P5020 PCIe lane reversal

[kyleb]

Hello, I am using a P5020 where the PCIe controller 1 is configured as a x4 and the PCIe controller 2 is configured as a x1. The PCIe x4 enumerates but the x1 does not. One possible reason is due to the x1 being connected to Lane H on the P5020 (signal names SD_RX07, SD_TX07, and their complements) rather than the perhaps preferred Lane E. NXP has indicated that the PCIe controller does have the ability to perform a lane reversal, but I do not see anything that indicates whether this is an automatic process or something that must be commanded via a register?

Thanks in advance!

[ufedor]

PEX2 is an x4 controller. Therefore, it should work with lane reversal with Lane 0 routed to Bank 1 Lane H.

[kyleb]

Thank you for the reply. Is lane reversal an automatic process or must the P5020 be directed (through a register write or similar) to do the lane reversal? I have not found much documentation on the subject. Thanks

[ufedor]

Yes, lane reversal is automatic.