[Libre-soc-bugs] [Bug 1004] FPGA bring up for platform definitions

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=1004

--- Comment #14 from Luke Kenneth Casson Leighton <lkcl at lkcl.net> ---
(In reply to Cesar Strauss from comment #13)
> I got Blinky to work on the Nexys Video!

hooray!

> It seems the leds didn't light up before because the 2,5V I/O buffers were
> only recently implemented in nextpnr-xilinx, and our version was too old.
> Updating it to current git master worked.
> 
> However this brings a massive regression when building ls2 for Arty...
> Routing no longer converges on that design, it goes on forever.

worth reporting, with repo instructions.


> Some options are:
> 
> 1) Don't do anything, and forget about the leds on the Nexys Video (also,
> Ethernet and HDMI).
> 2) Update nextpnr-xilinx to the commit that fixed the leds
> 3) Update nextpnr-xilinx to the last commit that still worked for ls2
> 4) Backport just the led fix, to the commit we currently use.
> 
> As for #3, I did find a fork of nextpnr-xilinx called openXC7
> (https://github.com/openXC7/nextpnr-xilinx), which seems actively developed,
> and whose latest release does work with both leds and ls2.

if that is easily a drop-in replacement, same commands, it may be
worth adding and commenting a link to this bugreport. they *may*
take merge/fixes upstream at some point

> In fact, for ls2
> on the Arty, it increases the maximum clock speed from 19 MHz to 25 MHz...

niice

> Also, someone would need to run the bitsream on a real Arty, to see if the
> update really works.

i have mine buried somewhere in a box... :)

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