dual display scaling broken at 4k

[UV]

I have to 4k monitors.

15" on the dell xps 3840/2160/60
40" philips external BDM4065 3840/2160/30

Obviously i need different scale factors to use them properly.
This feature DOES NOT WORK.

It seems the scaling is not handled separately per monitor as the UI suggests.
The fractional scaling also does not seem to work. any change to the scaling ends seems to be rounded to full.
Which meens a compromise scale of 125% is effectively 200% on the large monitor.

I havent found any config which would make this useful.

So basically when I use the external 40" I cannot use the builtin anymore
without an external fresnell magnifier lens (which I dont have ;)

updated Ubuntu 20.04.1 LTS on DELL XPS 7590

Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHz
32GB SODIMM DDR4 Synchronous 2667 (0.4ns)
PCI bridge: NVIDIA TU117M [GeForce GTX 1650 Mobile / Max-Q]
Hostbridge: Intel UHD Graphics 630 (Mobile)

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-control-center 1:3.36.4-0ubuntu1
ProcVersionSignature: Ubuntu 5.4.0-48.52-generic 5.4.60
Uname: Linux 5.4.0-48-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.9
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Wed Oct 21 17:35:12 2020
InstallationDate: Installed on 2020-04-22 (181 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Beta amd64 (20200402)
SourcePackage: gnome-control-center
UpgradeStatus: No upgrade log present (probably fresh install)

[Daniel van Vugt (vanvugt)]

Please run these commands:

  gsettings get org.gnome.mutter experimental-features > experimental.txt
  lspci -kv > lspci.txt
  journalctl -b0 > journal.txt
  xrandr --verbose > xrandr.txt

and then attach the resulting text files here, along with a copy of your ~/.config/monitors.xml file.

[UV (uvwild)]

here are the requested files.

[Daniel van Vugt (vanvugt)]

Thanks. I think xrandr.txt is the most important file there but it looks like you didn't have any scaling set at the time.

Please enable fractional scaling, even if it is too big, and then run:

  xrandr --verbose > xrandr2.txt
  journalctl -b0 > journal2.txt

and attach the resulting text file here.

[Daniel van Vugt (vanvugt)]

Actually I think bug 1857383 already covers this issue so let's use that.