After rereading everything and going over the provided data, It seems this isn't a kernel issue.
In the wiki article about debugging backlights (https://wiki.ubuntu.com/Kernel/Debugging/Backlight) the first bullet point says: Hotkeys change the brightness, but no OSD feedback and the brightness applet does not work. There is nothing that the kernel can do to resolve this situation. Since there is no vendor specific control mechanism and the generic ACPI interface is not defined (or not defined correctly), there is no way Linux can interact. In those cases the hotkeys are directly wired to the backlight control and no events are passed on to the OS. And it seems your hotkeys do work to change the brightness. I'm not sure if the info in this page will be helpful, but it is worth trying these suggestions: https://help.ubuntu.com/community/ScreenBacklight ** Changed in: linux (Ubuntu) Status: New => Invalid -- 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/2076466 Title: I am unable to change the backlight on my ASUS PT2001 All In One computer Status in linux package in Ubuntu: Invalid Bug description: I am unable to change the backlight on my ASUS PT2001 All In One Computer. I have followed all of the directions in this (https://wiki.ubuntu.com/Kernel/Debugging/Backlight) debugging article, but at no point was any directory displayed under /sys/class/backlight. Likewise I was unable to change the backlight brightness using the brightness applet. The issue persisted no matter the kernel options I specified on boot. The computer does have hardware keys built into it that control an On Screen Display that is able to change the backlight intensity. I will attempt to attach all of the uncompressed files generated when following the debug steps. ProblemType: Bug DistroRelease: Ubuntu 24.04 Package: linux-image-6.8.0-40-generic 6.8.0-40.40 ProcVersionSignature: Ubuntu 6.8.0-40.40-generic 6.8.12 Uname: Linux 6.8.0-40-generic x86_64 ApportVersion: 2.28.1-0ubuntu3 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/seq: lucas 1077 F.... pipewire /dev/snd/controlC0: lucas 1079 F.... wireplumber /dev/snd/controlC1: lucas 1079 F.... wireplumber CRDA: N/A CasperMD5CheckResult: unknown CurrentDesktop: LXQt Date: Fri Aug 9 17:01:57 2024 InstallationDate: Installed on 2024-08-02 (7 days ago) InstallationMedia: Lubuntu 24.04 LTS "Noble Numbat" - Release amd64 (20240425.1) MachineType: ASUSTeK Computer INC. PT2001 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-40-generic root=UUID=ae873e6a-2261-439b-a6fd-d27fafb11175 ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-6.8.0-40-generic N/A linux-backports-modules-6.8.0-40-generic N/A linux-firmware 20240318.git3b128b60-0ubuntu2.1 SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 11/07/2014 dmi.bios.release: 4.6 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 0802 dmi.board.asset.tag: To be filled by O.E.M. dmi.board.name: PT2001 dmi.board.vendor: ASUSTeK COMPUTER INC. dmi.board.version: To be filled by O.E.M. dmi.chassis.asset.tag: To Be Filled By O.E.M. dmi.chassis.type: 10 dmi.chassis.vendor: To Be Filled By O.E.M. dmi.chassis.version: To Be Filled By O.E.M. dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0802:bd11/07/2014:br4.6:svnASUSTeKComputerINC.:pnPT2001:pvr0802:rvnASUSTeKCOMPUTERINC.:rnPT2001:rvrTobefilledbyO.E.M.:cvnToBeFilledByO.E.M.:ct10:cvrToBeFilledByO.E.M.:skuSKU: dmi.product.family: All-In-One dmi.product.name: PT2001 dmi.product.sku: SKU dmi.product.version: 0802 dmi.sys.vendor: ASUSTeK Computer INC. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2076466/+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
