[Bug 2161739] [NEW] Backlight brightness no longer works on Fujitsu LIFEBOOK P727 with Intel HD 620 after upgrading to Linux 7.0.0-28

Public bug reported: After upgrading from Linux 7.0.0-27 to 7.0.0-28, the LCD backlight can no longer be adjusted. Laptop: Fujitsu LIFEBOOK P727 GPU: Intel HD Graphics 620 (Kaby Lake-U) Kubuntu 26.04 LTS /sys/class/backlight/intel_backlight/brightness and actual_brightness both change correctly. The physical display brightness never changes. KDE brightness slider and keyboard brightness keys also stop working. Booting back into Linux 7.0.0-27 immediately restores correct brightness control. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-28-generic 7.0.0-28.28 ProcVersionSignature: Ubuntu 7.0.0-28.28-generic 7.0.12 Uname: Linux 7.0.0-28-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: irfan 1619 F.... wireplumber /dev/snd/seq: irfan 1612 F.... pipewire CasperMD5CheckResult: pass CurrentDesktop: KDE Date: Fri Jul 24 19:38:24 2026 InstallationDate: Installed on 2025-11-19 (247 days ago) InstallationMedia: Kubuntu 22.04.5 LTS "Jammy Jellyfish" - Release amd64 (20240911) MachineType: FUJITSU LIFEBOOK P727 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-28-generic root=UUID=5fd1e762-85e1-40ff-98a2-4cd01ee9a8ab ro quiet splash 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 2026-06-06 (48 days ago) dmi.bios.date: 02/10/2025 dmi.bios.release: 1.29 dmi.bios.vendor: FUJITSU // Insyde Software Corp. dmi.bios.version: Version 1.29 dmi.board.name: FJNB2A9 dmi.board.vendor: FUJITSU dmi.board.version: G3 dmi.chassis.asset.tag: 3000000989 dmi.chassis.type: 31 dmi.chassis.vendor: FUJITSU dmi.chassis.version: LIFEBOOK P727 dmi.modalias: dmi:bvnFUJITSU//InsydeSoftwareCorp.:bvrVersion1.29:bd02/10/2025:br1.29:svnFUJITSU:pnLIFEBOOKP727:pvr10601736746:rvnFUJITSU:rnFJNB2A9:rvrG3:cvnFUJITSU:ct31:cvrLIFEBOOKP727:skuSK01:pfaLIFEBOOK-FTS: dmi.product.family: LIFEBOOK-FTS dmi.product.name: LIFEBOOK P727 dmi.product.sku: SK01 dmi.product.version: 10601736746 dmi.sys.vendor: FUJITSU ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug resolute wayland-session -- You received this bug notification because you are subscribed to linux in Ubuntu. Matching subscriptions: Bgg, Bmail, Nb https://bugs.launchpad.net/bugs/2161739 Title: Backlight brightness no longer works on Fujitsu LIFEBOOK P727 with Intel HD 620 after upgrading to Linux 7.0.0-28 Status in linux package in Ubuntu: New Bug description: After upgrading from Linux 7.0.0-27 to 7.0.0-28, the LCD backlight can no longer be adjusted. Laptop: Fujitsu LIFEBOOK P727 GPU: Intel HD Graphics 620 (Kaby Lake-U) Kubuntu 26.04 LTS /sys/class/backlight/intel_backlight/brightness and actual_brightness both change correctly. The physical display brightness never changes. KDE brightness slider and keyboard brightness keys also stop working. Booting back into Linux 7.0.0-27 immediately restores correct brightness control. ProblemType: Bug DistroRelease: Ubuntu 26.04 Package: linux-image-7.0.0-28-generic 7.0.0-28.28 ProcVersionSignature: Ubuntu 7.0.0-28.28-generic 7.0.12 Uname: Linux 7.0.0-28-generic x86_64 ApportVersion: 2.34.0-0ubuntu2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC0: irfan 1619 F.... wireplumber /dev/snd/seq: irfan 1612 F.... pipewire CasperMD5CheckResult: pass CurrentDesktop: KDE Date: Fri Jul 24 19:38:24 2026 InstallationDate: Installed on 2025-11-19 (247 days ago) InstallationMedia: Kubuntu 22.04.5 LTS "Jammy Jellyfish" - Release amd64 (20240911) MachineType: FUJITSU LIFEBOOK P727 ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-28-generic root=UUID=5fd1e762-85e1-40ff-98a2-4cd01ee9a8ab ro quiet splash 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 2026-06-06 (48 days ago) dmi.bios.date: 02/10/2025 dmi.bios.release: 1.29 dmi.bios.vendor: FUJITSU // Insyde Software Corp. dmi.bios.version: Version 1.29 dmi.board.name: FJNB2A9 dmi.board.vendor: FUJITSU dmi.board.version: G3 dmi.chassis.asset.tag: 3000000989 dmi.chassis.type: 31 dmi.chassis.vendor: FUJITSU dmi.chassis.version: LIFEBOOK P727 dmi.modalias: dmi:bvnFUJITSU//InsydeSoftwareCorp.:bvrVersion1.29:bd02/10/2025:br1.29:svnFUJITSU:pnLIFEBOOKP727:pvr10601736746:rvnFUJITSU:rnFJNB2A9:rvrG3:cvnFUJITSU:ct31:cvrLIFEBOOKP727:skuSK01:pfaLIFEBOOK-FTS: dmi.product.family: LIFEBOOK-FTS dmi.product.name: LIFEBOOK P727 dmi.product.sku: SK01 dmi.product.version: 10601736746 dmi.sys.vendor: FUJITSU To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2161739/+subscriptions