184.108.40.206.2. Transmitter Electrical Idle Generation
The PIPE interface block in Arria 10 devices puts the transmitter buffer in an electrical idle state when the electrical idle input signal is asserted. During electrical idle, the transmitter buffer differential and common mode output voltage levels are compliant with the PCIe* Base Specification 2.0 for both PCIe Gen1 and Gen2 data rates.
The PCIe specification requires the transmitter driver to be in electrical idle in certain power states.