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Polarity reversal issue for PCIe interface of I.MX6

Question asked by SUNNY VAN on Mar 25, 2016
Latest reply on Mar 25, 2016 by igorpadykov

Hi All,


I may have made a mistake about Tx and Rx sigals' polarity  with my custom board running the Linux-3.0.35-2666-gbdde708.Connection diagram is shown below:


| —— |                                      |———|

| TxP  | <-------------------------->|  RxN  |

| TxN  | <-------------------------> |  RxP  |

| RxP  | <-------------------------> | TxN   |

| RxN  |<--------------------------> | TxP   |

|_____|                                      |_____|

Master Device                          EndPoint(I.MX6)


Now,the Master device can't find I.Mx6 in PCIe devece list. I know that generally PCIe standard should  allow inverting polarity for data and I find the descriptions in TP_HARDWARE_DESIGN_PCI_SMGIII for I.MX6:


Any channel can be connected with the positive and negative signals reversed

•Training sequence detects polarity inversion condition

•RX port is requiredto invert its signal polarity

According to this description, may I think that I.MX6'PCIe data interface also supports polarity reversal?

If so,how can I make it work?Add some code or modify some configuration?I'm afraid this board would not work

due to my silly mistake.