https://bugs.kde.org/show_bug.cgi?id=516066
--- Comment #6 from Sanfod Rockowitz <[email protected]> --- (In reply to allegedbanana+kdebugs from comment #5) > (In reply to Sanfod Rockowitz from comment #2) > > It's hard to know what to make of this report. The special Nvidia driver > > config parms are sometimes needed for I2C to work, but it's odd that the > > latest ddcutil development branch would trigger that need; perhaps it's > > triggered by increased use of /sys. I've requested additional information > > from YanEx. > > > > ddcutil issue https://github.com/rockowitz/ddcutil/issues/583 appears to be > > a permissions configuration problem on the user's nixOS system. > > > > Issues https://github.com/rockowitz/ddcutil/issues/581 and > > https://github.com/rockowitz/ddcutil/issues/582 are more critical. In > > particular, issue #581 hangs powerdevil at startup, because /dev/i2c > > permissions are lost. It appears that under certain circumstances, > > permission granted by udev token uaccess is not respected by linux api > > access(). Perhaps the problem is arch/cachos specific. I've recoded > > libddcutil to not use access(). Also reported in that issue thread was a > > display change detection hang caused when a laptop display was not enabled > > at startup and then enabled. Laptop displays don't support DDC/CI, as > > there's no point in libddcutil tracking connection changes for them, so I've > > simply disabled change detection for laptop displays. (A display reference > > for the laptop display is still reported by libddcutil, so I don't think > > this change affects powerdevil.) > > > > I've requested more information on issue #582 and haven't received a > > response. The problem appears related to VM usage. > > > > I'd very much appreciate people testing release 2.2.5 and branch 2.2.6-dev > > with powerdevil on as many distributions and hardware configurations as > > possible. I've not been able to replicate the failures. Their resolution > > is currently my top ddcutil priority. > > Hi, I am using Gentoo and have ddcutil 2.2.6 installed. I am pretty sure, > having followed the docs, that ddcutil is setup with the correct > permissions. When KDE loads, I have brightness bars in the system try applet > for both my monitors. When I scroll up or down the percentages change, but > it takes a few extra seconds for the brightness to actually adjust. > Eventually one of the bars for one of my monitors disappears and does not > come back. I am able to continue adjusting the bar that remains, but it > still always takes quite a few seconds for the changed value to kick in. > > SOFTWARE/OS VERSIONS > Operating System: Gentoo > KDE Plasma Version: 6.6.5 > KDE Frameworks Version: 6.27.0 > Qt Version: 6.11.1 > Kernel Version: Linux localhost 6.18.37-p1-gentoo-dist #1 SMP > PREEMPT_DYNAMIC Mon Jul 6 18:10:40 EDT 2026 x86_64 AMD Ryzen 7 5700G with > Radeon Graphics AuthenticAMD GNU/Linux > Graphics Platform: Wayland > Graphics Processor 1: NVIDIA GeForce 1080ti GPU > > I have also tested this on Kubuntu, and everything works fine there. Not > sure if it is a configuration issue as can often be the case with Gentoo, or > if it is ddcutil. This should probably be a separate bug report, but I'll respond here. That everything works on Kubuntu but CachyOS does suggest a CachyOS configuration problem, but it could also reflect different ddcutil and powerdevil versions. If you're seeing 3023 errors in the output of "journalctl -b -t org_kde_powerdevil", the problem, as described above, is that the monitor is reporting a different brightness value from the one sent to the monitor, which causes powerdevil to remove the slider for the monitor. The workaround is to add line "options: noverify" to the global or libddcutil section of config file $HOME/.config/ddcutil/ddcutilrc. If problems persist, please if you can build from github branch 2.2.8-dev at https://github.com/rockowitz/ddcutil. install it in /usr/local ("make install"). Add line :"options: --trace-api" to the libddcutil section of $HOME/.config/ddcutil/ddcutilrc. and restart PowerDevil. Submit the output of journalctl -b -t org_kde_powerdevil, beginning with the line "Starting libddcutil" prior to the errors. Also document the system software installed for kubuntu (where things apparently work) and (cachyos) where they don't. Also, for each environment, the output of "sudo ddcutil interrogate". I -- You are receiving this mail because: You are watching all bug changes.
