This problem seems to persist on Ubuntu 20.10. The workaround is using an "external" app. > sudo apt install brightness-controller
Probably this a nvidia related issue. Opening the Nvidia configuration app resets to max brightness. -- 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/1863407 Title: Lenovo Ideapad L340 screen backlight stuck at maximum brightness Status in linux package in Ubuntu: Expired Bug description: acpi_osi=Linux and acpi_backlight=vendor do not fix. Depending on the kernel parameters, /sys/class/backlight contains either "acpi_video0" or "ideapad". I have also tried acpi_backlight=none ls /sys/class/backlight: acpi_video0 grep -r . /proc/acpi /proc/acpi/button/lid/LID/state:state: open /proc/acpi/wakeup:Device S-state Status Sysfs node /proc/acpi/wakeup:GPP0 S3 *disabled /proc/acpi/wakeup:GPP1 S3 *enabled pci:0000:00:01.2 /proc/acpi/wakeup:GPP2 S3 *enabled pci:0000:00:01.3 /proc/acpi/wakeup:GPP3 S3 *disabled /proc/acpi/wakeup:GPP4 S3 *disabled /proc/acpi/wakeup:GPP5 S3 *disabled /proc/acpi/wakeup:GPP6 S3 *disabled /proc/acpi/wakeup:GP17 S3 *enabled pci:0000:00:08.1 /proc/acpi/wakeup:XHC0 S3 *enabled pci:0000:03:00.3 /proc/acpi/wakeup:XHC1 S3 *enabled pci:0000:03:00.4 /proc/acpi/wakeup:GP18 S3 *enabled pci:0000:00:08.2 iasl -d dsdt.dat Intel ACPI Component Architecture ASL+ Optimizing Compiler/Disassembler version 20180105 Copyright (c) 2000 - 2018 Intel Corporation Input file dsdt.dat, Length 0x6FA5 (28581) bytes ACPI: DSDT 0x0000000000000000 006FA5 (v01 LENOVO AMD 00001000 INTL 20120711) Pass 1 parse of [DSDT] Pass 2 parse of [DSDT] Parsing Deferred Opcodes (Methods/Buffers/Packages/Regions) Parsing completed Found 6 external control methods, reparsing with new information Pass 1 parse of [DSDT] Pass 2 parse of [DSDT] Parsing Deferred Opcodes (Methods/Buffers/Packages/Regions) Parsing completed Disassembly completed ASL Output: dsdt.dsl - 318645 bytes iASL Warning: There were 6 external control methods found during disassembly, but only 0 were resolved (6 unresolved). Additional ACPI tables may be required to properly disassemble the code. This resulting disassembler output file may not compile because the disassembler did not know how many arguments to assign to the unresolved methods. Note: SSDTs can be dynamically loaded at runtime and may or may not be available via the host OS. To specify the tables needed to resolve external control method references, the -e option can be used to specify the filenames. Example iASL invocations: iasl -e ssdt1.aml ssdt2.aml ssdt3.aml -d dsdt.aml iasl -e dsdt.aml ssdt2.aml -d ssdt1.aml iasl -e ssdt*.aml -d dsdt.aml In addition, the -fe option can be used to specify a file containing control method external declarations with the associated method argument counts. Each line of the file must be of the form: External (<method pathname>, MethodObj, <argument count>) Invocation: iasl -fe refs.txt -d dsdt.aml ProblemType: Bug DistroRelease: Ubuntu 18.04 Package: linux-image-4.15.0-76-generic 4.15.0-76.86 ProcVersionSignature: Ubuntu 4.15.0-76.86-generic 4.15.18 Uname: Linux 4.15.0-76-generic x86_64 ApportVersion: 2.20.9-0ubuntu7.9 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: eli 1603 F.... pulseaudio /dev/snd/controlC0: eli 1603 F.... pulseaudio CurrentDesktop: ubuntu:GNOME Date: Sat Feb 15 01:51:30 2020 InstallationDate: Installed on 2020-01-30 (15 days ago) InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725) MachineType: LENOVO 81LY ProcEnviron: TERM=xterm-256color PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 EFI VGA ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.15.0-76-generic root=UUID=97a5f239-2442-42e1-a2c8-b7bf4985a13a ro quiet splash vt.handoff=1 RelatedPackageVersions: linux-restricted-modules-4.15.0-76-generic N/A linux-backports-modules-4.15.0-76-generic N/A linux-firmware 1.173.14 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 10/28/2019 dmi.bios.vendor: LENOVO dmi.bios.version: ARCN33WW dmi.board.asset.tag: No Asset Tag dmi.board.name: LNVNB161216 dmi.board.vendor: LENOVO dmi.board.version: SDK0J40700WIN dmi.chassis.asset.tag: No Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Lenovo IdeaPad L340-17API dmi.modalias: dmi:bvnLENOVO:bvrARCN33WW:bd10/28/2019:svnLENOVO:pn81LY:pvrLenovoIdeaPadL340-17API:rvnLENOVO:rnLNVNB161216:rvrSDK0J40700WIN:cvnLENOVO:ct10:cvrLenovoIdeaPadL340-17API: dmi.product.family: IdeaPad L340-17API dmi.product.name: 81LY dmi.product.version: Lenovo IdeaPad L340-17API dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1863407/+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
