A4.10 Powering down the processor with system driven L2 flush

When powering down the processor, the PDMINERVA, PDL2, and PDCPU power domains are shut down and all state is lost.

To power down the cluster, apply the following sequence:


  1. Ensure all cores are in shutdown mode, see A4.6 Powering down an individual core.
  2. If the ACP interface is configured, ensure that any master connected to the interface does not send new transactions, then assert AINACTS. This is necessary to prevent ACP transactions from allocating new entries in the L2 cache while the hardware cache flush is occurring.
  3. Assert L2FLUSHREQ HIGH.
  4. Hold L2FLUSHREQ HIGH until L2FLUSHDONE is asserted.
  5. Deassert L2FLUSHREQ.
  6. In an ACE configuration, assert ACINACTM or, in a CHI configuration, assert SINACT. Then, wait until the STANDBYWFIL2 output is asserted to indicate that the L2 memory system is idle. All Cortex®‑A32 processor implementations contain an L2 memory system, including implementations without an L2 cache. This applies to implementations that use the mini-SCU and implementations that use the SCU.
  7. Activate the cluster output clamps.
  8. Remove power from the PDMINERVA and PDL2 power domains.
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