Fast port switching in an audiovisual receiver by use of port pre-authentication by a partial PHY decoder core

A method of performing HDCP authentication in an HDMI sink that has a plurality of HDMI ports, at least one of which is an inactive port, the method comprising:

• using a full HDMI physical layer decoder core to decode a first set of HDMI signals received on an active port of the plurality of HDMI ports;
• sequentially checking each inactive port of the plurality of HDMI ports to determine whether each said inactive port has an external device connected thereto;
• and
• for only those inactive port or ports determined to have an external device connected thereto, performing HDCP authentication on said inactive port by using a partial HDMI physical layer decoder core to decode a second set of HDMI signals for use in HDCP authentication, including for each of the inactive ports,
• using a first decoder in the partial HDMI decoder core to decode a vertical synchronization signal in the second set of HDMI signals;
• and
• using only a second decoder in the partial HDMI decoder core to decode an encryption enable signal in the second set of HDMI signals, wherein the first decoder and the second decoder are the only operational decoders in the partial HDMI decoder core during HDCP authentication of inactive ports.

An HDMI sink comprising:

• a plurality of HDMI ports;
• a first physical layer decoder core to decode TMDS data channels of a first HDMI link associated with an active port of the plurality of HDMI ports to extract media data from the TMDS data channels, the first physical layer decoder core including at least three TMDS channel decoders;
• a second physical layer decoder core to decode TMDS data channels of a second HDMI link associated with an inactive port of the plurality of HDMI ports for use in performing HDCP authentication of the inactive port, the second physical layer decoder core including no more than two TMDS channel decoders;
• a multiplexer coupled between the plurality of HDMI ports and the second physical layer decoder core;
• authentication circuitry to perform HDCP authentication on each port of the plurality of HDMI ports;
• and
• a plurality of discrete time oscillators coupled to the second physical layer decoder core through a multiplexer, each discrete time oscillator coupled to input a synchronization signal in one of the TMDS data channels associated with an inactive port and to output a copy of the synchronization signal, wherein the copy of the synchronization signal from each discrete time oscillator is provided to the authentication circuitry for use in performing HDCP authentication on inactive ports.