Hi Ulf,

On Wed, Mar 14, 2018 at 05:58:10PM +0100, Ulf Hansson wrote:

For ARM, the PSCI firmware interface may be managing the power to the CPUs.
Depending on the SoC, CPUs may also be arranged in hierarchical manner, which
could add another level of complexity from a CPU idle management point of view.

PSCI v1.0+ adds support for the so called OS initiated CPU suspend mode, which
enables a more fine grained method, allowing Linux to get more control, in
regards to being energy efficient. This is typically useful for these kind of
complex battery driven platforms.

The series is based on v4.16-rc5, but applies also as of today to Rafael's
linux-pm.git next branch. The code has been tested on a QCOM 410c dragonboard
and I except that test coverage should be increased by some more boards
shortly (for ARM64 with PSCI OSI support - only a few DT changes are needed).

Do we have any numbers to show how this affects energy efficiency?

Are there any other platforms with OSI support?

Thanks,
Mark.