How is error correction handled for existing nodes? For example, MIPI CSI-2 has an ECC field whereas A-PHY is CRC. Is there error correction for the packet header, and how does one detect packet headers?

There should be no need to transport any legacy packet headers; just use the A-PHY native mechanism.

How are packet retransmissions handled with data sources, such as cameras, continuously transmitting data?

The retransmission is handled at the A-PHY level and is transparent to the upper layer. A-PHY has a retransmission buffer to handle camera stream with up to three retries. The net application data throughput already takes care of the retransmission; no additional buffering is required at the MIPI CSI-2 level. More information can be found in the MIPI A-PHY specification.

Do eye diagrams have to be defined for the various speed gears?

For A-PHY Profile 1, which is based on NRZ Physical Medium Dependent (PMD), the A-PHY specification provides eye diagrams for all supported gears (G1-G3). For Profile 2, which is based on PAM, eye diagrams are not appropriate.

Power Spectral Density (PSD) limits are specified for all gears, along with requirements for supporting mandatory test modes for transmit jitter and linearity to fully characterize the transmitter.