The HPD signal can operate in either a 2.5V or 1.8V I/O bank. By definition in the standard, it is a 5V signal.
For UltraScale+ devices supporting HP I/O banks, use the following constraints:
I/O Standard:
set_property IOSTANDARD LVCMOS18 [get_ports TX_HPD_IN]
set_property IOSTANDARD LVCMOS18 [get_ports RX_HPD_OUT]Sample Pin Assignments:
set_property PACKAGE_PIN A25 [get_ports TX_HPD_IN]
set_property PACKAGE_PIN A24 [get_ports RX_HPD_OUT]Board design and connectivity should follow HDMI Standard recommendations with proper level shifting.