Public bug reported:
None of the boot parameters worked, but with acpi_backlight=vendor the
backlight was dimmer (systemd-backlight didn't fail). The only way it
starts working is to do "setpci -v -H1 -s 00:01.00 BRIDGE_CONTROL=0"
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: linux-image-5.4.0-45-generic 5.4.0-45.49
ProcVersionSignature: Ubuntu 5.4.0-45.49-generic 5.4.55
Uname: Linux 5.4.0-45-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia wl
ApportVersion: 2.20.11-0ubuntu27.8
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: xma 1345 F.... pulseaudio
/dev/snd/controlC0: xma 1345 F.... pulseaudio
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Tue Sep 1 14:36:14 2020
InstallationDate: Installed on 2020-08-30 (1 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
MachineType: Apple Inc. MacBookPro11,3
ProcFB: 0 EFI VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-45-generic
root=UUID=01482a85-82e8-44ce-a63d-a429cd6d5381 ro acpi_osi=
RelatedPackageVersions:
linux-restricted-modules-5.4.0-45-generic N/A
linux-backports-modules-5.4.0-45-generic N/A
linux-firmware 1.187.3
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/10/2020
dmi.bios.vendor: Apple Inc.
dmi.bios.version: 162.0.0.0.0
dmi.board.asset.tag: Base Board Asset Tag#
dmi.board.name: Mac-2BD1B31983FE1663
dmi.board.vendor: Apple Inc.
dmi.board.version: MacBookPro11,3
dmi.chassis.type: 10
dmi.chassis.vendor: Apple Inc.
dmi.chassis.version: Mac-2BD1B31983FE1663
dmi.modalias:
dmi:bvnAppleInc.:bvr162.0.0.0.0:bd06/10/2020:svnAppleInc.:pnMacBookPro11,3:pvr1.0:rvnAppleInc.:rnMac-2BD1B31983FE1663:rvrMacBookPro11,3:cvnAppleInc.:ct10:cvrMac-2BD1B31983FE1663:
dmi.product.family: Mac
dmi.product.name: MacBookPro11,3
dmi.product.sku: System SKU#
dmi.product.version: 1.0
dmi.sys.vendor: Apple Inc.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug focal
** Attachment added: "backlight.tar"
https://bugs.launchpad.net/bugs/1893795/+attachment/5406558/+files/backlight.tar
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https://bugs.launchpad.net/bugs/1893795
Title:
[Ubuntu 20.04.1 LTS] Backlight brightness can't be changed, even in
/sys/
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