The implementation was causing regressions on actual designs, rework done:
- Only keep a common iteration loop as before.
- Add iteration on CLKO dividers (to fall in the VCO range).
- Do the iterations as before, if while doing it we find a clock suitable for feedback: just use it.
- If no feedback clock has been found: create it (if at least one free output available, if not raise an error).
Dynamically adjusting the phase of a feedback will cause it to unlock.
The phase adjust ports are shared by all the outputs, so there is no
technical way to prevent this. Allow the user to indicate that they
will not adjust a clock when requesting an output by setting
uses_dpa=False, and only consider those that the user has promised not
to use.
Florent Kermarrec
George Hilliard