Re: Regression: Backlight control broken on HP Omen 15‑ax246nf with kernel 7.0.0‑28‑generic

On Wed, Jul 22, 2026 at 7:26 AM Thorsten Leemhuis
<[email protected]> wrote:
>
> On 7/18/26 11:05, harryblanc wrote:
> >
> > I would like to report a regression affecting backlight control on my HP
> > Omen laptop when using kernel 7.0.0‑28‑generic (Ubuntu 24.04 base, Linux
> > Mint 22.3 XFCE).
>
> Hi! Thx for your report. But this is a heavily patched vendor kernel and
> also a series that is EOL. Please test latest vanilla 7.2-rc or and
> report back. Ciao, Thorsten

I was about to ask for that too, so thanks for mentioning it.

> > Summary of the issue:
> > With kernel 7.0, the screen backlight is stuck at maximum brightness.
> > Brightness keys show the OSD and the slider moves, but the actual
> > backlight does not change.
> > With kernel 6.17, brightness works normally.
> >
> > Hardware:
> > - HP Omen 15‑ax246nf
> > - Intel i5‑7300HQ
> > - Intel HD Graphics 630 (i915)
> > - Nvidia GTX 1050 Mobile (disabled via Optimus)
> > - Linux Mint 22.3 XFCE (Ubuntu 24.04 base)
> >
> > Backlight controller:
> > /sys/class/backlight/ → intel_backlight
> > acpi_video0 is no longer present under kernel 7.0.
> >
> > ACPI errors visible only with kernel 7.0:
> > ACPI BIOS Error (bug): Attempt to CreateField of length zero
> > ACPI Error: Aborting method \_SB.WMID.WQBK
> > ACPI BIOS Error (bug): AE_AML_BUFFER_LIMIT
> > ACPI Error: Aborting method \_SB.WMID.HWMC
> > ACPI: video: [Firmware Bug]: ACPI(PEGP) defines _DOD but not _DOS

So it looks like 7.0 uses a different ACPI object as the video bus
representation.

Please send the output of "ls -l /sys/bus/auxiliary/devices/*/" from
the failing kernel.

If you are still able to boot the 6.17-based kernel on the affected
machine, please send the output of "ls -l
/sys/bus/acpi/drivers/video/" obtained while it is running.