Re: [PATCH v2 0/5] CPU PM notifiers

[Santosh]

On Friday 09 September 2011 11:30 PM, Kevin Hilman wrote:
> Santosh Shilimkar<santosh.shilimkar@xxxxxx>  writes:
>
> [...]
>
> > This patch set tries to address 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 cluster 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 cluster 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.
>
> Stepping back from my earlier objections, I think I had a fundamental
> misunderstanding about what these notifiers should be used for.
>
> The current assumptions/goals seem to be
>
> 1) used only for devices in the same power domain as the CPU (cluster)
> 2) use only for one specific power state of the CPU (cluster): off.
>
> For awhile now, we've been discussing how to better coordinate CPU PM
> transitions (CPUidle) with non-CPU PM transitions (runtime PM) for
> devices that are tightly coupled to the CPU, but not necessarily in the
> same powerdomain.
>
> I was assuming (and hoping) that CPU PM notifiers could be used to do
> that, but the more I think about it, I don't think we can achieve the
> current CPU PM goals and the coordination with runtime PM with this
> series.
>
> I think it's more likely that we'll need to do some work with Rafael's
> new PM domains to make that work correctly.
>
> So, I'll retract my objections to this series, and feel free to add
>
> Reviewed-by: Kevin Hilman<khilman@xxxxxx>
Will add.
Thanks for the review Kevin.

Regards
Santosh

Regards

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