[Libre-soc-dev] arctic tern twin FPGA modules into talos2 server
luke.leighton at gmail.com
Fri May 20 21:44:42 BST 2022
i found an ECP5 PCIe PHY already partly done, in nmigen.
tim you will like this: reports state that they had stability problems bringing it up. it would only occasionally lock. sounds familiar, doesn't it?
(tim and i spent several weeks tracking down why GRAM would not stably lock. turns out that the DDR IOpads in nmigen did not have a proper RESET line coming in, consequently they lock to a *random* phase)
btw i suspect that now that RESET is properly introduced, the DDR IOPads are locking correctly... but it was only when they did *not* lock that they worked. urrr... and that's what the BitSlip module was there to fix: adjust the phase slightly.
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