Questions on adding backlight support for the i915 driver

[Adrian Chadd]

On 30 January 2015 at 20:19, Elizabeth Myers <elizabeth at interlinked.me> wrote:
> On 01/30/15 17:25, Justin Hibbits wrote:
>> Would it make sense to have a generic 'backlight' driver framework
>> that we plug into?  I wrote a backlight driver (well, 2, but both show
>> up as dev.backlight in sysctl) for powerpc, but if we want to have
>> even more individual backlight drivers, I think it makes sense to make
>> them all look the same, with similar configuration properties.
>>
>> - Justin
>
> I was thinking the same thing myself. There's a lot of different
> backlights out there, and acpi_video(4) obviously can't cover them all,
> which seems to define the de facto "standard" MIB for brightness sysctls
> (which upower presently uses).
>
> I hate to bikeshed, but I would humbly suggest adding an MIB hierarchy
> such as hw.backlight.<hw_type>.<backlight_no>.brightness (and maybe
> brightness_raw for advanced users who want/need more control).

Woo! A patch!

I'm happy with this, but you'll want to cc: kib at least who looks
after the i915 code. Hi kib!

I think this is fine for the short term and lets us experiment without
committing to a fully public API for this for the short term.

Do you have brightness buttons anywhere? What happens when you set it
through this API and then you use the backlight buttons?



-adrian