On Tuesday, April 19, 2016 01:30:10 PM Sudeep Holla wrote:

ACPI 6.0 introduced an optional object _LPI that provides an alternate
method to describe Low Power Idle states. 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 patch adds initial support for Platform coordination scheme of LPI.

Cc: "Rafael J. Wysocki" <redacted>
Signed-off-by: Sudeep Holla <redacted>
---
 drivers/acpi/bus.c              |  11 +-
 drivers/acpi/processor_driver.c |   2 +-
 drivers/acpi/processor_idle.c   | 441 +++++++++++++++++++++++++++++++++++-----
 include/acpi/processor.h        |  25 ++-
 include/linux/acpi.h            |   4 +
 5 files changed, 422 insertions(+), 61 deletions(-)

Hi Rafael,

Yet to be discussed(retained as in from previous version):

I somehow didn't realize that you had been waiting for my feedback.  Sorry
about that.

- Kconfig entry removal: Need feedback on how to deal with that
  without having to introduce dummy _CST related ARM64 callbacks
- Didn't defer processing of LPI buffers to flattening as it
  results in the same buffer decoded multiple times
- ACPI_CSTATE_INTEGER : IMO it's reasonable to keep it aroundsince the
  it's part of LPI specification(not just ARM FFH)

OK, I'll have a look tomorrow.

Thanks,
Rafael