Critical Warning: Pin mem_clk[0] must have its Cyclone® IV E Input Delay from Pin to Internal Cells set to 1

You might get this warning in the Timing Analyzer when implementing the DDR2 High-Performance Controller in Cyclone® IV devices using the Quartus® II software version 10.0 and earlier and if your design is implemented in hybrid mode. For example, DQ pins on both sides and row I/Os, and the “mem_clk” is placed on the side I/Os, the delay chain for the clock pin has to be set to 1. Therefore, you see this critical warning.

To remove this critical warning, add the following assignment to the QSF file:

set_instance_assignment -name PAD_TO_CORE_DELAY 1 -to mem_clk[0]

This problem is fixed in the Quartus® II software version 10.1.