Modified to use CLKBUF for chiplink rx clock

[donthus]

No description provided.

[tmagik]

I've built a version here https://github.com/tmagik/freedom/commits/donthus/freedom_microsemi_rebased, with submodule links to an older version of fpga-shells. With a 100mhz chiplink clock it passes timing and seems to be pretty stable.

What version of fpga-shells did you use this with?

[donthus]

I have used an updated fpga-shells at https://github.com/sifive/freedom/tree/freedom_microsemi_rebased (@ 8d5d73c) and created a pull request sifive/fpga-shells#54

[tmagik]

The version I have only works at 100mhz. At 125mhz chiplink clock, I see data corruption on reads from the gpu, nvme, and sata disks. @terpstra is there a way to determine the correct phase delay for the tx clock without hooking up a scope? Is this something that could vary across different boards?

[donthus]

We have tested https://github.com/tmagik/freedom/commits/donthus/freedom_microsemi_rebased along with the fpga shells at sifive/fpga-shells#54. We have used Libero v12.0 to build the design and we don't see any issue.

@tmagik can you try updated fpga shells at sifive/fpga-shells#54