[Wayland] Backlight stays on with black screen when monitor should be sleeping

[Zingam]

In Power -> Power Saving Options -> Screen Blank - the option states that the screen will be turned off after some period, which is what I'd expect from a sleep mode.

I have a hybrid system. I have disabled the internal display and I use the external connected via HDMI (and I believe it is connected to the NVIDIA GPU). When the screen goes blank the external monitor is not turned off really. It goes blank but it is still turned on and glows, so no power is saved.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: xorg 1:7.7+23ubuntu2
ProcVersionSignature: Ubuntu 5.15.0-27.28-generic 5.15.30
Uname: Linux 5.15.0-27-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
.proc.driver.nvidia.capabilities.gpu0: Error: path was not a regular file.
.proc.driver.nvidia.capabilities.mig: Error: path was not a regular file.
.proc.driver.nvidia.gpus.0000.01.00.0: Error: path was not a regular file.
.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 510.60.02 Wed Mar 16 11:24:05 UTC 2022
 GCC version:
ApportVersion: 2.20.11-0ubuntu82
Architecture: amd64
CasperMD5CheckResult: pass
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Sun May 15 19:16:56 2022
DistUpgraded: Fresh install
DistroCodename: jammy
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
 Intel Corporation HD Graphics 630 [8086:591b] (rev 04) (prog-if 00 [VGA controller])
   Subsystem: Dell HD Graphics 630 [1028:0798]
 NVIDIA Corporation GP107M [GeForce GTX 1050 Ti Mobile] [10de:1c8c] (rev a1) (prog-if 00 [VGA controller])
   Subsystem: Dell GP107M [GeForce GTX 1050 Ti Mobile] [1028:0798]
InstallationDate: Installed on 2022-05-01 (14 days ago)
InstallationMedia: Ubuntu 22.04 LTS "Jammy Jellyfish" - Release amd64 (20220419)
MachineType: Dell Inc. Inspiron 15 7000 Gaming
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.15.0-27-generic root=UUID=19e3ad11-d1ce-49ce-8809-80fc68612eb3 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/30/2021
dmi.bios.release: 1.15
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.15.0
dmi.board.name: 065C71
dmi.board.vendor: Dell Inc.
dmi.board.version: X02
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.15.0:bd08/30/2021:br1.15:svnDellInc.:pnInspiron157000Gaming:pvr:rvnDellInc.:rn065C71:rvrX02:cvnDellInc.:ct10:cvr:sku0798:
dmi.product.family: Inspiron
dmi.product.name: Inspiron 15 7000 Gaming
dmi.product.sku: 0798
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.110-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 22.0.1-1ubuntu2
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 2:21.1.3-2ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-2build3
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20210115-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.17-2build1

[Daniel van Vugt (vanvugt)]

Does the same bug occur if you choose a Xorg session (or just non-Wayland) on the login screen?

[Zingam (registrirayme)]

I tried this just once in Xorg session.

These two issues didn't occur:

1. External monitor was turned off during sleep
2. Internal display did turn on after waking from sleep

In a Wayland session

1. On sleep: The External monitor glows but is blank. The internal display doesn't glow.
2. On wake: The External display wakes up. The internal display doesn't wake up.

(2.) was reported separately but I can't find it any longer. I think you said that the something crashed in the attached log report.

[Zingam (registrirayme)]

I tried a few more times and none of the issues I have with Wayland are present with Xorg:

1. External monitor doesn't turn off during sleep
2. Internal display doesn't wake up from sleep
3. Crashes while resizing snapped/joined windows fast continously
4. No nightlight
5. Mozilla (XWayland) leaves artifacts (part of the image) on the desktop when restoring window from full-screen when playing YouTube videos.
6. Inconsistent desktop GNOME performance, mouse doesn't feel smooth

I reported or voted for all of the above.

[Zingam (registrirayme)]

I don't know if the following is related but I made settings according to: https://bugs.launchpad.net/gnome-shell/+bug/1968040

I added this option:

MUTTER_DEBUG_ENABLE_ATOMIC_KMS=0

to

/etc/environment

Now both screens don't turn off - the internal screen and the external screen. The screens just get blank.

[Launchpad Janitor (janitor)]

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

[Richard Wissbaum (rjwissbaum)]

I just upgraded from 20.4 LTS today and have the exact same problem.I have an HP Pavilion desktop and an external monitor (unknown video card).

My screen goes blank after the specific interval of no activity, but the monitor does not enter standby mode, so the "blank" screen glows through the night...

[Daniel van Vugt (vanvugt)]

I wonder if this is caused by uncoordinated KMS updates not relating to displaying the primary plane. I imagine some of those will wake the monitor up even though there's no image to display. And even worse; some of them will come from gnome-settings-daemon beyond the control of gnome-shell/mutter (which is fixed in GNOME 43). To mitigate this, please try disabling features that might cause such updates:

 * Settings > Colour > turn OFF for all screens
 * Settings > Screen Display > Night Light = OFF
 * Software-controlled privacy screens on some models of laptop

[Michał Fita (michal.fita)]

Interesting thing is that I've reinstalled Kubuntu recently, then added Wayland. Plasma on Wayland seem to disable screens correctly.

I've installed `ubuntu-desktop` and switch again to Gnome... and screens remain backlighted. This time I haven't added any extensions.

Maybe some studies how Plasma deals with that would help solve this annoying issue?

[Robin Sheat (eythian)]

This also affects me, with a dual-monitor - laptop screen + one external monitor - setup (it's harder to tell if it also happens without the second monitor but I can check that if useful.) The second monitor is connected by either HDMI direct or HDMI via a thunderbolt dongle, and it happens in both cases. The only GPU in this laptop is i915, and it's running Ubuntu 22.04.

It's maybe notable that in some but not all cases, I'll return and the mouse pointer is visible on the otherwise black screen.

Also, it's not smooth. If I lock with super-L:
* I get the lock screen
* after a second, the lock screen fades to black, the laptop screen goes blank (maybe DPMS-off, it's hard to tell) and the external monitor reports "no signal" and turns itself off after a short moment
* they remains off for a few seconds
* they then wake up again and show the lock screen
* after some time (20 seconds maybe) the external says "no signal" again and then powers off, laptop screen goes blank
* it wakes up again, back at the lock screen
* it settles on on with the lock screen showing, no change for a few minutes

That's where I stopped, but I suspect that after some time the screen blanker turns the display blank but doesn't power things off. I can get a more precise sequence if it'd be useful. I ran these with both colour profiles and nightlight disabled, though they were previously enabled.

My hypothesis is that the monitor turning off causes some event that causes Gnome to wake it up (in the past I've noticed windows moving from one screen to another, as if it were unplugged, but I haven't seen that recently), and then some other "let's not repeatedly power cycle things" check stops it happening too much. But that's 100% speculation.

[Daniel van Vugt (vanvugt)]

Removing the nvidia-wayland tag because the bug clearly isn't specific to Wayland on Nvidia. Also the duplicate bugs don't have Nvidia at all.

[Michał Fita (michal.fita)]

The problem persists with 23.04 and now with 23.10 as well from what I see. The only difference is that if I turn off the HDMI screen, the notebook screen can disable backlight over time.