Public bug reported:
Dell Inspiron 7700 AIO
Ubuntu 25.10
With the latest kernel updates (6.17.0-8 and 6.17.0-7) the brightness
control has disappeared (again). It was missing for quite some time, but
then it reappeared with about kernel 6.17.0-6.
In looking in /sys/class/backlight I do see this:
ls -al /sys/class/backlight
drwxr-xr-x 2 root root 0 Dec 10 01:12 ./
drwxr-xr-x 85 root root 0 Dec 10 01:12 ../
lrwxrwxrwx 1 root root 0 Dec 10 2025 dell_uart_backlight@ ->
../../devices/pnp0/00:01/00:01:0/00:01:0.0/serial0/serial0-0/backlight/dell_uart_backlight
And this looks normal.
In looking at the Dell-specific kernel modules loaded, I see:
lsmod|grep -i dell
dell_wmi 28672 0
dell_smbios 36864 1 dell_wmi
dcdbas 20480 1 dell_smbios
dell_uart_backlight 20480 0
dell_smm_hwmon 36864 0
dell_wmi_sysman 49152 0
dell_wmi_aio 12288 0
dell_wmi_descriptor 20480 2 dell_wmi,dell_smbios
firmware_attributes_class 12288 1 dell_wmi_sysman
sparse_keymap 12288 2 dell_wmi,dell_wmi_aio
video 77824 5
dell_uart_backlight,dell_wmi,xe,i915,nvidia_modeset
wmi 28672 9
dell_wmi_sysman,video,dell_wmi,dell_wmi_aio,wmi_bmof,dell_smm_hwmon,dell_smbios,dell_wmi_descriptor,mxm_wmi
The Dell AIO (All-in-One) computers control their brightness via a
special UART chip.
ProblemType: Bug
DistroRelease: Ubuntu 25.10
Package: linux-image-6.17.0-8-generic 6.17.0-8.8
ProcVersionSignature: Ubuntu 6.17.0-8.8-generic 6.17.2
Uname: Linux 6.17.0-8-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.33.1-0ubuntu3
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: al 4237 F.... wireplumber
/dev/snd/controlC1: al 4237 F.... wireplumber
/dev/snd/seq: al 4216 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Dec 10 08:38:55 2025
InstallationDate: Installed on 2021-09-25 (1538 days ago)
InstallationMedia: Ubuntu 21.04 "Hirsute Hippo" - Release amd64 (20210420)
MachineType: Dell Inc. Inspiron 7700 AIO
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.17.0-8-generic
root=UUID=f0db2226-e28d-46dd-9b5a-457c87987ed2 ro quiet splash ipv6.disable=1
acpi_osi=Linux
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
vt.handoff=7
RelatedPackageVersions:
firmware-sof N/A
linux-firmware 20250901.git993ff19b-0ubuntu1.4
SourcePackage: linux
UpgradeStatus: Upgraded to questing on 2025-10-31 (40 days ago)
dmi.bios.date: 08/05/2025
dmi.bios.release: 1.39
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.39.0
dmi.board.name: 0K9T56
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 13
dmi.chassis.vendor: Dell Inc.
dmi.modalias:
dmi:bvnDellInc.:bvr1.39.0:bd08/05/2025:br1.39:svnDellInc.:pnInspiron7700AIO:pvr:rvnDellInc.:rn0K9T56:rvrA00:cvnDellInc.:ct13:cvr:sku0A07:
dmi.product.family: Inspiron
dmi.product.name: Inspiron 7700 AIO
dmi.product.sku: 0A07
dmi.sys.vendor: Dell Inc.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug questing wayland-session
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https://bugs.launchpad.net/bugs/2134555
Title:
Brightness control missing (again) on Dell AIO
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