The Pass-Through application (KCU105) checks if a monitor is connected soon after it executes. If a monitor is already connected, it starts up the following options as shown in the following figure from which to choose (KCU105).
Selecting either r or s puts the system in Pass-Through mode, where the video received by the RX is
forwarded to the TX. It configures the vid_phy_controller and
sets up the DisplayPort for RX. If a DisplayPort source (for example, GPU) is already
connected to DisplayPort RX Subsystem, it starts the training. Otherwise, the training starts
when the cable is plugged in. As soon as the training is completed, the application starts the
DisplayPort TX Subsystem. The video should be seen on the monitor after the TX is up. The
previous figure shows the UART transcript. The transcript might differ based on the training
done by the GPU.