linux-kernel - Re: [PATCH v3 0/5] ACPI / processor

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Date:	Tue, 16 Feb 2016 21:08:26 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Sudeep Holla <sudeep.holla@....com>
Cc:	linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-ia64@...r.kernel.org, x86@...nel.org,
	Al Stone <al.stone@...aro.org>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>,
	Mahesh Sivasubramanian <msivasub@...eaurora.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	Prashanth Prakash <pprakash@...eaurora.org>
Subject: Re: [PATCH v3 0/5] ACPI / processor_idle: Add ACPI v6.0 LPI support

On Wednesday, December 02, 2015 02:10:41 PM Sudeep Holla 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.
> 
> v2[2]->v3:
> 	- rebased against v4.4-rc3
> 	- fixed couple of issues reported by Prashanth and review comments
> 	  from Ashwin
> 
> v1[1]->v2[2]:
> 	- Fixed support for ACPI0010 processor container
> 	- moved sleep state code out of processor_idle
> 
> Note the ARM64 specific changes are not part of this series as it's still
> WIP and there are other consolidation happening in there. For reference
> and testing, I have pushed a branch[3]

Sorry for the slow response here.

It doesn't look too bad overall, but there are some things in it I'd like to
be done differenty.  Please see comments on the individual patches.

Thanks,
Rafael