Requester Completion Interface Operation - 1.0 English

Versal Adaptive SoC Integrated Block for PCI Express LogiCORE IP Product Guide (PG343)

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Completions for requests generated by the user logic are presented on the integrated block Request Completion (RC) interface. See the following figure for an illustration of signals associated with the requester completion interface. When straddle is not enabled, the integrated block delivers each TLP on this interface as an AXI4-Stream packet. The packet starts with a 96-bit descriptor, followed by data in the case of Completions with a payload.

Figure 1. Requester Completion Interface

The RC interface supports two distinct data alignment modes for transferring payloads. In the Dword-aligned mode, the integrated block transfers the first Dword of the Completion payload immediately after the last Dword of the descriptor. In the address-aligned mode, the integrated block starts the payload transfer in the beat following the last Dword of the descriptor, and its first Dword can be in any of the possible Dword positions on the datapath. The alignment of the first Dword of the payload is determined by an address offset provided by the user application when it sent the request to the integrated block (that is, the setting of the addr_offset[2:0] input of the RQ interface). Thus, the address-aligned mode can be used on the RC interface only if the RQ interface is also configured to use the address-aligned mode.