Comment 0 for bug 1860303

I cannot adjust the screen brightness using the keyboard keys or changing /sys/call/backlight/intel_backlight/brightness values. I've only been able to adjust the backlight using xrandr.

Followed bug report on https://wiki.ubuntu.com/Kernel/Debugging/Backlight#Diagnostic_Techniques and attached files. Additional information:
1. echo 8 > /sys/class/backlight/intel_backlight/brightness does not change the screen brightness
2. video.use_bios_initial_backlight=0 does not enable brightness to be changed
3. Cannot login to when using kernel paramater acpi_osi=. Login does not work and on one boot "y"s were being continuously typed without any keys being depressed. It was odd.
4. video.use_native_backlight=1 does not enabel brightness to be changed
5. Created file /usr/share/X11/xorg.conf.d/80-backlight.conf and it had no impact

ProblemType: Bug
DistroRelease: Ubuntu 19.10
Package: linux-image-5.3.0-26-generic 5.3.0-26.28
ProcVersionSignature: Ubuntu 5.3.0-26.28-generic 5.3.13
Uname: Linux 5.3.0-26-generic x86_64
ApportVersion: 2.20.11-0ubuntu8.2
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC0: jaredy 1649 F.... pulseaudio
 /dev/snd/pcmC0D0p: jaredy 1649 F...m pulseaudio
CurrentDesktop: ubuntu:GNOME
Date: Sun Jan 19 19:51:45 2020
InstallationDate: Installed on 2020-01-03 (16 days ago)
InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017)
MachineType: HP HP Spectre x360 Convertible 13t-aw100
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-5.3.0-26-generic root=UUID=5f505587-b59b-4abd-b8f2-28c04ab84c64 ro quiet splash acpi_backlight=vendor vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-5.3.0-26-generic N/A
 linux-backports-modules-5.3.0-26-generic N/A
 linux-firmware 1.183.3
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/15/2019
dmi.bios.vendor: AMI
dmi.bios.version: F.10
dmi.board.asset.tag: Base Board Asset Tag
dmi.board.name: 86FA
dmi.board.vendor: HP
dmi.board.version: 87.43
dmi.chassis.type: 31
dmi.chassis.vendor: HP
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAMI:bvrF.10:bd11/15/2019:svnHP:pnHPSpectrex360Convertible13t-aw100:pvr:rvnHP:rn86FA:rvr87.43:cvnHP:ct31:cvrChassisVersion:
dmi.product.family: 103C_5335KV HP Spectre
dmi.product.name: HP Spectre x360 Convertible 13t-aw100
dmi.product.sku: 6YG70AV
dmi.sys.vendor: HP