[Bug 2163269] Re: Blackscreen and no brightness dimming after update

*** This bug is a duplicate of bug 2161309 *** https://bugs.launchpad.net/bugs/2161309 ** This bug has been marked a duplicate of bug 2161309 Backlight regression -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2163269 Title: Blackscreen and no brightness dimming after update Status in linux package in Ubuntu: Confirmed Bug description: Since the update two weeks ago, i was not able to dimm the brightness of my T480 screen any more. In addition, the backlight was not working any more after suspend. I was able to fix that bug for me, by adding i915.enable_dpcd_backlight=0 to grub. Hope this helps to make it run again on other systems :) Description: Ubuntu 26.04 LTS Release: 26.04 Using KDE from the Kubuntu Repo ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-29-generic 7.0.0-29.29 ProcVersionSignature: Ubuntu 7.0.0-29.29-generic 7.0.12 Uname: Linux 7.0.0-29-generic x86_64 ApportVersion: 2.34.1-0ubuntu0.1 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: leon 3208 F.... wireplumber /dev/snd/seq: leon 3193 F.... pipewire CasperMD5CheckResult: unknown CurrentDesktop: KDE Date: Tue Aug 11 21:11:07 2026 InstallationDate: Installed on 2025-02-24 (533 days ago) InstallationMedia: Kubuntu 24.10 "Oracular Oriole" - Release amd64 (20241007.6) MachineType: LENOVO 20L6S69B00 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-7.0.0-29-generic root=UUID=479d0569-3f49-4684-81d5-e523668c3705 ro rootflags=subvol=@ quiet splash i915.enable_dpcd_backlight=0 crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. SourcePackage: linux UpgradeStatus: Upgraded to resolute on 2026-04-27 (106 days ago) dmi.bios.date: 09/06/2025 dmi.bios.release: 1.56 dmi.bios.vendor: LENOVO dmi.bios.version: N24ET81W (1.56 ) dmi.board.asset.tag: Not Available dmi.board.name: 20L6S69B00 dmi.board.vendor: LENOVO dmi.board.version: SDK0J40697 WIN dmi.chassis.asset.tag: No Asset Information dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: None dmi.ec.firmware.release: 1.22 dmi.modalias: dmi:bvnLENOVO:bvrN24ET81W(1.56):bd09/06/2025:br1.56:efr1.22:svnLENOVO:pn20L6S69B00:pvrThinkPadT480:rvnLENOVO:rn20L6S69B00:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20L6_BU_Think_FM_ThinkPadT480:pfaThinkPadT480: dmi.product.family: ThinkPad T480 dmi.product.name: 20L6S69B00 dmi.product.sku: LENOVO_MT_20L6_BU_Think_FM_ThinkPad T480 dmi.product.version: ThinkPad T480 dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2163269/+subscriptions