Re: [Bug 2161309] Re: Backlight regression

Ohh I wanted to inform the necessary parties that I was able to fix my earlier started issue. Thanks for the feedback On Wed, 19 Aug 2026 at 19:01, Krystian Kaniewski <2161309@bugs.launchpad.net> wrote: > ** Also affects: linux (Ubuntu Resolute) > Importance: Undecided > Status: New > > ** Also affects: linux-hwe-7.0 (Ubuntu Resolute) > Importance: Undecided > Status: New > > ** Also affects: linux (Ubuntu Noble) > Importance: Undecided > Status: New > > ** Also affects: linux-hwe-7.0 (Ubuntu Noble) > Importance: Undecided > Status: New > > ** Changed in: linux (Ubuntu Resolute) > Status: New => Fix Committed > > ** Changed in: linux (Ubuntu Resolute) > Assignee: (unassigned) => Krystian Kaniewski (kkaniewski) > > ** Changed in: linux-hwe-7.0 (Ubuntu Noble) > Status: New => Fix Committed > > ** Changed in: linux-hwe-7.0 (Ubuntu Noble) > Importance: Undecided => Critical > > ** Changed in: linux-hwe-7.0 (Ubuntu Noble) > Assignee: (unassigned) => Krystian Kaniewski (kkaniewski) > > ** Changed in: linux (Ubuntu Noble) > Status: New => Invalid > > ** Changed in: linux-hwe-7.0 (Ubuntu Resolute) > Status: New => Invalid > > ** Changed in: linux (Ubuntu Noble) > Assignee: (unassigned) => Krystian Kaniewski (kkaniewski) > > ** Changed in: linux-hwe-7.0 (Ubuntu Resolute) > Assignee: (unassigned) => Krystian Kaniewski (kkaniewski) > > ** Changed in: linux (Ubuntu Resolute) > Importance: Undecided => Critical > > ** Changed in: linux (Ubuntu Resolute) > Importance: Critical => High > > ** Changed in: linux-hwe-7.0 (Ubuntu Noble) > Importance: Critical => High > > -- > You received this bug notification because you are subscribed to a > duplicate bug report (2163479). > https://bugs.launchpad.net/bugs/2161309 > > Title: > Backlight regression > > Status in linux package in Ubuntu: > Fix Committed > Status in linux-hwe-7.0 package in Ubuntu: > Fix Committed > Status in linux source package in Noble: > Invalid > Status in linux-hwe-7.0 source package in Noble: > Fix Committed > Status in linux source package in Resolute: > Fix Committed > Status in linux-hwe-7.0 source package in Resolute: > Invalid > > Bug description: > ----------------------------- > > Possible workaround until 7.0.0-31 kernel is released > Boot with i915.enable_dpcd_backlight=0 parameter > > ----------------------------- > > > ThinkPad T480 > Intel UHD 620 > brightness works on 7.0.0-27 > brightness fails on 7.0.0-28 > /sys/class/backlight/intel_backlight changes but panel does not > > ProblemType: Bug > DistroRelease: Ubuntu 26.04 > Package: linux-image-7.0.0-27-generic 7.0.0-27.27 > ProcVersionSignature: Ubuntu 7.0.0-27.27-generic 7.0.6 > Uname: Linux 7.0.0-27-generic x86_64 > ApportVersion: 2.34.0-0ubuntu2 > Architecture: amd64 > AudioDevicesInUse: > USER PID ACCESS COMMAND > /dev/snd/controlC0: neal 3608 F.... wireplumber > /dev/snd/seq: neal 3589 F.... pipewire > CasperMD5CheckResult: unknown > CurrentDesktop: ubuntu:GNOME > Date: Mon Jul 20 12:47:12 2026 > InstallationDate: Installed on 2026-07-12 (8 days ago) > InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 > (20260423.1) > MachineType: LENOVO 20L6S6L601 > ProcFB: 0 i915drmfb > ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-27-generic > root=UUID=1cea3fcd-0665-4cb4-a85a-4ebc58d5aed0 ro quiet splash > acpi_backlight=native > crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M > SourcePackage: linux > UpgradeStatus: No upgrade log present (probably fresh install) > 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: 20L6S6L601 > 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:pn20L6S6L601:pvrThinkPadT480:rvnLENOVO:rn20L6S6L601:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20L6_BU_Think_FM_ThinkPadT480:pfaThinkPadT480: > dmi.product.family: ThinkPad T480 > dmi.product.name: 20L6S6L601 > 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/2161309/+subscriptions > > -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161309 Title: Backlight regression Status in linux package in Ubuntu: Fix Committed Status in linux-hwe-7.0 package in Ubuntu: Fix Committed Status in linux source package in Noble: Invalid Status in linux-hwe-7.0 source package in Noble: Fix Committed Status in linux source package in Resolute: Fix Committed Status in linux-hwe-7.0 source package in Resolute: Invalid Bug description: ----------------------------- Possible workaround until 7.0.0-31 kernel is released Boot with i915.enable_dpcd_backlight=0 parameter ----------------------------- ThinkPad T480 Intel UHD 620 brightness works on 7.0.0-27 brightness fails on 7.0.0-28 /sys/class/backlight/intel_backlight changes but panel does not ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-27-generic 7.0.0-27.27 ProcVersionSignature: Ubuntu 7.0.0-27.27-generic 7.0.6 Uname: Linux 7.0.0-27-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 AudioDevicesInUse:  USER PID ACCESS COMMAND  /dev/snd/controlC0: neal 3608 F.... wireplumber  /dev/snd/seq: neal 3589 F.... pipewire CasperMD5CheckResult: unknown CurrentDesktop: ubuntu:GNOME Date: Mon Jul 20 12:47:12 2026 InstallationDate: Installed on 2026-07-12 (8 days ago) InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1) MachineType: LENOVO 20L6S6L601 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-27-generic root=UUID=1cea3fcd-0665-4cb4-a85a-4ebc58d5aed0 ro quiet splash acpi_backlight=native crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) 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: 20L6S6L601 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:pn20L6S6L601:pvrThinkPadT480:rvnLENOVO:rn20L6S6L601:rvrSDK0J40697WIN:cvnLENOVO:ct10:cvrNone:skuLENOVO_MT_20L6_BU_Think_FM_ThinkPadT480:pfaThinkPadT480: dmi.product.family: ThinkPad T480 dmi.product.name: 20L6S6L601 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/2161309/+subscriptions