https://lists.ubuntu.com/archives/kernel-team/2021-July/122863.html
-- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-oem-5.10 in Ubuntu. https://bugs.launchpad.net/bugs/1934557 Title: Backlight (screen brightness) on Lenovo P14s AMD Gen2 inop Status in HWE Next: New Status in linux package in Ubuntu: Confirmed Status in linux-oem-5.10 package in Ubuntu: New Status in linux-oem-5.13 package in Ubuntu: New Status in linux-oem-5.10 source package in Focal: New Status in linux-oem-5.13 source package in Focal: New Status in linux source package in Hirsute: New Status in linux source package in Impish: Confirmed Bug description: Backlight does not change. Neither with the keys, nor with the slider. Values in /sys/class/backlight/amdgpu_bl0/brightness do change. However without effect on the actual brightness of the screen, which seems to be stuck at maximum brightness. Following the instructions from here: https://wiki.ubuntu.com/Kernel/Debugging/Backlight ProblemType: Bug DistroRelease: Ubuntu 21.04 Package: linux-image-5.11.0-22-generic 5.11.0-22.23 ProcVersionSignature: Ubuntu 5.11.0-22.23-generic 5.11.21 Uname: Linux 5.11.0-22-generic x86_64 ApportVersion: 2.20.11-0ubuntu65.1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC2: simon 1886 F.... pulseaudio /dev/snd/pcmC2D0p: simon 1886 F...m pulseaudio /dev/snd/controlC1: simon 1886 F.... pulseaudio /dev/snd/controlC0: simon 1886 F.... pulseaudio CasperMD5CheckResult: pass CurrentDesktop: ubuntu:GNOME Date: Sat Jul 3 09:46:53 2021 InstallationDate: Installed on 2021-07-03 (0 days ago) InstallationMedia: Ubuntu 21.04 "Hirsute Hippo" - Release amd64 (20210420) MachineType: LENOVO 21A0CTO1WW ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=de_DE.UTF-8 SHELL=/bin/bash ProcFB: 0 amdgpudrmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-5.11.0-22-generic root=/dev/mapper/vgubuntu-root ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-5.11.0-22-generic N/A linux-backports-modules-5.11.0-22-generic N/A linux-firmware 1.197.1 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 04/23/2021 dmi.bios.release: 1.5 dmi.bios.vendor: LENOVO dmi.bios.version: R1MET35W (1.05 ) dmi.board.asset.tag: Not Available dmi.board.name: 21A0CTO1WW dmi.board.vendor: LENOVO dmi.board.version: Not Defined dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.5 dmi.modalias: dmi:bvnLENOVO:bvrR1MET35W(1.05):bd04/23/2021:br1.5:efr1.5:svnLENOVO:pn21A0CTO1WW:pvrThinkPadP14sGen2a:rvnLENOVO:rn21A0CTO1WW:rvrNotDefined:cvnLENOVO:ct10:cvrNone: dmi.product.family: ThinkPad P14s Gen 2a dmi.product.name: 21A0CTO1WW dmi.product.sku: LENOVO_MT_21A0_BU_Think_FM_ThinkPad P14s Gen 2a dmi.product.version: ThinkPad P14s Gen 2a dmi.sys.vendor: LENOVO ============== SRU justification: [Impact] backlight can't be controlled on AMD platform. [Fix] AUX doesn't work on HDR panel, fallback to PWM mode to make backlight be controlled. [Test] Verified on hardware, backlight brightness works fine. [Where problems could occur] It may break backlight control on AMD platform. To manage notifications about this bug go to: https://bugs.launchpad.net/hwe-next/+bug/1934557/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
