P-tile Avalon® Memory-mapped Intel® FPGA IP for PCI Express* User Guide

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ID 683268
Date 7/14/2021
Public
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4.3.1.6. Avalon® -MM DMA Operations

Avalon® -MM DMA operations are used to transfer large blocks of data. The P-Tile Avalon® -MM IP for PCIe can support DMA operations with an external descriptor controller implemented in the user application.

To interface to the DMA logic included in the P-Tile Avalon® -MM IP for PCIe, the custom DMA descriptor controller must implement the following functions:
  • It must provide the descriptors to the Read Data Mover and Write Data Mover in the P-Tile IP.
  • It must process the status that the DMA Avalon® -MM Read and Write masters provide.

The following figure shows the Avalon® -MM DMA Bridge when a custom external descriptor controller drives the Read and Write Data Movers.

Figure 19.  Avalon® -MM DMA Bridge Block Diagram with Externally Instantiated Descriptor Controller

This configuration includes the PCIe Read DMA and Write DMA Data Movers. The custom DMA descriptor controller must connect to the following Data Mover interfaces:

  • PCIe Read Descriptor Sinks: These are two 174-bit, Avalon® -ST sink interfaces (for normal and priority descriptors). The custom DMA descriptor controller drives read descriptor table entries on this bus. For more details on this interface, refer to Read Data Mover Avalon -ST Descriptor Sinks.
  • PCIe Write Descriptor Sinks: These are two 174-bit, Avalon® -ST sink interfaces (for normal and priority descriptors). The custom DMA descriptor controller drives write descriptor table entries on this bus. For more details on this interface, refer to Write Data Mover Avalon -ST Descriptor Sinks.
  • PCIe Read Data Mover Status Source: The Read Data Mover reports status to the custom DMA descriptor controller on this interface. For more details on this interface, refer to Read Data Mover Status Avalon -ST Source.
  • PCIe Write Data Mover Status Source: The Write Data Mover reports status to the custom DMA descriptor controller on this interface. For more details on this interface, refer to Write Data Mover Status Avalon -ST Source.

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