A4.5
Power control
All power mode transitions are performed at the request of the power controller, using a P-Channel
interface to communicate with the Cortex-A76 core.
There is one P-Channel per core, plus one P-Channel for the cluster. The Cortex-A76 core provides the
current requirements on the
PACTIVE
signals, so that the power controller can make decisions and
request any change with
PREQ
and
PSTATE
. The Cortex-A76 core then performs any actions necessary
to reach the requested power mode, such as gating clocks, flushing caches, or disabling coherency, before
accepting the request.
If the request is not valid, either because of an incorrect transition or because the status has changed so
that state is no longer appropriate, then the request is denied. The power mode of each core can be
independent of other cores in the cluster, however the cluster power mode is linked to the mode of the
cores.
A4 Power management
A4.5 Power control
100798_0300_00_en
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A4-52
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Summary of Contents for Cortex-A76 Core
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