Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 7/19/2024
Public

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5.6.5.4. Bus Management Unit

The BMU manages data and descriptor DMA fetches. It prioritizes DMA fetches from different queues before issuing DMA requests to the BUS-GM. The BMU has one RxFIFO to receive data, one for USB 2.0 in Host mode, and one for each USB 3.1 concurrent port. Each RxFIFO has a corresponding RxQueue to which the list processor queues in RxData and RxDescriptor write back commands.

The TxFIFOs provide prefetch buffers for the IN endpoints in device mode and OUT transfers in Host mode. Because devices cannot predict the endpoint from which the host requests data, each active endpoint in device mode has a TxFIFO. For Host mode to support concurrent USB 2.0 and USB 3.1 transfers, one dedicated TxFIFO is allocated for the USB 2.0 OUT transfers. Because concurrent transfers are supported on each USB 3.1 port, one TxFIFO is provided to each USB 3.1 port. Each TxFIFO has a corresponding TxQueue to which the list processor issues Tx fetch requests.