ID:176594 Input clock of <name> PLL "<name>" must be fed by an I/O node -- PLL is in zero delay buffer or external feedback mode

CAUSE: You assigned the specified enhanced PLL to use zero delay buffer or external feedback mode. However, the Fitter cannot place the specified PLL because the input clock of the specified PLL is not an I/O node. Input clocks of PLLs in zero delay buffer or external feedback mode must must be fed by an I/O node.

ACTION: Modify your design so that an I/O node feeds the input clock port of the specified PLL.