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    SubjectRe: [PATCH RFC] arm: l2x0: Leverage power saving features
    Hello Soren,

    On Fri, Mar 01, 2013 at 06:51:26PM +0000, Soren Brinkmann wrote:
    > Enable the 'dynamic clock stop' and 'standby mode' features in the
    > l2x0 disable path.
    >
    > Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
    > ---
    > Hi,
    >
    > we are currently implementing a suspend to RAM like low power mode for
    > Zynq.
    > The code for entering suspend looks like this:
    > outer_disable();
    > cpu_suspend(0, zynq_pm_suspend);
    > outer_resume();
    >
    > In our low power guidelines we mention the pl310's standby and clock stop
    > feature and that they should be enabled for low power modes. The question
    > arising here now is: Does the outer_disable() make these features redundant,
    > or does it make sense to add it like shown in this patch?

    The settings in the power control register are unrelated to CPU suspend
    afaict. Instead, they are for semi-autonomous entry to non-destructive
    low-power states (e.g. when the L2 is idle for n cycles, or all of the L1
    masters have asserted WFI).

    This raises the question of whether or not we should poke this register at
    all (other than saving/restoring it across suspend, which *is* destructive).
    I personally think that this stuff is better off being dealt with in
    firmware and initialised there, which follows what we do for other registers
    like this.

    Will


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