Why Intel® Quartus® Prime Software fitter failed to find a legal placement for IOPLL with Direct Interface Bus (DIB)? - Why Intel® Quartus® Prime Software fitter failed to find a legal placement for IOPLL with Direct Interface Bus (DIB)? Description The IOPLL reference clock is supplied by a source-synchronous clock that transfers from the other die via the Direct Interface Bus (DIB). However, there is an error from the Intel® Quartus® Prime Software while running the Fitter process. The Fitter failed to find legal placement for the IOPLL. Resolution The refclk of the IOPLL must use the global clock tree for the design to pass the fitter. Custom Fields values: ['novalue'] Troubleshooting 15012855156 False ['novalue'] ['FPGA Dev Tools Quartus® Prime Software Pro'] novalue 21.2 ['Stratix® 10 FPGAs and SoCs'] ['novalue'] ['novalue'] ['novalue']