** Changed in: mutter (Ubuntu Noble)
Assignee: (unassigned) => Alessandro Astone (aleasto)
** Changed in: mutter (Ubuntu Noble)
Status: Triaged => Fix Committed
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https://bugs.launchpad.net/bugs/1971434
Title:
Display powersave only blanks, but does not turn off
Status in GNOME Settings Daemon:
New
Status in Mutter:
New
Status in mutter package in Ubuntu:
Fix Released
Status in mutter source package in Jammy:
Triaged
Status in mutter source package in Noble:
Fix Committed
Status in mutter source package in Oracular:
Won't Fix
Status in mutter source package in Plucky:
Fix Released
Status in mutter source package in Questing:
Fix Released
Bug description:
[ Impact ]
On some machines when the screen blanks, the LCD backlight stays on.
This was traced to two issues in mutter:
https://gitlab.freedesktop.org/drm/amd/-/issues/662#note_2731990
> I recently discovered that mutter was disabling DPMS off again on receiving
a hotplug event from udev. I don't know any reason for that, removing it allows
my monitor to go to sleep eventually. Note that when mutter runs on Xorg, it
doesn't explicitly disable DPMS off but just queries the current DPMS state
from Xorg. Since the issues are reproducible with Xorg and other Wayland DEs,
maybe Xorg drivers and other Wayland compositors do something like what mutter
did as well.
> On receiving a hotplug event from udev, mutter now waits until no further
hotplug events have arrived for at least one second, only then does it query
the current KMS state. This avoids issues due to monitors generating hotplug
events and temporarily appearing disconnected. It might be nice if something
like this was done in the kernel if possible, not sending any hotplug event to
user space if EDID hasn't changed, or something along those lines.
[ Workarounds (reported to work by some people) ]
* Configure the monitor (in its own menus) to not auto-switch inputs.
* Change from HDMI to DisplayPort cables.
* Disable HDMI audio output.
[ Test Plan ]
0. Make sure you're using an LCD (not OLED) so you can see if the backlight
is on.
1. Log-in to an Ubuntu Wayland desktop session
2. In Settings -> Power -> Screen Blank, set the inactivity period to 1
minute.
3. Verify after 1 minute that the screen is blank and the backlight is also
visibly off.
4. Verify that the screen is turned back on after interacting with the system.
[ Regression Test Plan ]
1. Plug in a monitor:
-> Verify that the desktop extends to the new monitor
2. Unplug a monitor:
-> Verify that mutter does not crash and log you out
[ Where problems could occur ]
Mutter is the GNOME component driving the display.
The patches modify how mutter reacts to monitor hotplug events and when it
should turn the monitor back ON.
Problems would manifest when plugging in/out monitors.
The "Regression Test Plan" tries to verify that no regressions are introduced.
To manage notifications about this bug go to:
https://bugs.launchpad.net/gnome-settings-daemon/+bug/1971434/+subscriptions
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