Backlight stays on with black screen when monitor should be sleeping

[Sergey Zolotarev]

My Screen Blank setting is set to 15 minutes. My Lock Screen settings are also set to automatically lock the system after the blank screen timeout is reached.

After 15 minutes Ubuntu does lock me out, but the monitor does not power off as it's supposed to - the screen is simply black. Please see the attached video.

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: xorg 1:7.7+23ubuntu2
ProcVersionSignature: Ubuntu 5.15.0-58.64-generic 5.15.74
Uname: Linux 5.15.0-58-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu82.3
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: unknown
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Wed Jan 18 23:48:13 2023
DistUpgraded: 2022-06-02 20:38:07,324 DEBUG Running PostInstallScript: '/usr/lib/ubuntu-advantage/upgrade_lts_contract.py'
DistroCodename: jammy
DistroVariant: ubuntu
EcryptfsInUse: Yes
ExtraDebuggingInterest: Yes
GraphicsCard:
 Advanced Micro Devices, Inc. [AMD/ATI] Ellesmere [Radeon RX 470/480/570/570X/580/580X/590] [1002:67df] (rev e7) (prog-if 00 [VGA controller])
   Subsystem: Sapphire Technology Limited Radeon RX 570 Pulse 4GB [1da2:e353]
InstallationDate: Installed on 2018-03-17 (1768 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Alpha amd64 (20180316)
MachineType: System manufacturer System Product Name
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.15.0-58-generic root=UUID=19f4e829-52cc-4c6f-8221-24750af577f9 ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to jammy on 2022-06-02 (230 days ago)
dmi.bios.date: 05/29/2019
dmi.bios.release: 5.12
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 4211
dmi.board.asset.tag: Default string
dmi.board.name: H110M-D
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr4211:bd05/29/2019:br5.12:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnH110M-D:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring:skuSKU:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: SKU
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.110-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 22.0.5-0ubuntu0.3
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core 2:21.1.3-2ubuntu2.5
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.1.0-2ubuntu1
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)]

See also https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/6326

[Launchpad Janitor (janitor)]

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

[Daniel van Vugt (vanvugt)]

When the lock screen appears after the black screen, is that because you pressed a key or does the lock screen appear all by itself? If the latter then the problem with monitors cycling inputs and then waking the machine up is also reported in https://gitlab.gnome.org/GNOME/mutter/-/issues/1021

[Sergey Zolotarev (szx)]

That was me pressing a button, correct. The lock screen does not appear by itself for me.

[Launchpad Janitor (janitor)]

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

[Daniel van Vugt (vanvugt)]

Try adding this to /etc/environment:

  MUTTER_DEBUG_ENABLE_ATOMIC_KMS=0

and then reboot.

[Daniel van Vugt (vanvugt)]

Please also try to capture the part of the system log (using journalctl) showing when the problem occured.

[Sergey Zolotarev (szx)]

Adding MUTTER_DEBUG_ENABLE_ATOMIC_KMS=0 did not have any visible effect

[Michał Fita (michal.fita)]

I've dumped my log in #2007268. Setting the variable didn't change anything in terms of backlight as in @szx case.

[Michał Fita (michal.fita)]

Worth adding, my screen doesn't show "No signal".

[Daniel van Vugt (vanvugt)]

Now tracking in bug 1971434.