As part of the HDMI 2.1 TX Subsystem, the AMD LogiCORE™ IP High-bandwidth Digital Content Protection (HDCP™) transmitters are designed to transmit audiovisual content securely between two devices that are HDCP capable. In this HDMI 2.1 TX Subsystem, both HDCP 1.4 and HDCP 2.3 transmitter IP cores are included, and can be enabled by the HDCP option in the Vivado IDE.
As a guideline, in FRL mode, all contents are protected with HDCP 2.3. On the other hand, in TMDS mode, HDCP 2.3 is used to encrypt content at Ultra-High Definition (UHD) while HDCP 1.4 is the legacy content protection scheme used at lower resolutions to be backward compatible with HDCP 1.4 only sinks.
The following figure shows a configuration of the HDMI TX where both HDCP 1.4 and 2.3 are enabled. With both HDCP protocols enabled, the HDMI Subsystem configures itself in the cascade topology where the HDCP 1.4 and HDCP 2.3 are connected back-to-back. The HDCP Egress interface of the HDMI transmitter sends unencrypted audiovisual data, which is encrypted by the active HDCP block and sent back into the HDMI transmitter over the HDCP Ingress interface for transmission over the link. The HDMI TX Subsystem ensures that only one of the HDCP protocols is active at any given time and the other is passive by calling the relevant HDMI 2.1 TX Subsystem API functions.