https://bugs.kde.org/show_bug.cgi?id=494522
--- Comment #19 from Devin Lin <espi...@gmail.com> --- (In reply to Jakob Petsovits from comment #18) > (In reply to Devin Lin from comment #17) > > I did some line-by-line digging into the source code, apparently Powerdevil > > for some reason sets the display brightness when Plasma starts, which causes > > the monitor to crash. The status returned though is DDCRC_OK. After the > > monitor comes back online, powerdevil sets the brightness again, which > > causes the monitor to crash again... > > This is presumably KWin/Wayland integration, which sets brightness to its > stored value for the monitor (currently defaulting to 1.0 if none is stored) > when PowerDevil announces the monitor's brightness controls to KWin. It also > sets the brightness value again on any output configuration change. If the > monitor disappears but then re-appears again, PowerDevil will announce it > again to KWin and the cycle continues. > > Thanks for digging. This is another data point (perhaps the biggest one) > that we need to be able to disable hardware brightness controls per monitor. > > Could you also check if setting brightness manually with ddcutil (`ddcutil > --display=<which> setvcp 10 50`) will also cause the monitor to crash? Indeed, running `ddcutil --display=1 setvcp 10 50` causes the display to crash after a fresh reboot of the monitor. Interestingly enough, it prints `Display not found` It is inconsistent though in that if you change some settings (ex. setting the refresh rate) and then run the command, it doesn't crash anymore, but instead fails with: `Verification failed for feature 10` -- You are receiving this mail because: You are watching all bug changes.
