Re: [REQUEST] Add support for Intel DPST (Display Power Saving Technology)

[Jani Nikula <jani.nikula@linux.intel.com>]

On Tue, 16 Apr 2024, José Relvas <josemonsantorelvas@gmail.com> wrote:
> One more question. Some documentation refers to 
> "OPST (OLED power saving technology)". It's my understanding that this
> uses the same hardware blocks and APIs as DPST - only the algorithm
> in software is different. Userspace would need a way to distinguish
> OLED panels from LCD panels so it can use the right algorithm. Is
> there a reliable way of doing this? 
> On my Thinkpad P1 gen 6, the OLED exposes a standard intel_backlight,
> which actually controls the PWM. Afaik, there's no other way of
> telling OLED and LCD apart in userspace.

The intel_backlight interface can actually control the brightness of the
OLED panel using the DPCD interface, not only backlight PWM. It depends
on the panel. See intel_dp_aux_backlight.c. (And yes, backlight can be a
misnomer here, since OLED does not have a backlight.)

I don't actually know the details of OPST, but some OLED panels I've
worked with in the past have CABC, or content adaptive brightness
control, where all of it is handled internally in the panel. You just
tune the aggressiveness or some other mode.

BR,
Jani.



-- 
Jani Nikula, Intel