GMSL needs to operate in serial link mode (SEREN = 1) with valid PCLK presents.
To run the PRBS test, set DISHSFILT, DISVSFILT, and DISDEFILT to ‘1’, to disable glitch filter in the deserializer.
Then, set PRBSEN = 1 (0x04, D5) in the serializer and then in the deserializer. You can use the GMSL GUI and connect the I2C bus to your target board to start the PRBS.
To evaluate the link quality, usually we are checking the BER (bit error rate). Please refer attached slide.
Garmin or Geely should define the CL (Confidence Level) and N bit of error. Then conduct the PRBS test and check the PRBS error counter. The test time is heavily depends on CL, N bit error and GMSL serial link data rate.