Altclkctrl ip

Hi,

I am using ALTCLKCTRL to mux two clock signals. One of the signal is a PLL output and the other one is an from the clock pin.

I get an error from the fitter stating that it cannot place a global clock driver between the clock pin and the clkctrl block.

I also try to drive the input pins of clkctrl by a clock buffer output (another clkctrl block ; path wold be pinà clkctrl(buffer)àclkctrl(mux)). But it seems that this is illegal.

Can someone guide me with this?

Thanks,

Vittal