C2H Timer - 3.3 English

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

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3.3 English

The C2H timer is a trigger mode in the Completion context. It supports 2048 queues, and each queue has its own timer. When the timer expires, a timer expire signal is sent to the Completion module. If multiple timers expire at the same time, then they are sent out in a round robin manner.

Reference Timer

The reference timer is based on the timer tick. The register QDMA_C2H_INT (0xB0C) defines the value for a timer tick. The 16 registers QDMA_C2H_TIMER_CNT (0xA00-0xA3C) has the timer counts based on the timer tick. The timer_idx in the Completion context is the index to the 16 QDMA_C2H_TIMER_CNT registers. Each queue can choose its own timer_idx.