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

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ID 683853
Date 3/28/2022
Public
Document Table of Contents
Document Table of Contents x
1. Design Example Overview 2. Endpoint Design Example 3. Current Limitations of the Design Examples 4. Quick Start Guide 5. P-Tile Avalon Memory-mapped Intel FPGA IP for PCI Express Design Example User Guide Archives A. Document Revision History for the P-Tile Avalon® Memory-mapped Intel FPGA IP for PCI Express Design Example User Guide
2. Endpoint Design Example x
2.1. Block Descriptions 2.2. Programming Model for the Design Example 2.3. Descriptor Format for the Design Example 2.4. DMA Operations Using the Design Example
2.1. Block Descriptions x
2.1.1. DMA Controller 2.1.2. Avalon-MM Address to PCIe Address Mapping 2.1.3. BAR Interpreter
2.1.1. DMA Controller x
2.1.1.1. Register Set 2.1.1.2. Deadlock Risk and Avoidance 2.1.1.3. Interrupts 2.1.1.4. Using the DMA Controller
2.4. DMA Operations Using the Design Example x
2.4.1. Read DMA Example 2.4.2. Write DMA Example
4. Quick Start Guide x
4.1. Design Components 4.2. Directory Structure 4.3. Generating the Design Example 4.4. Simulating the Design Example 4.5. Compiling the Design Example 4.6. Installing the Linux Kernel Driver 4.7. Running the Endpoint Design Example Application
1. Design Example Overview
2. Endpoint Design Example
3. Current Limitations of the Design Examples
4. Quick Start Guide
5. P-Tile Avalon Memory-mapped Intel FPGA IP for PCI Express Design Example User Guide Archives
A. Document Revision History for the P-Tile Avalon® Memory-mapped Intel FPGA IP for PCI Express Design Example User Guide

2.4.2. Write DMA Example

A Write DMA transfers data from the Avalon-MM address space to the PCIe address space (system memory). It uses the Write Data Mover's Avalon® -MM read master to read data from the Avalon® -MM address space and sends it upstream using Memory Write TLPs.

The sequence of steps the example design follows to do a Write DMA is:
  1. Prepare a table of descriptors (padded to 512-bit each) to perform the Write operation and put the table into the system memory.
  2. Using the BAM, send one descriptor from software containing the address of the descriptor table to the DMA Controller, which forwards it to the Read Data Mover.
  3. The Read Data Mover fetches the descriptor table and puts it in a FIFO inside the DMA Controller.
  4. The DMA Controller outputs these descriptors to the Write Data Mover based on the readiness of the Write Data Mover (indicated by an asserted wrdm_desc_ready_o or wrdm_prio_ready_o signal).
  5. The Write Data Mover processes the descriptors by fetching data from the Avalon® -MM memory, and writing it to the appropriate system memory.
  6. The Write Data Mover uses the last descriptor in the descriptor table to indicate the completion of the Write Data Mover’s data processing. This descriptor is an Immediate Write (the data is inside the descriptor itself) to the system memory indicating the Write Data Mover’s operations are done.
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