Felix Miata composed on 2021-07-10 18:29 (UTC-0400):
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.
I forgot something important to this thread. I got a broken 55" 4K LG TV
for free 8 weeks ago. I spent $40US on parts to fix it.
I just tried connecting it to a Kaby Lake Intel PC (HD 620, not UHD 620)
via direct HDMI, along with an ordinary 1920x1080 Samsung HDTV via DisplayPort
to HDMI adapter, using openSUSE 15.2. With only the LG connected, X opened up
in 3840x2160@30 automatically. With both connected, both come up in 1920x1080@60.
However, xrandr --output HDMI-2 --primary --mode 3840x2160 --output DP-1 --mode 1920x1080 --above HDMI-2
worked a charm to set 3840x2160@30 on the LG and set the small Samsung above
the big LG.
Rebooting to Bullseye to try the same, I can't get the Samsung HDTV out of
unsupported mode, even though xrandr reports the Samsung is using its native
mode, or trying with any other supported mode selected. This smells like a
Bullseye bug waiting to be reported.
Next I tried openSUSE Tumbleweed. It works as expected there too:
# xrandr --output HDMI-2 --primary --mode 3840x2160 --output DP-1 --mode 1920x1080 --above HDMI-2
# xrandr | egrep 'onnect|creen|\*' | grep -v disconn | sort -r
Screen 0: minimum 320 x 200, current 3840 x 3240, maximum 16384 x 16384
HDMI-2 connected primary 3840x2160+0+1080 (normal left inverted right x axis y axis) 1600mm x 900mm
DP-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 160mm x 90mm
3840x2160 30.00* 25.00 24.00 29.97 23.98
1920x1080 60.00*+ 59.94 30.00 24.00 29.97 23.98
# inxi -SGay
System:
Host: ab250 Kernel: 5.12.9-1-default x86_64 bits: 64 compiler: gcc v: 11.1.1
parameters:...
Desktop: Trinity R14.0.10 tk: Qt 3.5.0 info: kicker wm: Twin 3.0 vt: 7
dm: TDM Distro: openSUSE Tumbleweed 20210611
Graphics:
Device-1: Intel HD Graphics 630 vendor: ASUSTeK driver: i915 v: kernel
bus-ID: 00:02.0 chip-ID: 8086:5912 class-ID: 0300
Display: x11 server: X.Org 1.20.11 driver: loaded: modesetting
unloaded: fbdev,vesa alternate: intel display-ID: :0 screens: 1
Screen-1: 0 s-res: 3840x3240 s-dpi: 144 s-size: 678x572mm (26.7x22.5")
s-diag: 887mm (34.9")
Monitor-1: DP-1 res: 1920x1080 hz: 60 dpi: 305 size: 160x90mm (6.3x3.5")
diag: 184mm (7.2")
Monitor-2: HDMI-2 res: 3840x2160 hz: 30 dpi: 61
size: 1600x900mm (63.0x35.4") diag: 1836mm (72.3")
OpenGL: renderer: Mesa DRI Intel HD Graphics 630 (KBL GT2)
v: 4.6 Mesa 21.1.2 compat-v: 3.0 direct render: Yes