[libre-riscv-dev] Fwd: Connecting records to records?

[Jacob Lifshay]

try Record.connect?

https://github.com/m-labs/nmigen/blob/ff343d5cf0c57d1e21552e1033c0ae4bb13d78ae/nmigen/hdl/rec.py#L179

On Sun, Jul 14, 2019, 18:03 Samuel Falvo II <sam.falvo at gmail.com> wrote:

> I'm widening the audience to this question in the hopes that someone has
> some insight on this issue.  Originally sent to just Luke, but this seems
> like a question which is of more general interest.
>
> For my KCP53010 design, I'm looking to wrap a memory interface into a
> record so I can easily connect one record to another.  nmigen apparently
> doesn't know how to do this, however.  When I run a simulation, I see
> messages like this:
>
> (env3) [kc5tja at gienah cpu]$ python -m unittest -v test_add_store_cu
> test_add_store_cu_formally (test_add_store_cu.AddStoreCUTestCase) ...
>
> /home/kc5tja/projects/kestrel-3/trunk/cores/env3/lib/python3.6/site-packages/nmigen-0.1-py3.6.egg/nmigen/hdl/rec.py:84:
> DriverConflict: Signal '(sig opcode)' is driven from multiple fragments:
> top, top.dut; hierarchy will be flattened
>   self.fields[field_name] = Signal(field_shape, name=concat(name,
> field_name))
>
> This appears to be treated as a warning, rather than an error; still, it
> didn't happen before, and would like to correct the code so that this
> message isn't displayed anymore.
>
> Consider this contrived, simplified pseudo-code which I hypothesize is
> causing the problem:
>
> m_layout = [('a', 1, DIR_FANIN), ('b', 1, DIR_FANOUT)]
> s_layout = [('a', 1, DIR_FANOUT), ('b', 1, DIR_FANIN)]
>
> class Interface(Record):
>   def __init__(self, layout):
>     super().__init__(layout)
>
> x = Interface(m_layout) # master
> y = Interface(s_layout) # slave
>
> comb += x.eq(y)  # <-- appears to result in multiple drivers for the same
> signals when elaborated.
>
> In your experience, what is the proper approach to solving this problem?
> So far, I've found no evidence that this is even supported in the test
> cases in nmigen.  Am I missing something obvious?
>
> Per Luke's suggestion, I have tried the following as well:
>
> comb += Cat(x).eq(Cat(y))
>
> but this continues to yield the same error/warning message.
>
> Thanks for any help.
>
> --
> Samuel A. Falvo II
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