This step initializes a driver instance for the given DMA engine and resets the engine.Įnable interrupts if chosen to use interrupt mode. To use the Simple mode DMA engine for transfers, the following setup is required:ĭMA Initialization using XAxiDma_CfgInitialize() function. XAxiDma_Pause() or XAxiDma_Reset() - Software Initialization _ XAxiDma_StartBdRingHw(), or XAxiDma_BdRingStart(), _ The following diagram shows the state transition for the DMA engine: | XAxiDma_BdRingFree() XAxiDma_BdRingFromHw() | The application use XAxiDma_BdRingFree() to put them into the Free group.īDs are expected to transition in the following way for continuous DMA transfers: XAxiDma_BdRingAlloc() XAxiDma_BdRingToHw()įree -> Pre-process -> Hardware The application can check the transfer status of these BDs. Post-process: The BDs that have been processed by hardware and have been extracted from the Hardware group with XAxiDma_BdRingFromHw(). Doing so can cause data corruption and lead to system instability. It is considered an error for the application to change BDs while they are in this group. These BDs are under hardware control and may be in a state of awaiting hardware processing, in process, or processed by hardware. Hardware: The BDs that have been enqueued to hardware with XAxiDma_BdRingToHw(). The application modifies these BDs through driver API to prepare them for DMA transactions. Pre-process: The BDs that have been allocated with XAxiDma_BdRingAlloc().

Each group consists of 0 or more adjacent BDs:įree: The BDs that can be allocated by the application with XAxiDma_BdRingAlloc(). Within the ring, the driver maintains four groups of BDs.

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