- Making all resets async since we cannot guarantee that we have a clock coming in from RX. This is needed due to the way we use a PLL for alignment. If we would have used a free running local clock this would have been different, but this would have required a FIFO for synchronization betwen the rx and rxdiv4 clock.
- Moving the clock block into the RX for modularity
- Making a specil rx soft reset (driven from sys_clk domain)
- Still there is a POR_reset so the link should wake up ok
- This is DEFINITELY the way to do things, sweep the delays and find the right value. No f'ing way to get these stupid FPGAs to work otherwise with the ridiculuosly over margined PVT nubmers they are running through the STAs. I understand they want to make the design bullet proof, but as a result designers are wasting countless hours overoptimzinng designs and being clever. So much performance is left on the table for expert users.
- Lesson: I/O design should be "self syncrhonizing". Only contraints in the design should be create_clk
- Made RX clock async, too tricky to guarantee that there clock is there. No way to do this if the clock sources are actually independent for RX/TX!
