This error message is due to incorrect nPERST pin placement in the PCIe® IP core. For example, you will get this error message if you use pin nPERSTL0 with the bottom left HIP in Cyclone® V devices. See the full error message below.
Error (175001): Could not place Hard IP
Info (175028): The Hard IP name: <top level instantiation>|altpcie_cv_hip_ast_hwtcl:dut|altpcie_av_hip_ast_hwtcl:altpcie_av_hip_ast_hwtcl|
altpcie_av_hip_128bit_atom:altpcie_av_hip_128bit_atom|arriav_hd_altpe2_hip_top
Error (10104): Unable to find a path between I/O pad and PINPERST port of PCI Express Hard IP.
Error (10151): "HIP_X1_Y15_N0" is not a legal location for "I/O pad" connected to PINPERSTN of PCI Express Hard IP.
Info (10371): 2 potential locations for I/O pad: PIN_W24, PIN_Y23.
Info (175029): 1 location affected
Info (175029): HIP_X1_Y15_N0
The correct mapping for nPERSTL0 and nPERSTL1 in Cyclone® V device is:
Bottom PCIe Hard IP --> nPERSTL1
Top PCIe Hard IP --> nPERSTL0
This mapping is opposite for Stratix® V and Arria® V devices where bottom PCIe Hard IP is associated with nPERSTL0, top PCIe Hard IP is associated with nPERSTL1.
