APPLIED[M]: [SRU] [L/M] [PATCH 0/1] Fix panel brightness issues on HP laptops

[Andrea Righi]

On Wed, Aug 23, 2023 at 09:03:45AM +0800, Kai-Heng Feng wrote:
> BugLink: https://bugs.launchpad.net/bugs/2032704
> 
> [Impact]
> Brightness can't be changed or can only be changed once on some modern
> HP laptops.
> 
> [Fix]
> BIOS folks identified the issue where the ACPI _PS0 method isn't called
> for the panel device. On Windows the method is being invoked.
> 
> This is due to missing _PSC, but since Windows is the de facto spec, we
> have to perform the same to make the device functional.
> 
> [Test]
> Once the fix is applied, the brightness can be changed smoothly.
> 
> [Where problems could occur]
> According to BIOS folks, Windows also invokes _PS3 for sleep and
> shutdown, we need to tackle that in the future.
> Right now not calling _PS3 has no ill-effect, per BIOS folks.

Applied to mantic/linux-unstable, thanks!

-Andrea