[i915] TILEd monitor not getting full res

[Jerker Nordh]

I have an LG 34WK95U monitor which appears to be tiled using two diplay port interfaces connect over thunderbolt. I'm unable to get ubuntu to drive the monitor at it's full 5120x2160@60 resolution.

Manually I can force it to 5120x2160@30, but by default Ubuntu gives me 3440x1440@60.

I've been researching what the problem might be, my findings so far are collected in these two questions on askubuntu
https://askubuntu.com/questions/1233284/tiled-monitor-support-lg-34wk95u
https://askubuntu.com/questions/1230124/high-res-monitor-support-5120x2160-lg-34wk95

I've tried switching my laptop gpu from NVidia to the built-in Intel, but the problem persists. The monitor worked in Windows before I wiped the laptop to install Ubuntu.

So I'm stuck with the conclusion that there is a bug somewhere at a lower layer preventing this from working since none of the things I've tested have worked. Ideally this should of course have worked out of the box as on Windows.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xorg 1:7.7+19ubuntu14
ProcVersionSignature: Ubuntu 5.4.0-28.32-generic 5.4.30
Uname: Linux 5.4.0-28-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
.proc.driver.nvidia.gpus.0000.01.00.0: Error: [Errno 21] Is a directory: '/proc/driver/nvidia/gpus/0000:01:00.0'
.proc.driver.nvidia.registry: Binary: ""
.proc.driver.nvidia.suspend: suspend hibernate resume
.proc.driver.nvidia.suspend_depth: default modeset uvm
.proc.driver.nvidia.version:
 NVRM version: NVIDIA UNIX x86_64 Kernel Module 440.64 Fri Feb 21 01:17:26 UTC 2020
 GCC version: gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu2)
ApportVersion: 2.20.11-0ubuntu27
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: skip
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Mon May 4 12:33:55 2020
DistUpgraded: Fresh install
DistroCodename: focal
DistroVariant: ubuntu
DkmsStatus: nvidia, 440.64, 5.4.0-28-generic, x86_64: installed
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
 Intel Corporation UHD Graphics 630 (Mobile) [8086:3e9b] (rev 02) (prog-if 00 [VGA controller])
   Subsystem: Dell UHD Graphics 630 (Mobile) [1028:0906]
   Subsystem: Dell TU117GLM [Quadro T2000 Mobile / Max-Q] [1028:0906]
InstallationDate: Installed on 2020-04-24 (10 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
MachineType: Dell Inc. Precision 5540
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.4.0-28-generic root=/dev/mapper/vgubuntu-root ro quiet splash
SourcePackage: xorg
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/25/2019
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.5.0
dmi.board.name: 0FMYX6
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.5.0:bd12/25/2019:svnDellInc.:pnPrecision5540:pvr:rvnDellInc.:rn0FMYX6:rvrA00:cvnDellInc.:ct10:cvr:
dmi.product.family: Precision
dmi.product.name: Precision 5540
dmi.product.sku: 0906
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.101-2
version.libgl1-mesa-dri: libgl1-mesa-dri 20.0.4-2ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.nvidia-graphics-drivers: nvidia-graphics-drivers-* N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.8-2ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20200226-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1

[Jerker Nordh (ajn)]

The 2560x2160R module visible in the xrandr output was me manually trying to force it, it's not there by default. The regular 250xs2160 mode is available on DP-1-2 output ony by default.

[Daniel van Vugt (vanvugt)]

mutter 3.36.2 fixes tiled monitor support for Wayland, but looking at that fix it also seems to share code with X11. So maybe that will help here too.

Please wait till 3.36.2 is released as an update and then if the problem is still not fixed please open a new bug at:

  https://gitlab.gnome.org/GNOME/mutter/issues

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Jerker Nordh (ajn)]

This seems to have been a kernel issue, it's fixed with Linux 5.9rc1.
For more details see here
https://gitlab.freedesktop.org/drm/intel/-/issues/27

[Daniel van Vugt (vanvugt)]

It appears that fix (dc5b8ed56bb) is in groovy, but not focal.

[Ingo Reimann (ubuntu-i-reimann)]

Hi,
I`m with focal on an Dell XPS15-9560 (i7-7700HQ/i915/Intel HD630, nVidia GTX 1050 Mobile) with kernel 5.11, mutter 3.36.9 For me everything works!