[Star LabTop (Mk III)] Screen backlight pulses rapidly when cursor is still, but i915.enable_psr=0 fixes it

[Fiona Hinman]

The backlight for my display appears to brighten and dim rapidly whenever the mouse cursor is still, but stops when the cursor is being moved. The pulsing backlight is distracting and causes eye strain. Same issue experienced on Ubuntu 19.04 before upgrading.

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: xorg 1:7.7+19ubuntu12
ProcVersionSignature: Ubuntu 5.3.0-19.20-generic 5.3.1
Uname: Linux 5.3.0-19-generic x86_64
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Sun Oct 27 13:08:24 2019
DistUpgraded: 2019-10-22 00:34:33,817 ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: Failed to execute child process “./xorg_fix_proprietary.py” (No such file or directory) (8))
DistroCodename: eoan
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation UHD Graphics 620 [8086:5917] (rev 07) (prog-if 00 [VGA controller])
   Subsystem: Intel Corporation UHD Graphics 620 [8086:5917]
InstallationDate: Installed on 2019-10-08 (19 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
Lsusb:
 Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
 Bus 001 Device 005: ID 0bda:0129 Realtek Semiconductor Corp. RTS5129 Card Reader Controller
 Bus 001 Device 004: ID 8087:0a2b Intel Corp.
 Bus 001 Device 003: ID 1bcf:2085 Sunplus Innovation Technology Inc. HP HD Camera
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Star Labs LabTop
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-19-generic root=UUID=f6561506-cd05-4022-b582-c38a0a405d1b ro quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to eoan on 2019-10-22 (5 days ago)
dmi.bios.date: 07/05/2019
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V1.0.09
dmi.board.asset.tag: Default string
dmi.board.name: Star LabTop (Mk III)
dmi.board.vendor: Star Labs Online Limited
dmi.board.version: Default string
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 10
dmi.chassis.vendor: Star Labs
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV1.0.09:bd07/05/2019:svnStarLabs:pnLabTop:pvrDefaultstring:rvnStarLabsOnlineLimited:rnStarLabTop(MkIII):rvrDefaultstring:cvnStarLabs:ct10:cvrDefaultstring:
dmi.product.family: KBLR_NB_133
dmi.product.name: LabTop
dmi.product.sku: L3-U
dmi.product.version: Default string
dmi.sys.vendor: Star Labs
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.99-1ubuntu1
version.libgl1-mesa-dri: libgl1-mesa-dri 19.2.1-1ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx N/A
version.xserver-xorg-core: xserver-xorg-core 2:1.20.5+git20191008-0ubuntu1
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:19.0.1-1ubuntu1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20190815-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.16-1
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu8
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: fiona 1724 F.... pulseaudio
CurrentDesktop: ubuntu:GNOME
DistroRelease: Ubuntu 19.10
InstallationDate: Installed on 2019-10-08 (19 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Release amd64 (20190416)
MachineType: Star Labs LabTop
Package: mutter 3.34.1-1ubuntu1
PackageArchitecture: amd64
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.3.0-19-generic root=UUID=f6561506-cd05-4022-b582-c38a0a405d1b ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 5.3.0-19.20-generic 5.3.1
RelatedPackageVersions:
 linux-restricted-modules-5.3.0-19-generic N/A
 linux-backports-modules-5.3.0-19-generic N/A
 linux-firmware 1.183.1
Tags: eoan
Uname: Linux 5.3.0-19-generic x86_64
UpgradeStatus: Upgraded to eoan on 2019-10-22 (5 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo
_MarkForUpload: True
dmi.bios.date: 07/05/2019
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: V1.0.09
dmi.board.asset.tag: Default string
dmi.board.name: Star LabTop (Mk III)
dmi.board.vendor: Star Labs Online Limited
dmi.board.version: Default string
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 10
dmi.chassis.vendor: Star Labs
dmi.chassis.version: Default string
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrV1.0.09:bd07/05/2019:svnStarLabs:pnLabTop:pvrDefaultstring:rvnStarLabsOnlineLimited:rnStarLabTop(MkIII):rvrDefaultstring:cvnStarLabs:ct10:cvrDefaultstring:
dmi.product.family: KBLR_NB_133
dmi.product.name: LabTop
dmi.product.sku: L3-U
dmi.product.version: Default string
dmi.sys.vendor: Star Labs

[Daniel van Vugt (vanvugt)]

Please check to see if your laptop has this option, and if so then turn it off:

Settings > Power > Automatic Brightness

[Fiona Hinman (greedylizard)]

There is not an automatic brightness setting on my laptop.

[Ubuntu Kernel Bot (ubuntu-kernel-bot)]

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1850066

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

[Fiona Hinman (greedylizard)]

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[Kai-Heng Feng (kaihengfeng)]

Does '/sys/class/backlight/intel_backlight/brightness' rapidly change when this issue happens?

[Fiona Hinman (greedylizard)]

The brightness number does not seem to fluctuate, so it might be a different issue than the backlight that creates the pulsing effect.

[Daniel van Vugt (vanvugt)]

I wonder if the problem is related to panel self refresh, since it is affected by hardware cursor movement.

Please try adding kernel parameter:

  i915.enable_psr=0

to GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub and then run:

  sudo update-grub

and reboot.

If that's the problem then it would make sense this bug is specific to the model of LCD in this laptop.

https://www.kernel.org/doc/html/v5.3/gpu/i915.html#panel-self-refresh-psr-psr-srd
https://wiki.archlinux.org/index.php/intel_graphics#Screen_flickering

[Fiona Hinman (greedylizard)]

After adding the kernel parameter specified, the problem has been resolved. Thank you so much for the help!

[Kai-Heng Feng (kaihengfeng)]

Please test latest drm-tip kernel without the PSR parameter:
https://kernel.ubuntu.com/~kernel-ppa/mainline/drm-tip/current/

If it doesn't solve the issue, please file an upstream bug at https://bugs.freedesktop.org/
Product: DRI
Component: DRM/i915