display backlight turns full on every minute

[Alexander Gordeev]

Today I started working at about 6 am with lights off before the sunrise. So I set the display backlight on my notebook at the minimum. I used notebook keyboard buttons for this. Then I realised that night light (which makes display colors warm) is already off. I opened Settings window, navigated to Devices -> Monitors screen and set the night light to the manual mode. I changed the upper limit to 8 am. The night light turned on immediately. Then I closed the Settings window. I worked for about an hour till 7 am. Then suddenly the backlight of the display started to turn full on about every minute. I changed it to the previous low level with the buttons but it kept turning full on in after about a minute. Changing any settings in the Power tab didn't help. The only thing that helped was:
chmod -w /sys/class/backlight/*/brightness
After I ran the command the problem is gone. The only effect I still see is: the slider in the Power tab of the settings window is switching to the full on position about every minute. Without any input from me of course.

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: xorg 1:7.7+19ubuntu3
ProcVersionSignature: Ubuntu 4.13.0-17.20-generic 4.13.8
Uname: Linux 4.13.0-17-generic x86_64
ApportVersion: 2.20.7-0ubuntu3.6
Architecture: amd64
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Sun Dec 10 07:35:33 2017
DistUpgraded: Fresh install
DistroCodename: artful
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
 Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller [8086:2a42] (rev 07) (prog-if 00 [VGA controller])
   Subsystem: Acer Incorporated [ALI] Mobile 4 Series Chipset Integrated Graphics Controller [1025:0283]
   Subsystem: Acer Incorporated [ALI] Mobile 4 Series Chipset Integrated Graphics Controller [1025:0283]
InstallationDate: Installed on 2017-11-08 (31 days ago)
InstallationMedia: Ubuntu 17.10 "Artful Aardvark" - Release amd64 (20171018)
MachineType: Acer TravelMate 8371
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=ru_RU.UTF-8
 SHELL=/bin/bash
ProcKernelCmdLine: BOOT_IMAGE=/root_17_10/boot/vmlinuz-4.13.0-17-generic root=UUID=11364c2e-2856-412a-86ed-f2a02c62fbce ro rootflags=subvol=root_17_10 quiet splash vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/26/2010
dmi.bios.vendor: Acer
dmi.bios.version: V1.27
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: TravelMate 8371
dmi.board.vendor: Acer
dmi.board.version: PSMBOU-1234567
dmi.chassis.asset.tag: None
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: None
dmi.modalias: dmi:bvnAcer:bvrV1.27:bd03/26/2010:svnAcer:pnTravelMate8371:pvrV1.27:rvnAcer:rnTravelMate8371:rvrPSMBOU-1234567:cvnAcer:ct10:cvrNone:
dmi.product.family: Intel_Mobile
dmi.product.name: TravelMate 8371
dmi.product.version: V1.27
dmi.sys.vendor: Acer
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.83-1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.2.2-0ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 17.2.2-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.5-0ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.10.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20170309-0ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2