(PG230) mentions that Transmit Buffer Bypass must be enabled for DisplayPort PHY Compliance.
Is it valid when using the DisplayPort 1.4 TX Subsystem for the VESA DP1.4 PHY compliance test?
TX buffer bypass helps to avoid inter-pair skew. This is require in the DP1.2a Compliance test in order to pass the Inter-pair Skew test.
In DP1.4 PHY compliance (VESA DP1.4 PHY CTS), the Inter-pair skew is changed to informative which means that it is not required for DP1.4 compliance test.
The DP1.4 PHY CTS mentions that the informative test can be useful for debugging purposes in case the interoperability test fails.
However, it is also mentioned that it is unlikely that inter-pair skew could be a significant reason for non-interoperability.