Public bug reported:

System

Ubuntu 26.04
Acer Aspire 7 A715-76G
Intel Alder Lake UHD Graphics (8086:46a3)

Regression

Kernel 7.0.0-27: brightness works normally.

Kernel 7.0.0-28: brightness no longer works.

Kernel 7.0.0-29: issue still present.

Observed behavior

Brightness slider moves.
Fn brightness keys do not affect panel brightness.
/sys/class/backlight/intel_backlight exists.
Writing directly to /sys/class/backlight/intel_backlight/brightness changes the 
reported value but the physical panel brightness never changes.

Tried

acpi_backlight=native
removing acpi_backlight=native
rebooting
direct writes to /sys/class/backlight/intel_backlight/brightness

None resolved the issue.

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:  nikhil     3793 F.... pipewire
                      nikhil     3812 F.... wireplumber
 /dev/snd/seq:        nikhil     3793 F.... pipewire
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Wed Aug  5 11:42:33 2026
InstallationDate: Installed on 2026-07-03 (33 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
MachineType: Acer Aspire A715-76G
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-7.0.0-29-generic 
root=UUID=87405b64-95d9-419a-92c0-1ce2a46ab063 ro quiet splash 
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: 07/10/2025
dmi.bios.release: 1.56
dmi.bios.vendor: INSYDE Corp.
dmi.bios.version: V1.56
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: Metis_ADP
dmi.board.vendor: ADL
dmi.board.version: V1.56
dmi.chassis.type: 10
dmi.chassis.vendor: Chassis Manufacturer
dmi.chassis.version: Chassis Version
dmi.ec.firmware.release: 1.4
dmi.modalias: 
dmi:bvnINSYDECorp.:bvrV1.56:bd07/10/2025:br1.56:efr1.4:svnAcer:pnAspireA715-76G:pvrV1.56:rvnADL:rnMetis_ADP:rvrV1.56:cvnChassisManufacturer:ct10:cvrChassisVersion:sku0000000000000000:pfaAspire7:
dmi.product.family: Aspire 7
dmi.product.name: Aspire A715-76G
dmi.product.sku: 0000000000000000
dmi.product.version: V1.56
dmi.sys.vendor: Acer

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug resolute wayland-session

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https://bugs.launchpad.net/bugs/2162884

Title:
  Regression: Intel backlight no longer works on Acer Aspire 7 after
  upgrade from 7.0.0-27 to 7.0.0-29

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