2.9.6 Power Dependency Control Matrix

The SSE-200 subsystem defines a control matrix that allows the power mode (ON state) of one domain to affect another power domain.

The following table shows how this matrix is structured.

Table 2-13 PDCM structure

Domain PD_SYS PD_SRAM0 PD_SRAM1 PD_SRAM2 PD_SRAM3
PD_SYS PPUHWSTATE_ON Conf Conf Conf Conf Conf
PD_CPU0CORE PPUHWSTATE_ON Yes Conf Conf Conf Conf
PD_CPU1CORE PPUHWSTATE_ON Yes Conf Conf Conf Conf
PD_SRAM0 PPUHWSTATE_ON Yes Conf - - -
PD_SRAM1 PPUHWSTATE_ON Yes - Conf - -
PD_SRAM2 PPUHWSTATE_ON Yes - - Conf -
PD_SRAM3 PPUHWSTATE_ON Yes - - - Conf
PD_CRYPTO PPUHWSTATE_ON Yes - - - -
PDEXP0 Conf Conf Conf Conf Conf
PDEXP1 Conf Conf Conf Conf Conf
PDEXP2 Conf Conf Conf Conf Conf
PDEXP3 Conf Conf Conf Conf Conf

The left column of the table lists the power dependency inputs while the heading row lists the power domains that are being controlled. The power dependency inputs are either:

  • The ON state of each power domain in the system
  • Expansion power control dependency signals, PDEXP0 to PDEXP3, that are driven by expansion logic outside the subsystem indicating the ON state of external power domains.

If a power domain is sensitive to a dependency input, after the controlled power domain is ON, the power domain remains ON while any of the dependency inputs is HIGH. Therefore the PDCM is used primarily to define when a power domain must not enter a lower power state. It is not designed to support powering up of any power domain.

The power control matrix interactions have the following features:

  • For the PD_SYS power domain:

    • It can be requested to turn ON either by any GPR, by any EWC or by its associated Power Q-Channel Interface. PD_SYS remains ON when any of the other power domains in the system not related to debug, are ON.

    • PD_SYS can be configured to remain ON when any of the Expansion Power Dependency inputs are ON.
    • If PD_SYS is configured to be sensitive to itself, then when it is ON, it stays ON.
  • Each processor power domain can be requested to turn ON either by its associated GPR or EWC.
  • PD_DEBUG can be requested to turn on by the debug DAP or by its associated power Q-Channel interface.
  • For any PD_SRAM<n>:

    • Each can be woken by sending access to the SRAM.

    • Each can be configured to remain ON depending on the CPU power state, the PS_SYS power state, or if any of the Expansion Power Dependency inputs are ON.
    • If each is configured to be sensitive to itself, then when it is ON, it stays ON.

The PDCM and sensitivity inputs for each power domain allows for the power control of the system to be primarily performed using only dynamic power transitions. This reduces the number of software interactions that are required for system management and therefore improves its responsiveness and contributes to further power reduction.

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