Intel® FPGA Streaming Video Protocol Specification

ID 683397
Date 5/15/2024
Document Table of Contents

4.4.4. Optional Backpressure

Most of the connectivity video IPs such as SDI, HDMI and DisplayPort do not support backpressure and you can omit or drive high TREADY.

These modules cannot support backpressure because this type of connectivity IP works on a live video stream and uses a synchronous pixel clock rate to drive the video interface. Hence, any TREADY backpressure breaks the video timing relationship.

However, other connectivity IPs have a data packet exchange based on command driven protocols, such as PCIe and Ethernet. Backpressure requires TREADY to process the AXI4-S flow control mechanism and the full-raster compatible interfaces to support an optional TREADY signal. To analyze the effect TREADY has on the backpressure that a transmitter full-raster interface can experience during data transfer, look at the relationship of pixel clock rate between the video interfaces that exchange video data. The two scenarios are:

  • Synchronous pixel clock rates
  • Asynchronous pixel clock rates