T1022 Serdes Configuration

[swatig]

I want to connect T1022 in PCIe x4 configuration and SGMII on other ports. So, I have to use 0x40 Serdes configuration. 0x40 configuration has one PCIe x2 , one PCIe x4 and SGMII on other ports. But even X1 PCIe is sufficient for my requirement. So, is it possible that I connect only lane 0 of the PCIe x2 port to the end point device and run PCIe in x1 mode ? Or is it necessary to connect both the lanes of PCIe port even for PCIe x1 to work?

[r8070z]

According to the PCIe specs it is possible connect only lane 0 of PCIe x2 port to PCIe x1 device. The PCIe Link Training and Status State Machine recognizes the maximum link width both devices support.