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    SubjectRe: [PATCH v2 0/5] CPU PM notifiers
    On Friday 09 September 2011 11:30 PM, Kevin Hilman wrote:
    > Santosh Shilimkar<> 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<>
    Will add.
    Thanks for the review Kevin.



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