Hi, @joanxie
According to Data sheet IMX7DCEC.pdf, in table 99 "iMX7Dual 12x12mm supplies contact...", there are PCIE_VP (AB13 Ball) and PCIE_VPH (Y15 Ball), but no PCIE_VP_TX.

On the other hand, table101 "iMX7Dual 19x19mm supplies contact...", There is PCIE_VP_TX (AA11 pins).

I use 12 x 12mm package. So that, I can not connect supply power to PCIE_VP_TX ball.