Resets - 1.0 English

Versal ACAP DMA and Bridge Subsystem for PCI Express Product Guide (PG344)

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1.0 English

The QDMA supports all the PCIe defined resets, such as link down, reset, hot reset, and function level reset (FLR) (supports only Quiesce mode).

Soft Reset

Reset the QDMA logic through the soft_reset_n port. This port needs to be held in reset for a minimum of 100 clock cycles (axi_aclk cycles).

This does not reset PCIe hard block. It resets only the DMA portion of logic. This reset can be asserted if there is a DMA hang or some error condition.

Soft Reset Use Cases

The uses cases that prompt the use of soft_reset include:
  • DMA hangs and user is not getting proper values.
  • DMA transfer have errors, but the PCIe links are good.
  • DMA records some asynchronous error
After soft_reset, you must reinitialize the queues and program all queue context.