1 -> 4.37-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded nss (3.113.1-1 -> 3.114-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded pixman (0.46.2-1 -> 0.46.4-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded libopenmpt (0.8.1-1 -> 0.8.2-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded firefox (140.0.4-1 -> 141.0-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded firefox-i18n-zh-cn (140.0.4-1 -> 141.0-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded gettext (0.25.1-1 -> 0.26-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded hmcl (3.6.14-2 -> 3.6.15-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded less (1:668-1 -> 1:679-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded lib32-glibc (2.41+r48+g5cb575ca9a3d-1 -> 2.41+r65+ge7c419a29575-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded lib32-libx11 (1.8.12-1 -> 1.8.12-2) [2025-07-25T20:25:51+0800] [ALPM] upgraded lib32-llvm-libs (1:20.1.6-1 -> 1:20.1.8-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded lib32-nspr (4.36-1 -> 4.37-1) [2025-07-25T20:25:51+0800] [ALPM] upgraded lib32-nss (3.113.1-1 -> 3.114-1) [2025-07-25T20:25:52+0800] [ALPM] upgraded linux-cachyos (6.15.7-1 -> 6.15.7-2) [2025-07-25T20:25:53+0800] [ALPM] upgraded linux-cachyos-headers (6.15.7-1 -> 6.15.7-2) [2025-07-25T20:25:53+0800] [ALPM] upgraded nodejs (24.4.1-1 -> 24.4.1-2) [2025-07-25T20:25:53+0800] [ALPM] upgraded npm (11.4.2-1 -> 11.5.1-1) [2025-07-25T20:25:53+0800] [ALPM] upgraded opencv (4.12.0-1 -> 4.12.0-2) [2025-07-25T20:25:53+0800] [ALPM] upgraded phonon-qt6 (4.12.0-4 -> 4.12.0-5) [2025-07-25T20:25:53+0800] [ALPM] upgraded qt6-declarative (6.9.1-1 -> 6.9.1-2) [2025-07-25T20:25:54+0800] [ALPM] upgraded qt6-webengine (6.9.1-1 -> 6.9.1-2) [2025-07-25T20:25:54+0800] [ALPM] upgraded tevent (1:0.16.2-1 -> 1:0.17.0-1) [2025-07-25T20:25:54+0800] [ALPM] upgraded yt-dlp (2025.06.30-1 -> 2025.07.21-1) There is some information. Operating System: Arch Linux WM: KWin (Wayland) KDE Plasma Version: 6.4.3 KDE Frameworks Version: 6.16.0 Qt Version: 6.9.1 Kernel Version: 6.15.8-1-cachyos (64-bit) Graphics Platform: Wayland Processors: 12 × 12th Gen Intel® Core™ i5-12450H Graphics Processor: Intel® Graphics Display (CMN162B): 1920x1200 @ 60 Hz (as 1536x960) in 16" [Built-in] Manufacturer: LENOVO System Version: XiaoXin 16 IAH8 ddcutil version: 2.2.0-1 powerdevil version: 6.4.3-1
Here is my current report === SYSTEM INFO === No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 25.04 Release: 25.04 Codename: plucky KDE Plasma: 6.3.4 Qt: 5.15.15 Kernel: 6.14.0-24-generic === PACKAGE VERSIONS === ddcutil: 2.2.0-1 gstreamer1.0-pipewire:amd64: 1.2.7-1ubuntu5.1 kdeplasma-addons-data: 4:6.3.4-0ubuntu1 libddcutil5:amd64: 2.2.0-1 libegl-mesa0:amd64: 25.0.7-0ubuntu0.25.04.1 libegl-mesa0:i386: 25.0.7-0ubuntu0.25.04.1 libgl1-mesa-dri:amd64: 25.0.7-0ubuntu0.25.04.1 libgl1-mesa-dri:i386: 25.0.7-0ubuntu0.25.04.1 libglu1-mesa:amd64: 9.0.2-1.1build1 libglu1-mesa-dev:amd64: 9.0.2-1.1build1 libglx-mesa0:amd64: 25.0.7-0ubuntu0.25.04.1 