After upgrading from Ubuntu 17.10 to 18.04 the screen backlight is unstable (oscillating), when not set to the minimum or maximum values.
ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: xorg 1:7.7+19ubuntu7
ProcVersionSignature: Ubuntu 4.15.0-24.26-generic 4.15.18
Uname: Linux 4.15.0-24-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
BootLog:
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Thu Jul 12 21:46:46 2018
DistUpgraded: 2018-07-04 10:15:00,611 ERROR got error from PostInstallScript ./xorg_fix_proprietary.py (g-exec-error-quark: L’exécution du processus fils « ./xorg_fix_proprietary.py » a échoué (Aucun fichier ou dossier de ce type) (8))
DistroCodename: bionic
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, if not too technical
GraphicsCard:
Intel Corporation HD Graphics 620 [8086:5916] (rev 02) (prog-if 00 [VGA controller])
Subsystem: Dell HD Graphics 620 [1028:07a4]
InstallationDate: Installed on 2017-10-16 (269 days ago)
InstallationMedia: Ubuntu-GNOME 17.04 "Zesty Zapus" - Release amd64 (20170412)
Lsusb:
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 8087:0a2b Intel Corp.
Bus 001 Device 002: ID 044e:1218 Alps Electric Co., Ltd
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
MachineType: Dell Inc. Latitude 5285
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-4.15.0-24-generic root=/dev/mapper/ubuntu--gnome--vg-root ro no_console_suspend initcall_debug acpi_osi=Linux acpi_backlight=vendor
SourcePackage: xorg
Symptom: display
UpgradeStatus: Upgraded to bionic on 2018-07-04 (8 days ago)
dmi.bios.date: 12/10/2017
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.3.1
dmi.board.name: 0T9FCR
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 32
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvr1.3.1:bd12/10/2017:svnDellInc.:pnLatitude5285:pvr:rvnDellInc.:rn0T9FCR:rvrA00:cvnDellInc.:ct32:cvr:
dmi.product.family: Latitude
dmi.product.name: Latitude 5285
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.91-2
version.libgl1-mesa-dri: libgl1-mesa-dri 18.0.5-0ubuntu0~18.04.1
version.libgl1-mesa-glx: libgl1-mesa-glx 18.0.5-0ubuntu0~18.04.1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.6-1ubuntu4
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:18.0.1-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20171229-1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2
I know it's annoying. Not all laptops support auto-brightness but if yours does then you will find it's an option in Settings > Power (?) you can just turn off. Try that.