99.98Hz display mode is sometimes missing on USB-C (DisplayPort) external monitor, which resets the display layout

[Freeman]

When rebooting with USB-C external monitor (3440x1440) attached, display orientation in "gnome-control-center display" resets requiring one to reposition the windows on boot. Very annoying.

In addition, refresh rate drop down for external display sometimes goes missing when setting refresh rate to 100hz instead of default 60?Hz. Refresh rate listing and dropdown box disappears until setting monitor resolution to different resolution and back or reboot.

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: gnome-control-center 1:3.38.5-1ubuntu1
ProcVersionSignature: Ubuntu 5.11.0-13.14-generic 5.11.7
Uname: Linux 5.11.0-13-generic x86_64
ApportVersion: 2.20.11-0ubuntu61
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 5 01:09:38 2021
InstallationDate: Installed on 2021-04-05 (0 days ago)
InstallationMedia: Ubuntu 21.04 "Hirsute Hippo" - Beta amd64 (20210331.1)
ProcEnviron:
 LANGUAGE=en_CA:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-control-center
UpgradeStatus: No upgrade log present (probably fresh install)

[Sebastien Bacher (seb128)]

Thank you for your bug report, gnome-control-center isn't in charge of loading configurations on login though, reassigning

[Daniel van Vugt (vanvugt)]

Thanks for the bug report.

Please reproduce the problem and then run:

  journalctl -b0 > journal.txt
  lspci -kv > lspci.txt
  xrandr --verbose > xrandr.txt

and attach the resulting text files here.

[Freeman (gordon.freeman)]

https://paste.ubuntu.com/p/xKKDBJgPDB/ <- Journal.txt
https://paste.ubuntu.com/p/65Zr3dVCk3/ <- lspci.txt
https://paste.ubuntu.com/p/4P27dDrvvV/ <- xrandr.txt

[Freeman (gordon.freeman)]

The above was after booting, and the orientations were reset.

The below is after booting, and then trying to change the refresh rate and having it bug out and the refresh rate dropdown selection disappear. The 100Hz @ 3440x1440 works fine in Windows but its extremely buggy in Ubuntu hirsute hippo.

https://paste.ubuntu.com/p/yKGfCCPGW3/ <- Journal.txt
https://paste.ubuntu.com/p/XPgN6x656s/ <- lspci.txt
https://paste.ubuntu.com/p/8PJKHBymn5/ <- xrandr.txt

[Daniel van Vugt (vanvugt)]

Please try selecting 'Ubuntu on Xorg' from the login screen (button in the bottom right corner of the screen) and then run this command again:

  xrandr --verbose > xorgxrandr.txt

and attach the resulting text file here. Does the same bug occur in Xorg?

[Freeman (gordon.freeman)]

This is the xrandr after just switching to gnome of xorg

[Freeman (gordon.freeman)]

Then this is the xrandr after switching refresh rate to 100hz (successful) in Ubuntu on Xorg.

[Freeman (gordon.freeman)]

And then this is the xrandr after rebooting and losing my screen orientation under Ubuntu on Xorg and having the refresh rate reset to 60hz on the external monitor.

[Daniel van Vugt (vanvugt)]

Thanks. That indeed confirms the 99.98Hz mode has suddenly gone missing in the last attachment. The system seems to be treating that as a different monitor configuration and will revert to defaults (which is landscape and 59.97Hz).

When this happens though, the monitor's EDID does not change. It still reports the 99.98Hz mode exists:

Detailed mode: Clock 543.500 MHz, 797 mm x 333 mm
               3440 3488 3520 3600 ( 48 32 80)
               1440 1443 1453 1510 ( 3 10 57)
               +hsync -vsync
               VertFreq: 99.982 Hz, HorFreq: 150.972 kHz

So if the mode exists but is not offered as an option then that suggests the kernel or driver thinks there's not enough bandwidth or a good enough connection to support that particular mode. Therefore, please try a different monitor cable.

[Freeman (gordon.freeman)]

If I bring up the display switching menu and select external display only it lets me switch the refresh rate after it bugging out and not showing the refresh rate selector in gnome-settings.

[Kai-Heng Feng (kaihengfeng)]

First, please test latest drm-tip kernel:
https://kernel.ubuntu.com/~kernel-ppa/mainline/drm-tip/current/

[Launchpad Janitor (janitor)]

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]