Legacy Interrupt - 3.3 English

Versal ACAP CPM DMA and Bridge Mode for PCI Express Product Guide (PG347)

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3.3 English

The QDMA supports the legacy interrupt for physical function, and it is expected that the single queue will be associated with interrupt.

To enable the legacy interrupt, the software needs to set the en_lgcy_intr bit in the register QDMA_GLBL_INTERRUPT_CFG (0x288). When en_lgcy_intr is set, the QDMA will not send out MSI-X interrupt.

When the legacy interrupt wire INTA, INTB, INTC, or INTD is asserted, the QDMA hardware sets the lgcy_intr_pending bit in the QDMA_GLBL_INTERRUPT_CFG (0x288) register. When the software receives the legacy interrupt, it needs to clear the lgcy_intr_pending bit. The hardware will keep the legacy interrupt wire asserted until the software clears the lgcy_intr_pending bit.