libglx-mesa0:i386: 25.0.7-0ubuntu0.25.04.1 libkpipewire-data: 6.3.4-0ubuntu1 libkpipewire6:amd64: 6.3.4-0ubuntu1 libkpipewiredmabuf6:amd64: 6.3.4-0ubuntu1 libkpipewirerecord6:amd64: 6.3.4-0ubuntu1 libpipewire-0.3-0t64:amd64: 1.2.7-1ubuntu5.1 libpipewire-0.3-common: 1.2.7-1ubuntu5.1 libpipewire-0.3-modules:amd64: 1.2.7-1ubuntu5.1 libplasma-geolocation-interface6:amd64: 4:6.3.4-0ubuntu1 libplasma5support-data: 4:6.3.4-0ubuntu1 libplasma5support6:amd64: 4:6.3.4-0ubuntu1 libplasma6:amd64: 6.3.4-0ubuntu1 libplasmaactivities6:amd64: 6.3.4-0ubuntu1 libplasmaactivitiesstats1:amd64: 6.3.4-0ubuntu1 libplasmaquick6:amd64: 6.3.4-0ubuntu1 libpowerdevilcore2:amd64: 4:6.3.4-0ubuntu1 libreoffice-plasma: 4:25.2.4-0ubuntu0.25.04.1 mesa-libgallium:amd64: 25.0.7-0ubuntu0.25.04.1 mesa-libgallium:i386: 25.0.7-0ubuntu0.25.04.1 mesa-utils: 9.0.0-2 mesa-utils-bin:amd64: 9.0.0-2 mesa-va-drivers:amd64: 25.0.7-0ubuntu0.25.04.1 mesa-va-drivers:i386: 25.0.7-0ubuntu0.25.04.1 mesa-vdpau-drivers:amd64: 25.0.7-0ubuntu0.25.04.1 mesa-vdpau-drivers:i386: 25.0.7-0ubuntu0.25.04.1 mesa-vulkan-drivers:amd64: 25.0.7-0ubuntu0.25.04.1 mesa-vulkan-drivers:i386: 25.0.7-0ubuntu0.25.04.1 pipewire:amd64: 1.2.7-1ubuntu5.1 pipewire-bin: 1.2.7-1ubuntu5.1 pipewire-pulse: 1.2.7-1ubuntu5.1 plasma-activities-bin: 6.3.4-0ubuntu1 plasma-browser-integration: 6.3.4-0ubuntu1 plasma-calendar-addons:amd64: 4:6.3.4-0ubuntu1 plasma-dataengines-addons:amd64: 4:6.3.4-0ubuntu1 plasma-desktop: 4:6.3.4-0ubuntu1 plasma-desktop-data: 4:6.3.4-0ubuntu1 plasma-desktoptheme: 6.3.4-0ubuntu1 plasma-discover: 6.3.4-0ubuntu1 plasma-discover-backend-flatpak: 6.3.4-0ubuntu1 plasma-discover-backend-fwupd: 6.3.4-0ubuntu1 plasma-discover-backend-snap: 6.3.4-0ubuntu1 plasma-discover-common: 6.3.4-0ubuntu1 plasma-discover-notifier: 6.3.4-0ubuntu1 plasma-disks: 6.3.4-0ubuntu1 plasma-distro-release-notifier: 20241226-0ubuntu2 plasma-firewall: 6.3.4-0ubuntu1 plasma-integration: 6.3.4-0ubuntu1 plasma-nm: 4:6.3.4-0ubuntu1 plasma-pa: 4:6.3.4-0ubuntu1 plasma-systemmonitor: 6.3.4-0ubuntu1 plasma-theme-oxygen: 4:6.3.4-0ubuntu1 plasma-thunderbolt: 6.3.4-0ubuntu1 plasma-vault: 6.3.4-0ubuntu1 plasma-wallpapers-addons:amd64: 4:6.3.4-0ubuntu1 plasma-welcome: 6.3.4-0ubuntu1 plasma-widgets-addons: 4:6.3.4-0ubuntu1 plasma-workspace: 4:6.3.4-0ubuntu2 plasma-workspace-data: 4:6.3.4-0ubuntu2 plasma-workspace-wallpapers: 4:6.3.4-0ubuntu1 plasma5-integration: 6.3.4-0ubuntu1 powerdevil: 4:6.3.4-0ubuntu1 powerdevil-data: 4:6.3.4-0ubuntu1 qml6-module-org-kde-pipewire:amd64: 6.3.4-0ubuntu1 qml6-module-org-kde-plasma-plasma5support:amd64: 4:6.3.4-0ubuntu1 Could it be that dccutil 2.2.0-1 isn 't working well with my PowerDevil 6.3.4 version ?? I don't know.
Any news on this issue ?
Can you upgrade to Plasma 6.4.5 and ddcutil 2.2.1 and try again? There have been some fixed in those versions.
I need to look on how to deploy these version on my Kubuntu 25.04 as this doesn't seem to be delivered by the current update channel, i am still with Plasma 6.3.4 and ddcutil 2.2.0-dev.
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