Public bug reported:
The screen brightness controls don't work on the Legion Slim 7 (AMD)
laptop running in hybrid/dynamic mode.
The backlight control files appear in /sys/class/backlight/amdgpu_bl0,
and writing to /sys/class/backlight/amdgpu_bl0/brightness changes the
value in /sys/class/backlight/amdgpu_bl0/actual_brightness, but the
screen brightness always remains at 100%.
I have tried kernel boot parameters:
acpi_backlight=vendor
amdgpu.backlight=0
but neither makes any difference.
I have read that users with the Legion 7 AMD and Legion 5 Pro AMD can
get the backlight working with the amdgpu.backlight=0 kernel boot
parameter. One difference between them and this laptop is that it has
advanced optimus, meaning that it can switch the laptop display between
the amdgpu and nvidia card without rebooting, if that is at all
relevant.
ProblemType: Bug
DistroRelease: Ubuntu 21.10
Package: linux-image-5.13.0-16-generic 5.13.0-16.16
ProcVersionSignature: Ubuntu 5.13.0-16.16-generic 5.13.13
Uname: Linux 5.13.0-16-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu69
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: rocko 1978 F.... pulseaudio
/dev/snd/controlC1: rocko 1978 F.... pulseaudio
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Mon Sep 20 09:20:33 2021
InstallationDate: Installed on 2021-09-15 (5 days ago)
InstallationMedia: Ubuntu 21.10 "Impish Indri" - Alpha amd64 (20210910)
MachineType: LENOVO 82K8
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-5.13.0-16-generic
root=UUID=99f436de-d37c-4b3e-adb2-612443efc197 ro rootflags=subvol=@ quiet
splash amdgpu.backlight=0 vt.handoff=7
PulseList:
Error: command ['pacmd', 'list'] failed with exit code 1: XDG_RUNTIME_DIR
(/run/user/1001) is not owned by us (uid 0), but by uid 1001! (This could e.g.
happen if you try to connect to a non-root PulseAudio as a root user, over the
native protocol. Don't do that.)
No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-5.13.0-16-generic N/A
linux-backports-modules-5.13.0-16-generic N/A
linux-firmware 1.200
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 08/02/2021
dmi.bios.release: 1.27
dmi.bios.vendor: LENOVO
dmi.bios.version: HACN27WW
dmi.board.asset.tag: No Asset Tag
dmi.board.name: LNVNB161216
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40697WIN
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: Legion S7 15ACH6
dmi.ec.firmware.release: 1.27
dmi.modalias:
dmi:bvnLENOVO:bvrHACN27WW:bd08/02/2021:br1.27:efr1.27:svnLENOVO:pn82K8:pvrLegionS715ACH6:skuLENOVO_MT_82K8_BU_idea_FM_LegionS715ACH6:rvnLENOVO:rnLNVNB161216:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrLegionS715ACH6:
dmi.product.family: Legion S7 15ACH6
dmi.product.name: 82K8
dmi.product.sku: LENOVO_MT_82K8_BU_idea_FM_Legion S7 15ACH6
dmi.product.version: Legion S7 15ACH6
dmi.sys.vendor: LENOVO
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug impish third-party-packages
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https://bugs.launchpad.net/bugs/1944094
Title:
Can't adjust screen backlight on Legion Slim 7 AMD
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