This seems to also effect the Legion 5 15ach6 (AMD) There are two versions of the legion 5, the 2020 version and the 2021 version. It seems that this issue is fixed on the 2020 version by adding the kernel parameter amdgpu.backlight=0 but I can confirm that this does not fix the issue on the 2021 version, so its likely that the 2021 laptop is suffering from whatever this issue is. I'm guessing that the MUX switch is involved in one way or another, as it means that the NVIDIA dGPU does not have to pass frames through the AMD iGPU, it connects to the display separately, and I'm not sure which GPU actually has control over the brightness control. I wonder if the brightness isn't tied to either GPU, maybe its a separate system entirely?
** Summary changed: - Can't adjust screen backlight on Legion Slim 7 AMD + Can't adjust screen backlight on Legion Slim 7 / Legion 5 (2021) AMD -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1944094 Title: Can't adjust screen backlight on Legion Slim 7 / Legion 5 (2021) AMD Status in linux package in Ubuntu: Confirmed Bug description: 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 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1944094/+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
