The DP TX display pipeline (see This Figure) is configured to read video frames from memory via two separate channels: one for video, the other for graphics. The video and graphics layers are alpha-blended to create a single output video stream that is sent to the monitor via the DisplayPort controller. This design does not use the audio feature of the DisplayPort controller, therefore it is not discussed in this user guide. The major components used in this design, as shown in the figure, are:
•DisplayPort DMA (DPDMA)
•Audio/Video (A/V) buffer manager
•DisplayPort controller (DP TX)
•PS-GTR gigabit transceivers
The DPDMA is a 6-channel DMA engine that fetches data from memory and forwards it to the A/V buffer manager. The video layer can consist of up to three channels, depending on the chosen pixel format, whereas the graphics layer is always a single channel. The used pixel formats are described in Video Buffer Format. The remaining two channels are used for audio.
The A/V buffer manager can receive data either from the DPDMA (non-live mode) or from the PL (live mode) or a combination of the two. In this design, only non-live mode is used for both video and graphics. The three video channels feed into a video pixel unpacker and the graphics channel into a graphics pixel unpacker. Because the data is not timed in non-live mode, video timing is locally generated using the internal Video Timing Controller. A stream selector forwards the selected video and graphics streams to the dual-stream video blender.
The video blender unit consists of input color space converters (CSC) and chroma re-samplers (CRS), one pair per stream, a dual-stream alpha blender, and one output color space converter and chroma re-sampler. The two streams must have the same dimensions and color format before entering the blender. The alpha blender can be configured for global alpha (single alpha value for the entire stream) or per pixel alpha. A single output stream is sent to the DisplayPort controller.
The DisplayPort controller supports the DisplayPort v1.2a protocol. It does not support multi-stream transport or other optional features. The DisplayPort controller is responsible for managing the link and physical layer functionality. The controller packs video data into transfer units and sends them over the main link. In addition to the main link, the controller has an auxiliary channel, which is used for source/sink communication.
Four high-speed gigabit transceivers (PS-GTRs) are implemented in the serial input output unit (SIOU) and shared between the following controllers: USB 3.0, DP, SATA, and SGMII Ethernet. The DP controller supports up to two lanes at a maximum line rate of 5.4 Gb/s. The link rate and lane count are configurable based on bandwidth requirements.
For more information on the DisplayPort controller and the PS-GTR interface, see Chapter 29 PS-GTR Transceivers and Chapter 33 DisplayPort Controller in Zynq UltraScale+ Device Technical Reference Manual (UG1085) [Ref 8].