Just this week I got the newest Matebook 14 2020 AMD with the 4800H. On windows I'm using an UtechSmart USB-C hub to output 4K@60Hz to my monitor so physically I know it's possible.
Linux, however, is another story. I installed Kubuntu 20.04 LTS, but I could only boot to it (kernel 5.4 I believe) by going into recovery mode, and then selecting continue boot. Otherwise it would just hang on the Huawei logo. I installed the 5.8.15 kernel and everything seems to work fine, except I can't seem to set the display output to 60Hz, even though it's available in the settings, confirmed also by xrandr:
Screen 0: minimum 320 x 200, current 3840 x 3600, maximum 16384 x 16384
eDP connected primary 2160x1440+783+2160 (normal left inverted right x axis y axis) 296mm x 197mm
2160x1440 60.00*+
1920x1200 60.00
1920x1080 60.00
1600x1200 60.00
1680x1050 60.00
1280x1024 60.00
1440x900 60.00
1280x800 60.00
1280x720 60.00
1024x768 60.00
800x600 60.00
640x480 60.00
HDMI-A-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
DisplayPort-2 disconnected (normal left inverted right x axis y axis)
DisplayPort-3 disconnected (normal left inverted right x axis y axis)
DisplayPort-4 connected 3840x2160+0+0 (normal left inverted right x axis y axis) 600mm x 340mm
3840x2160 60.00 + 30.00*
2560x1440 59.95
1920x1080 60.00 59.94
1600x900 60.00
1280x1024 60.02
1280x800 59.81
1280x720 60.00 59.94
1024x768 60.00
800x600 60.32
720x480 60.00 59.94
640x480 60.00 59.94
However, running xrandr --output DisplayPort-4 --mode 3840x2160 --rate 60, I get xrandr: Configure crtc 1 failed.
In /var/log/Xorg.0.log I get:
[ 5400.937] (EE) AMDGPU(0): failed to set mode: No space left on device
[ 5401.094] (EE) AMDGPU(0): drmmode_do_crtc_dpms cannot get last vblank counter
[ 5401.227] (EE) AMDGPU(0): drmmode_do_crtc_dpms cannot get last vblank counter
I assumed this has something to do with the amdgpu drivers, so I went ahead and downloaded the latest 20.30 version, however, I get the following error:
Loading new amdgpu-5.6.5.24-1109583 DKMS files...
Building for 5.8.15-050815-generic
Building for architecture x86_64
Building initial module for 5.8.15-050815-generic
ERROR (dkms apport): kernel package linux-headers-5.8.15-050815-generic is not supported
Error! Bad return status for module build on kernel: 5.8.15-050815-generic (x86_64)
Consult /var/lib/dkms/amdgpu/5.6.5.24-1109583/build/make.log for more information.
Just yesterday I switched to Ubuntu 20.10 with the 5.8.0 kernel, but the problem still persists. I haven't tried installing amdgpu again because it messes up my installed packages and hasn't worked so far.
