AXI Streaming Intel® FPGA IP for PCI Express* User Guide

ID 790711
Date 2/12/2024
Public

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6.3.5.1.2. Application Logic Guidelines for the AXI Streaming RX Interface in HIP Native Mode

The Application Layer receives data from the AXI Streaming Intel® FPGA IP for PCI Express* over the AXI-ST RX interface. For R-Tile in HIP Native mode, the pX_ss_app_st_rx_ready has to be always high. The buffer control in the application logic needs to be handled by the RX Flow Control Credit interface. Refer to RX Flow Control Interface on page 75 for more details.

The following guidelines must be considered by the Application logic:
  • The pX_ss_app_st_rx_ready signal has to be always high. The buffer control and backpressure need to be handled with the RX Flow Control Credit interface. Refer to RX Flow Control Credit Interface for more details.
  • The header may occur in any of the segments (S0/1/2/3).
  • For a single TLP spanning across multiple segments, the application logic needs to process the TLP in the order of the segment indices (segment S0 → S1 → S2 → S3 → S0).
  • For multiple TLPs arriving on the same clock cycle, the application logic needs to process the TLPs in the order of the segment indices (segment S0 → S1 → S2 → S3 → S0).
  • The IP does not use segment 2 and segment 3 if segment 0 AND segment 1 are unused.
    Note that this behavior only applies in Production devices or Engineering Samples with the following OPNs:
    • AGIx027R29AxxxxR2
    • AGIx027R29AxxxxR3
    • AGIx027R29BxxxxR3
    • AGIx023R18AxxxxR0
    • AGIx041R29DxxxxR0
    • AGIx041R29DxxxxR1
    • AGMx039R47AxxR0

    For more details on OPN decoding, refer to the Available Options section of the Intel Agilex® 7 FPGAs and SoCs Device Overview.

  • - There is a maximum of three headers in a single clock cycle. The following table describes the possible combinations across segments:
    Table 36.  RX AXI-ST with 1024-Bit Tdata Bus (x16 HIP Native Mode - 1024 Bits, 4 Segments x 256 Bits Wide)
    S0 S1 S2 S3
    H, D H, D H, D -
    H, D H, D H, D D
    - H, D - H, D
    - H, D D H, D
      H, D D H
    H, D D H, D H, D
    H, D D H, D H

Example of HIP-Native mode packing scheme in Gen5x16 with a 1024-bit 4-segment bus on the RX AXI-ST Interface:

1st Command with Data - Payload 16 Bytes

2nd Command with Data - Payload 32 Bytes

3rd Command with Data - Payload 64 Bytes

4th Command with Data - Payload 60 Bytes

5th Command without Data

6th Command with Data – Payload 56 Bytes

7th Command with Data – Payload 20 Bytes

8th Command without Data