Re: [PATCH v3 0/5] ACPI / processor_idle: Add ACPI v6.0 LPI support

From: Sudeep Holla
Date: Wed Feb 17 2016 - 06:38:01 EST




On 16/02/16 20:08, Rafael J. Wysocki wrote:
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.


No problem, I saw you were quite busy with cpufreq timers past couple of
weeks so didn't bother you.

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.


OK, thanks for the review, will look at them.

--
Regards,
Sudeep