Created attachment 136613 [details] Xorg.0.log On my 4k notebook screen I can't use 1080p or 720p resolutions anymore. It is working on an older system snapshot with kde4. Probably it broke with the newer xorg server. Original bugreport: https://bugs.kde.org/show_bug.cgi?id=388670
More likely because you switched to -modesetting and it does not provide the same fake modes by default.
The kde4 snapshot was using xf86-video-intel unlike the plasma5 snapshot which uses xf86-video-modesetting. That explaines at least the differences. "cat /sys/class/drm/card0-eDP-1/modes" returns only "3840x2160" all the other modes are somehow generated by xf86-video-modesetting. I was interrested where these modes are generated. I could not find the modelines inside the xorg code. But my guess is that the doublescan modes are derived from the CEAVideoModes in hw/xfree86/modes/xf86EdidModes.c (line 903) That would explain why these modes are really strange. Why should an "1024x768"x120.1 mode use doublescan? It was a feature for low resolution modes. For now I think it is a bug that these modes are in the list. Somethere I've read that the intel driver tries to scale any mode to the native resolution. So a really nice feature would be if the wrong fake modes could be replaced by usefull fake modes, which can be used for full screen: 1/1.5 => 2560x1440 (not native, 2x2 to 3x3 scaling) 1/2 => 1920x1080 1/3 => 1280x720 1/4 => 960x540 (questionable) Some of the 4:3 modeswould be still usefull for legacy fullscreen applications like emulators. So removing them wouldn't be a good idea.
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