Receive – Retimer Related Issues - 3.1 English

DisplayPort 1.4 RX Subsystem Product Guide (PG300)

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3.1 English
This section contains debugging steps for issues related to Retimer. Proper operation of Retimer is essential for the training to complete successfully.
  • IIC checks:
    • Check if the IIC speed is 100 kHz or higher speed (1 MHz).
    • Check if the IIC writes are happening properly to the Retimer IC.
    • Check if the IIC writes are interrupt or polling based. If it is interrupt based, it is like calling an interrupt within another interrupt routine. Ensure this function is correct, or better to go with the polling mode, as Retimer IIC writes are supposed to happen at Retimer training events.
  • Until the training is done ensure only the TP1 and TP23 interrupts are enabled.
  • Ensure that you have no other software code in between TP1 interrupt to training done duration.
  • Check whether the TP1 and TP23 handlers are called correctly when the TP1 and TP23 interrupts are detected.
  • Probe the lnk_clk output and check the SI of the Clock is within the Phase Noise mask of the respective GT.
  • Avoid using PRINTF to monitor the Retimer configuration as the configuration must be completed as quickly as possible to meet the DisplayPort Standard requirements.