What is the relationship between the channels and ports?

Hi all,
As you known, There are two TX channels and two RX channels in LMS7002M chip.Meanwhile, there are also two Limelight ports,port 1 and port 2. Could you pls tell me what is the relationship between channel A/B and Limelight port 1/2? if I only use channel A to receive signal, in this application, what is the Limelight port to be used?