Public bug reported:
Ubuntu 26.04 LTS, kernel 7.0.0-29-generic, GNOME/Wayland
Hardware: Dell Alienware m16 R2
iGPU: Intel Meteor Lake-P [Arc Graphics] (i915) -> eDP-1, 1920x1200 240Hz BOE
panel
dGPU: NVIDIA RTX 4070 Max-Q (nvidia-open 595.84) -> HDMI-A-1
PRIME: on-demand
Summary
-------
With an external monitor connected via HDMI (on the NVIDIA GPU), mutter
selects the internal panel's maximum mode, 1920x1200 @ 239.944Hz. This
mode cannot be committed. The internal panel then goes permanently dark
and mutter never falls back to a lower mode.
The panel is NOT lost at the hardware level throughout:
- /sys/class/drm/card1-eDP-1/status reports "connected"
- backlight (nvidia_wmi_ec_backlight) accepts writes; actual_brightness
confirmed at 220/255 while the screen was dark
- switching to a text VT (chvt 3) lights the panel correctly
- the Plymouth shutdown animation displays correctly on the panel
Only mutter fails to drive it.
Errors
------
gnome-shell: Cursor update failed: drmModeAtomicCommit: Invalid argument
gnome-shell: meta_monitor_manager_get_logical_monitor_from_number:
assertion '(unsigned int) number < g_list_length (manager->logical_monitors)'
failed
gnome-shell: meta_workspace_get_work_area_for_monitor:
assertion 'logical_monitor != NULL' failed
The assertions indicate eDP-1 has been dropped from mutter's logical
monitor list while the rest of the shell still references it.
Persistence
-----------
Restarting gdm does NOT recover the panel - the GDM greeter itself does
not appear on it (password must be typed blind). Removing
~/.config/monitors.xml does not help either: mutter regenerates a
configuration and again selects the panel's EDID-preferred maximum rate.
Workaround
----------
Settings > Displays > set eDP-1 refresh rate to 60Hz. The panel returns
immediately and stays working.
Expected behaviour
------------------
When an atomic commit for a selected mode fails, mutter should fall back
to a lower mode rather than dropping the output entirely, and should not
leave the connector dark with no in-session recovery path.
Attaching: full journal for the affected boot, and the monitors.xml
containing the 239.944Hz entry.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: libmutter-18-0 50.1-0ubuntu2.2
ProcVersionSignature: Ubuntu 7.0.0-29.29-generic 7.0.12
Uname: Linux 7.0.0-29-generic x86_64
ApportVersion: 2.34.1-0ubuntu0.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Aug 11 11:47:58 2026
InstallationDate: Installed on 2025-12-17 (237 days ago)
InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
SourcePackage: mutter
UpgradeStatus: Upgraded to resolute on 2026-07-05 (37 days ago)
** Affects: mutter (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2163251
Title:
mutter applies uncommittable 239.944Hz mode to eDP-1 on hybrid
Intel+NVIDIA, internal panel goes permanently dark with no fallback
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/mutter/+bug/2163251/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
