Public bug reported:
Regression in Ubuntu 24.04.4 HWE kernel: on an Acer Nitro AN515-57
(Intel Tiger Lake UHD Graphics + NVIDIA RTX 3050 Ti), internal display
brightness control works correctly with Linux 6.17.0-40-generic but no
longer works with Linux 7.0.0-28-generic. The brightness keys, GNOME
brightness slider, and `brightnessctl` all update
`/sys/class/backlight/intel_backlight/brightness` and
`actual_brightness` successfully, but the physical panel brightness
never changes. The display is driven by the Intel i915 driver
(`intel_backlight` is the active backlight device, OpenGL renderer is
Intel UHD Graphics). The issue persists without any custom kernel
parameters (e.g. after removing `i915.enable_dpcd_backlight=1`) and
disappears immediately when booting the same Ubuntu installation with
the 6.17.0-40 kernel, indicating a kernel regression introduced between
6.17.0-40 and 7.0.0-28.
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
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Sun Jul 26 17:14:21 2026
InstallationDate: Installed on 2025-09-03 (326 days ago)
InstallationMedia: Ubuntu 24.04.3 LTS "Noble Numbat" - Release amd64
(20250805.1)
MachineType: Acer Nitro AN515-57
ProcFB:
0 i915drmfb
1 nvidia-drmdrmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-28-generic
root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash 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: 01/06/2022
dmi.bios.release: 1.15
dmi.bios.vendor: Insyde Corp.
dmi.bios.version: V1.15
dmi.board.asset.tag: Type2 - Board Asset Tag
dmi.board.name: Scala_TLS
dmi.board.vendor: TGL
dmi.board.version: V1.15
dmi.chassis.type: 10
dmi.chassis.vendor: Acer
dmi.chassis.version: V1.15
dmi.ec.firmware.release: 1.9
dmi.modalias:
dmi:bvnInsydeCorp.:bvrV1.15:bd01/06/2022:br1.15:efr1.9:svnAcer:pnNitroAN515-57:pvrV1.15:rvnTGL:rnScala_TLS:rvrV1.15:cvnAcer:ct10:cvrV1.15:sku0000000000000000:pfaNitro5:
dmi.product.family: Nitro 5
dmi.product.name: Nitro AN515-57
dmi.product.sku: 0000000000000000
dmi.product.version: V1.15
dmi.sys.vendor: Acer
** Affects: linux-hwe-7.0 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble
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Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2161841
Title:
Regression: Internal display brightness no longer works on Acer Nitro
AN515-57 with Linux 7.0.0-28-generic (Ubuntu 24.04.4 HWE). Brightness
works correctly with Linux 6.17.0-40-generic.
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