SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
At any given time, the PDMA can be in one of three different states, as shown in Table 11-81.
Operational State | Description |
---|---|
Init | This is the initial state of the machine during and immediately after reset. During this state, all of the RAMs inside the PDMA will be initialized to known values including the ECC redundant parity bits. While in the init state, the DMA will de-assert all ready signals on all applicable target interfaces and will de-assert all request signals on all applicable controller interfaces. The PDMA will automatically transition out of the init state into the idle state when all of the RAM initialization has been completed. |
Idle | Once the PDMA leaves the Init state, it enters the Idle state whenever no outstanding transactions are pending on any of the PDMA interfaces (controller or target). The Idle state is generally a transient state and is used by the PDMA to determine when it is appropriate to allow the SoC power management complex to turn off the clock. For clock stop purposes, the module will only report idle if all DMA channels are disabled using the enable bit in PSIL register 2 for each channel. |
Active | The PDMA enters the active state as soon as it issues a transaction or receives a transaction on any interface that uses a split protocol (expects a later response for a request). When all transactions have been accounted for (responses have all been either received or sent) the PDMA transitions to the Idle state. |