RE: [RFC] ACPI: platform-profile: support for AC vs DC modes

["Limonciello, Mario" <Mario.Limonciello@amd.com>]

[AMD Official Use Only]

> > I don't think that's right for the PSC Thinkpads.  They have dedicated
> > different tunings for each of the slider positions on AC vs DC.
> >
> > So "balanced" on AC will not be the same as "balanced" on DC.
> 
> I see, but it is not like balanced on AC is closer to performance
> on DC then it is to balanced on DC, right? IOW in the UI we should
> still call them both balanced ?

I feel that's a gross oversimplification to say balanced on AC is close
to performance on DC.  There are *so many* other (otherwise invisible)
tuning knobs behind what PSC does that Lenovo has weighed out the benefits
of using for different circumstances.  

You nerf all this by just having one user space facing knob and let userspace
change to performance mode when you on charger.

At least the way Windows does this is that it offers "one" UI slider but you
have last selected values based on if you're plugged in or on battery.

1) So on battery I might have balanced selected to start out.
2) Then I plug in a charger, and balanced is still selected but this has
different characteristics from balanced on battery.
3) Now I change to performance while on charger.
4) Then I unplug charger and it goes back to my selection for battery: "balanced".

> 
> If that is right then I think my point still stands, if PSC
> has 2 separate slots (one AC one DC) for the performance
> setting, then we can just set both when userspace selects a
> performance level and have the actual e.g. balanced -> performance
> change be done by userspace when userspace select the machine
> has been connected to a charger.

But you *don't want to* actually select performance when you switch to a
charger.  If you have 3 value slots for AC and 3 value slots for DC you
should only be swapping between what is in those 3 values slots.

> 
> Regards,
> 
> Hans
> 
>