[PATCH 0/3] CPU PM notifiers

Rafael J. Wysocki rjw at sisk.pl
Mon Jun 13 14:37:48 EDT 2011

On Monday, June 13, 2011, Colin Cross wrote:
> This patch set tries to address Russell's concerns with platform
> pm code calling into the driver for every block in the Cortex A9s
> during idle, hotplug, and suspend.  The first patch adds cpu pm
> notifiers that can be called by platform code, the second uses
> the notifier to save and restore the GIC state, and the third
> saves the VFP state.
> The notifiers are used for two types of events, CPU PM events and
> CPU complex PM events.  CPU PM events are used to save and restore
> per-cpu context when a single CPU is preparing to enter or has
> just exited a low power state.  For example, the VFP saves the
> last thread context, and the GIC saves banked CPU registers.
> CPU complex events are used after all the CPUs in a power domain
> have been prepared for the low power state.  The GIC uses these
> events to save global register state.
> Platforms that call the cpu_pm APIs must select
> L2 cache is not covered by this patch set, as the determination
> of when the L2 is reset and when it is retained is
> platform-specific, and most of the APIs necessary are already
> present.
>  arch/arm/Kconfig              |    7 ++
>  arch/arm/common/gic.c         |  212 +++++++++++++++++++++++++++++++++++++++++
>  arch/arm/include/asm/cpu_pm.h |   54 +++++++++++
>  arch/arm/kernel/Makefile      |    1 +
>  arch/arm/kernel/cpu_pm.c      |  181 +++++++++++++++++++++++++++++++++++

Is there any reason why this has to be ARM-specific?  There are other
architectures where this kind of feature might make sense (SH and
powerpc at least).

Besides, is there any overlap between this feature and the CPU hotplug


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