Public bug reported:
# Regression: Dell Latitude 7390 internal panel becomes extremely dim
with Linux 7.0.0-28
## Summary
After upgrading to Linux kernel **7.0.0-28-generic** on Ubuntu 24.04.4
LTS, the internal LCD panel becomes extremely dim immediately after the
Dell logo disappears and the Linux kernel takes control.
The display contents remain perfectly visible, but the backlight appears
to be reduced to approximately 5% even though Linux reports maximum
brightness.
Booting the previous kernel **6.17.0-35-generic** restores normal
brightness.
This is a reproducible regression.
## Hardware
* Dell Latitude 7390
* BIOS: 1.44.0 (2025-08-04)
* Intel UHD Graphics 620
* PCI ID: 8086:5917
* Subsystem: Dell 1028:081b
* Kernel driver: i915
Internal display:
* AU Optronics B133HAK
* 13.3" eDP
* 1920×1080
## Software
Ubuntu 24.04.4 LTS
Working kernel:
* Linux 6.17.0-35-generic
Broken kernel:
* Linux 7.0.0-28-generic
## Symptoms
Immediately after the firmware hands control to the Linux kernel, the
internal LCD becomes extremely dim.
The desktop remains fully visible.
This is **not** a black screen and the GPU continues to operate
normally.
Windows boots with normal brightness.
Ubuntu Recovery Mode also boots with normal brightness.
Booting kernel 6.17.0-35 restores normal brightness.
## Backlight information
The system exposes only:
```
/sys/class/backlight/intel_backlight
```
Brightness values are:
```
brightness = 1023
max_brightness = 1023
```
Therefore Linux believes the panel is already at maximum brightness.
systemd-backlight restores the saved brightness successfully.
## Kernel parameters tested
No improvement with:
```
i915.enable_psr=0
i915.enable_dc=0
intel_idle.max_cstate=1
```
## Driver information
GPU:
```
Intel UHD Graphics 620 [8086:5917]
```
Kernel driver:
```
i915
```
No obvious DRM or i915 errors appear in the system journal.
The driver initializes successfully, loads DMC firmware and creates the
DRM framebuffer normally.
## Expected behaviour
Kernel 7.0.0-28 should provide the same panel brightness as kernel
6.17.0-35.
## Actual behaviour
Kernel 7.0.0-28 initializes successfully but the internal eDP panel
becomes extremely dim while software brightness remains at 100%.
This regression is fully reproducible on this hardware.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-7.0.0-28-generic 7.0.0-28.28~24.04.1
ProcVersionSignature: Ubuntu 7.0.0-28.28~24.04.1-generic 7.0.12
Uname: Linux 7.0.0-28-generic x86_64
ApportVersion: 2.28.2-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: arnaud 2550 F.... wireplumber
/dev/snd/seq: arnaud 2545 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Mon Aug 3 14:11:21 2026
InstallationDate: Installed on 2026-04-17 (108 days ago)
InstallationMedia: Ubuntu 24.04.4 LTS "Noble Numbat" - Release amd64 (20260210)
MachineType: Dell Inc. Latitude 7390
ProcEnviron:
LANG=fr_FR.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-28-generic
root=UUID=0792621f-5cca-40af-87ab-6a95adad82df ro quiet splash
i915.enable_psr=0 i915.enable_dc=0 intel_idle.max_cstate=1 vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-7.0.0-28-generic N/A
linux-backports-modules-7.0.0-28-generic N/A
linux-firmware 20240318.git3b128b60-0ubuntu2.27
SourcePackage: linux-hwe-7.0
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 04/08/2025
dmi.bios.release: 1.44
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.44.0
dmi.board.name: 09386V
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvr1.44.0:bd04/08/2025:br1.44:svnDellInc.:pnLatitude7390:pvr:rvnDellInc.:rn09386V:rvrA00:cvnDellInc.:ct10:cvr:sku081B:pfaLatitude:
dmi.product.family: Latitude
dmi.product.name: Latitude 7390
dmi.product.sku: 081B
dmi.sys.vendor: Dell Inc.
** Affects: linux-hwe-7.0 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
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https://bugs.launchpad.net/bugs/2162735
Title:
Regression report: Intel UHD 620 backlight extremely dim with Linux
7.0.0-28 on Dell Latitude 7390
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