Internal Mode - 4.0 English

QDMA Subsystem for PCI Express Product Guide (PG302)

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4.0 English

A queue can be configured to operate in Descriptor Bypass mode or Internal mode by setting the software context bypass field. In internal mode, the queue requires no external user logic to handle descriptors. Descriptors that are fetched by the descriptor engine are delivered directly to the appropriate DMA engine and processed. Internal mode allows credit fetching and status updates to the user logic for run time customization of the descriptor fetch behavior.