Public bug reported:
I am experiencing several related display and suspend/resume problems on
Ubuntu on a Dell Latitude 5490.
### 1. Brightness control
The internal display brightness cannot be controlled correctly. The
normal brightness controls do not change the brightness as expected.
The problem appears to be related to the internal display backlight
rather than simply the desktop brightness controls.
### 2. Suspend when closing the lid
When I close the laptop lid, the system does not reliably enter
suspend/sleep mode as expected.
### 3. Resume from suspend with the internal display
If the laptop does enter suspend, it does not reliably wake up
correctly. In some cases the system appears to resume, but the internal
display/backlight remains off, leaving me unable to use the laptop
normally.
### 4. Resume from suspend with an external monitor
The problem is worse when an external monitor is connected.
If the laptop enters suspend while connected to an external monitor, it
may fail to wake up at all. The external monitor does not recover the
display, and the laptop becomes effectively unusable until I force a
reboot/power cycle.
### Expected behavior
* The brightness keys/settings should correctly control the internal display
brightness.
* Closing the lid should put the laptop into suspend.
* The laptop should reliably resume from suspend.
* The internal display should restore its backlight after resume.
* Suspend/resume should work correctly when an external monitor is connected.
### Actual behavior
Brightness control is not functional, lid-close suspend is unreliable,
and suspend/resume can fail completely. When the internal display
backlight is involved, the machine can appear to resume without
restoring the display. With an external monitor connected, resume can
fail completely.
This happens on a Dell Latitude 5490 running Ubuntu.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: xorg 1:7.7+23ubuntu3
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
BootLog: Error: [Errno 13] Permission denied: '/var/log/boot.log'
CasperMD5CheckResult: unknown
CompositorRunning: None
CurrentDesktop: ubuntu:GNOME
Date: Sun Aug 9 11:50:33 2026
DistUpgraded: Fresh install
DistroCodename: noble
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes, including running git bisection searches
GraphicsCard:
Intel Corporation UHD Graphics 620 [8086:5917] (rev 07) (prog-if 00 [VGA
controller])
Subsystem: Dell UHD Graphics 620 [1028:0816]
MachineType: Dell Inc. Latitude 5490
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-7.0.0-28-generic
root=UUID=ef72dc3a-b544-4316-9fda-f6aba5dd007c ro quiet splash
acpi_backlight=vendor vt.handoff=7
SourcePackage: xorg
Symptom: display
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 11/06/2024
dmi.bios.release: 1.38
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.38.0
dmi.board.name: 08NJ82
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvr1.38.0:bd11/06/2024:br1.38:svnDellInc.:pnLatitude5490:pvr:rvnDellInc.:rn08NJ82:rvrA00:cvnDellInc.:ct10:cvr:sku0816:pfaLatitude:
dmi.product.family: Latitude
dmi.product.name: Latitude 5490
dmi.product.sku: 0816
dmi.sys.vendor: Dell Inc.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.125-1ubuntu0.1~24.04.2
version.libgl1-mesa-dri: libgl1-mesa-dri 25.2.8-0ubuntu0.24.04.2
version.libgl1-mesa-glx: libgl1-mesa-glx 23.0.4-0ubuntu1~22.04.1
version.xserver-xorg-core: xserver-xorg-core 2:21.1.12-1ubuntu1.6
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:22.0.0-1build1
version.xserver-xorg-video-intel: xserver-xorg-video-intel
2:2.99.917+git20210115-1build1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau
1:1.0.17-2ubuntu0.1
** Affects: ubuntu
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble ubuntu
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https://bugs.launchpad.net/bugs/2163111
Title:
Dell Latitude 5490: brightness control broken and suspend/resume
fails, especially with external monitor
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