Public bug reported:
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.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
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Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2163249
Title:
[i915] Internal display extremely dim despite max backlight, unrelated
to DE/kernel version (WhiskeyLake UHD 620)
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