Pierre Couderc composed on 2021-07-10 23:07 (UTC+0200): > see : https://paste.debian.net/1203999/ > for( .local/share/xorg/Xorg.0.log) What does xrandr -q report booted this way?
https://wiki.archlinux.org/title/Backlight may warrant a read. I have to suspect acpi_backlight=vendor on kernel command line is not taken well by the 3840x2160 screen. Whatever caused [ 313.732] (WW) modeset(0): Option "PreferredMode" is not used I can't tell. > https://paste.debian.net/plain/1204000 [ 870.193] (EE) modeset(0): failed to set mode: Invalid argument appears multiple times quite some lines after these: [ 869.149] (II) modeset(0): Using user preference for initial modes [ 869.149] (II) modeset(0): Output eDP-1 using initial mode 1920x1080 +0+0 [ 869.149] (II) modeset(0): Output HDMI-1 using initial mode 3840x2160_30.00 +0+0 The last line indicates the screens overlap instead of side by side placement. It should end +1920+0 if everything else is OK, which pretty much explains absence of 4k screen output. Have you tried booting with a clean kernel command line, e.g. without acpi_backlight=vendor in particular? Likely dmesg and journal need to be explored to find a reason for the invalid argument errors. Adding drm.debug=0x1e & log_buf_len=1M to kernel command line may be needed to help diagnosis. I only had a 4K display for 3 weeks 3 years ago, so it's hard for me to be very helpful by trying to match behavior, or construct a configuration file free of errors. -- Evolution as taught in public schools is, like religion, based on faith, not based on science. Team OS/2 ** Reg. Linux User #211409 ** a11y rocks! Felix Miata
