Can't control display backlight in 24.04 on Dell AIO system

[heynnema]

Ubuntu 23.10/24.04
Dell Inspiron 7700 AIO
6.5.0-35-generic/6.8.0-31-generic
X11

https://askubuntu.com/questions/1514988/backlight-brightness-not-working-in-ubuntu-23-10-24-04-on-dell-7700-aio

lsb_release -rd
No LSB modules are available.
Description: Ubuntu 24.04 LTS
Release: 24.04

dell_uart_backlight kernel driver isn't in the 24.04 distribution, so NO Dell AIO display backlights can be adjusted. No brightness slider appears. (dell_uart_backlight is in the 23.10 distribution, but backlight/brightness slider control doesn't work 100% properly).

Works fine in 23.04.

dup: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2067497

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.8.0-31-generic 6.8.0-31.31
ProcVersionSignature: Ubuntu 6.8.0-31.31-generic 6.8.1
Uname: Linux 6.8.0-31-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.28.1-0ubuntu3
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/seq: al 3689 F.... pipewire
 /dev/snd/controlC1: al 3696 F.... wireplumber
 /dev/snd/controlC0: al 3696 F.... wireplumber
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed May 29 08:32:16 2024
InstallationDate: Installed on 2021-09-25 (978 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-6.8.0-31-generic root=UUID=f0db2226-e28d-46dd-9b5a-457c87987ed2 ro quiet splash ipv6.disable=1 acpi_backlight=vendor acpi_osi=Linux vt.handoff=7
RelatedPackageVersions:
 linux-restricted-modules-6.8.0-31-generic N/A
 linux-backports-modules-6.8.0-31-generic N/A
 linux-firmware 20240318.git3b128b60-0ubuntu2
SourcePackage: linux
UpgradeStatus: Upgraded to noble on 2024-05-25 (4 days ago)
dmi.bios.date: 03/27/2024
dmi.bios.release: 1.28
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.28.0
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.:bvr1.28.0:bd03/27/2024:br1.28: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.