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USB4 is an industry standard that tunnels three different protocol specifications (PCIe, USB3 and DisplayPort) serially to a destination. DisplayPort (DP) tunneling over USB4 means DP protocol packets are converted into USB4 protocol packets and transferred over its fabric to a destination. Before the USB4 router sends the packets to its destination, they are converted back to DP protocol packets. In sum and substance, think of the USB4 fabric as a DP Repeater. The USB4 specification has rules that make this very efficient and guarantees no DP packets are lost.
There are two version options available in USB4:
USB4v1 supports DP1.4 specification features. USB4v2 supports DP2.x specification features with an option to fallback to USB4v1.
The diagram below shows a simple DP Tunneling configuration. A big part of DP tunneling is DP link training between the DPTX and DPRX devices. Training the physical layers of any serial protocol is a very complicated process. USB4 DP IN and DP OUT Adapters execute DP link training in one of the following modes:
USB4 has rules for each of the training modes of operation over DP Tunneling. For example, after reset, a DP Adapter operates in Non-LTTPR mode. For more details, refer to the USB4 specification to learn how it transitions to the other training modes.
Your team will need to identify what component or components to test. For example, if the design under test (DUT) is a Host Router, you will tunnel DP traffic through our USB4 Device Router VIP. Cadence’s DisplayPort DPTX and DPRX VIPs can be used as additional components for driving and receiving DP protocol packets. It will be important for the verification engineer to understand USB4 and DP protocols and configure the components correctly for successful verification and meeting their milestones.
Cadence USB4 VIP in our VIP catalog is a mature Verification IP solution. It has a host of features that include:
Among the many protocol features supported, Cadence’s USB4 VIP allows testing of layers separately. For example, if your DUT just needs to test the Transport layer, there is a configuration for it. If your DUT has a custom interface, i.e., PIPE interface, through a TLM (Transaction Level Modeling) configuration, the model will seamlessly tunnel USB4 protocol packets. These are just a few unique features that will meet your verification needs.
Cadence is an early adopter of the USB4 specification and has a mature and proven Verification IP and TripleCheck (TC) solution. Visit the Cadence USB4 VIP website for more details.