[Bug 2161309] Re: Backlight regression

Hi guys, I have tested the proposed kernel on my system and can confirm that the regression is fixed. Hardware & System Details: - Device: Dell Precision M4800 - OS: Ubuntu 26.04 LTS - Graphics: Hybrid / Dual GPU (Intel HD Graphics + NVIDIA Quadro K1100M on nouveau) - Tested Kernel Version: linux-image-7.0.0-31-generic (7.0.0-31.31) from -proposed Test Results: 1. Backlight / Brightness Regulation: Works properly via Fn keyboard shortcuts as well as the GUI slider. 2. Suspend & Resume: The black screen issue is completely resolved. Upon waking from suspend, the screen backlight turns back on immediately. Thank you for fixing this issue! ***** PS, Just as an aside note: AI was very helpful - guide how to install linux-image-7.0.0-31-generic https://aistudio.google.com/ 2 minutes for me -- 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