linux-kernel - Re: [PATCH v8 0/6] ACPI / processor

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Date:	Fri, 8 Jul 2016 15:43:07 +0100
From:	Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	"Rafael J. Wysocki" <rafael@...nel.org>,
	ACPI List <linux-acpi@...r.kernel.org>,
	"Rafael J . Wysocki" <rjw@...ysocki.net>,
	Vikas Sajjan <vikas.cha.sajjan@....com>,
	Sunil <sunil.vl@....com>,
	PrashanthPrakash <pprakash@...eaurora.org>,
	Al Stone <al.stone@...aro.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	LKML <linux-kernel@...r.kernel.org>,
	ALKML <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v8 0/6] ACPI / processor_idle: Add ACPI v6.0 LPI support

On Fri, Jul 08, 2016 at 12:04:40PM +0100, Sudeep Holla wrote:
> 
> 
> On 07/07/16 22:02, Rafael J. Wysocki wrote:
> >On Thu, Jul 7, 2016 at 7:10 PM, Sudeep Holla <sudeep.holla@....com> wrote:
> >>ACPI 6.0 introduced LPI(Low Power Idle) states that provides an alternate
> >>method to describe processor idle states. It extends the specification
> >>to allow the expression of idle states like C-states selectable by the
> >>OSPM when a processor goes idle, but may affect more than one processor,
> >>and may affect other system components.
> >>
> >>LPI extensions leverages the processor container device(again introduced
> >>in ACPI 6.0) allowing to express which parts of the system are affected
> >>by a given LPI state. It defines the local power states for each node
> >>in a hierarchical processor topology. The OSPM can use _LPI object to
> >>select a local power state for each level of processor hierarchy in the
> >>system. They used to produce a composite power state request that is
> >>presented to the platform by the OSPM.
> >>
> >>Since multiple processors affect the idle state for any non-leaf hierarchy
> >>node, coordination of idle state requests between the processors is
> >>required. ACPI supports two different coordination schemes: Platform
> >>coordinated and  OS initiated.
> >>
> >>This series aims at providing basic and initial support for platform
> >>coordinated LPI states.
> >>
> >>v7[7]->v8:
> >>         - Replaced HAVE_GENERIC_CPUIDLE_ENTER with CPU_IDLE_ENTER_WRAPPED
> >>           macro, which is more cleaner and definately less confusing :)
> >>           (Thanks to Rafael for the suggestion)
> >
> >Patches [3-6/6] definitely look a lot cleaner to me now. :-)
> >
> >That said, the name of the macro I suggested was just an example, so
> >if people don't like this one, it'd be fine to change it as far as I'm
> >concerned.
> >
> 
> I can think of addition to indicate it's pm notifiers wrapper.
> i.e. CPU_IDLE_ENTER_PM_NOTIFIERS_WRAPPED. Is it too long ? I am happy
> with the way it is too.

CPU_PM_CPU_IDLE_ENTER() ? Anyway, that's really not a problem IMO,
it makes sense to at least mention CPU PM in it given that's what
the CPUIDLE enter function is wrapped within.

Lorenzo