PCIe polarity inversion Setting

Well, I do see in the pci express base spec that all PCIe receivers are required to to support automatic polarity inversion(Rev1.1,page56). But meanwhile in the stratix ii gx transceiver architecure overview, Altera says:

"The positive and negative signals of a serial differential link are often

erroneously swapped during board layout. Solutions like a board re-spin

or major updates to the PLD logic can prove expensive. The receiver

polarity inversion feature is provided to correct this situation. An optional rx_invpolarity port is available in all single-width and

double-width modes except (OIF) CEI PHY to dynamically enable the

receiver polarity inversion feature..."

Now that automatic polarity inversion in the link layer is supported, the optional rx_invpolarity port seems unnecessary to most people. What is it designed for?

Despite of these, I believe that you're right. I don't need to explicitly change the megafunction files.