Subject: Re: [PATCH] cpuidle: Default y for pseries

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 11 Jan 2012 18:05:35 +1100

On Tue, 2012-01-10 at 22:08 -0800, Linus Torvalds wrote:
> On Tue, Jan 10, 2012 at 5:05 PM, Benjamin Herrenschmidt
> <[email-masked]> wrote:
> >
> > Linus, do you want to just pick that up or should I put it into powerpc.git
> > and ask you to pull ? I will have 2 or 3 other fixes there later today,
> > but I wanted to make sure you were ok with the approach with this
> > specific one.
> 
> It doesn't seem to be all that different from the "default y if ACPI"
> case, so I guess it works ok.

It works for my case, that's tested, but ...

> That said, I wonder if the right approach wouldn't be
> 
>    default y if SUPPORT_CPU_IDLE
> 
> or something along those lines. And then both ACPI and PPC_PSERIES
> could just select that instead. Because I do hate having random
> board-level knowledge in something like this. I dunno.

I tend to agree, I wasn't too keen on touching ACPI related stuff I
suppose it shouldn't be hard :-) Btw, what about the change:

-	default ACPI
+	default y if ACPI

(To be honest I'm not sure what the first form does in details).

Oh, also, I just see that in drivers/acpi/Kconfig:

config ACPI_PROCESSOR
	tristate "Processor"
	select THERMAL
	select CPU_IDLE
	default y

Hrm... maybe I should just do the same in pseries and remove both the
"default" statements above, what do you think ?

On pSeries I'm keen to build that in rather than make it a module too
because you get no idle handling until it loads which can be
problematic. Built-in, it seems to be quite early in the link order (if
we can still trust that nowadays ...).

Cheers,
Ben.