[Bug 2163249] Re: [i915] Internal display extremely dim despite max backlight, unrelated to DE/kernel version (WhiskeyLake UHD 620)

*** 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/2163249 Title: [i915] Internal display extremely dim despite max backlight, unrelated to DE/kernel version (WhiskeyLake UHD 620) Status in linux package in Ubuntu: Fix Committed Bug description: After a recent update, the internal display (3072x1728 panel) is extremely dark, even though brightness is set to maximum. External monitor is unaffected and normal. Confirmed: - BIOS screen and LUKS decryption prompt are normal brightness (before i915 loads) - Screen becomes dark as soon as i915/GNOME Shell/GDM takes over - Both kernel 7.0.0-27-generic and 7.0.0-29-generic affected equally - Reproduced under GNOME (Wayland), Ubuntu session (Wayland), and XFCE (X11) - all equally dark - /sys/class/backlight/intel_backlight/actual_brightness and brightness both show 1023/1023 (max) - Backlight responds proportionally to manual writes (dims correctly at low values) but never reaches full brightness even at max - Tried kernel params: i915.invert_brightness=1, acpi_backlight=native/vendor, i915.enable_dpcd_backlight=1 - none resolved it - DMC firmware loads without error (kbl_dmc_ver1_04.bin) - No recent BIOS/firmware update (fwupdmgr get-history shows nothing) Hardware: Dell Latitude 7400, Intel WhiskeyLake-U GT2 [UHD Graphics 620] 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: buschra 5550 F.... wireplumber /dev/snd/seq: buschra 5534 F.... pipewire CasperMD5CheckResult: pass CurrentDesktop: ubuntu:GNOME Date: Tue Aug 11 16:27:54 2026 InstallationDate: Installed on 2026-06-08 (64 days ago) InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1) MachineType: Dell Inc. Latitude 7400 ProcEnviron: LANG=de_DE.UTF-8 PATH=(custom, no user) SHELL=/bin/bash TERM=xterm-256color XDG_RUNTIME_DIR=<set> ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-29-generic root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash i915.invert_brightness=1 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: 08/28/2025 dmi.bios.release: 1.42 dmi.bios.vendor: Dell Inc. dmi.bios.version: 1.42.1 dmi.board.name: 07WDVW dmi.board.vendor: Dell Inc. dmi.board.version: A01 dmi.chassis.type: 10 dmi.chassis.vendor: Dell Inc. dmi.modalias: dmi:bvnDellInc.:bvr1.42.1:bd08/28/2025:br1.42:svnDellInc.:pnLatitude7400:pvr:rvnDellInc.:rn07WDVW:rvrA01:cvnDellInc.:ct10:cvr:sku08E1:pfaLatitude: dmi.product.family: Latitude dmi.product.name: Latitude 7400 dmi.product.sku: 08E1 dmi.sys.vendor: Dell Inc. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2163249/+subscriptions