This problem affects DDR2, DDR3, and LPDDR2 products.
In Arria V and Cyclone V devices, you can bond two hard memory controllers to increase their bandwidth. To use bonding, you must generate both hard memory interfaces with Export Bonding Interface turned on, and then connect the bonding signals between the two interfaces in the RTL code.
Bonding is supported only for hard memory controllers configured with one port. Do not use the bonding configuration when there is more than one port in each hard memory controller.