The purpose of this page is document how to enable basic CPU Idle on Renesas platforms (RCar-H2 being the primary target). CPUIdle is a standard Linux power management framework aimed at reducing CPU power consumption when it is idle.
Note: Disabling arch timer here will probably have an impact on all the other SH platforms supported in multiplatform config. A "smarter" approach, i.e dynamic, will have to be used if the arch timer cannot be fixed.
The patches to enable CPUIdle for the CA7 cluster are available here.
All these changes are available in this http://git.baylibre.com/pub/bcousson/linux-sh/log/?h=cpuidle.
Note: The target_residency and exit_latency will have to be refined based on power measurement and performance impact on differents key use cases.
Power measurement with and without CPUIlde enabled:
TBD. Doing accurate measurement will require modifying the Lager board as explained here : Enabling Power Measurements on Renesas H2 Lager Board
First results will be posted as soon as the board is modified.