Partial HDMI PHY Decoder for Instant Port Switching
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Solution Overview
Problem
HDMI sink devices experience noticeable delays during HDCP authorization when switching between ports, causing user inconvenience due to the need for repeated authentication routines.
Innovation Solution
Implementing a partial HDMI physical layer decoder core for pre-authentication of inactive ports, which reduces the need for full authentication upon port switching by maintaining authentication with minimal circuitry and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full HDCP authentication is performed on all HDMI ports during port switching, then security and authorization are ensured, but user experience deteriorates due to noticeable delays and blank screens
Solution Approach 1:
The system performs preliminary HDCP authentication on inactive HDMI ports before they are activated. The partial PHY decoder core continuously monitors and pre-authenticates inactive ports, so when a port switch occurs, the authentication is already complete or near-complete, eliminating the visible delay and blank screen that users experience during port switching.
2Speed
If pre-authentication is performed on all inactive HDMI ports, then port switching speed is improved, but chip area and power consumption increase
Solution Approach 1:
The authentication system is segmented into two parts: a full PHY decoder core for the active port and a partial PHY decoder core for inactive ports. The partial core contains only the essential authentication logic needed for pre-authentication, excluding full video decoding functionality. This segmentation enables pre-authentication on inactive ports while minimizing the additional chip area required.
Solution Approach 2:
Instead of implementing full PHY decoder functionality on all ports, the system applies partial authentication action on inactive ports. The partial PHY decoder core performs only the necessary HDCP authentication tasks (key exchange, verification) without full video signal processing, achieving sufficient authentication capability with reduced circuitry and lower power consumption.
3Reliability
If full PHY decoder cores are implemented on all HDMI ports for complete authentication capability, then authentication reliability is maintained, but power consumption and chip area increase significantly
Solution Approach 1:
Different levels of decoder functionality are assigned to different ports based on their operational state. The active port receives full PHY decoder resources for complete video decoding and authentication, while inactive ports receive only partial authentication capability. This local differentiation ensures reliable authentication where needed while minimizing power consumption on ports that only require security verification.
Solution Approach 2:
The partial PHY decoder core is designed to be universally applicable to multiple inactive ports, sharing authentication resources across them. This multi-functional approach allows a single partial core to handle pre-authentication for several inactive ports sequentially or concurrently, reducing the total power consumption compared to having dedicated full decoder cores on each port.
Data Source
AI summary
A partial HDMI physical layer (“phy”) decoder core is used in an audiovisual (A/V) sink device to perform HDCP pre-authentication on inactive HDMI ports, so as to enable fast switching between HDMI ports. Whenever a source device is connected to the any HDMI port of the A/V sink device, HDCP authentication is performed on that port immediately, even if A/V data on that port is not being output to a user. As a result, when the user switches between HDMI channels, the output is available to the user instantly, without any HDCP-related delay. The A/V sink includes the partial HDMI phy decoder core in addition to a full HDMI phy decoder core. The full HDMI phy decoder core is used to extract and decode signals received on the active port. The partial HDMI phy decoder core is used to extract and decode only those HDMI signals received on an inactive port that are needed for pre-authenticating the inactive port.