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Some RAMB36E1 parameter modes aren't getting encoded properly. #2

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litghost opened this issue Mar 29, 2021 · 2 comments
Open

Some RAMB36E1 parameter modes aren't getting encoded properly. #2

litghost opened this issue Mar 29, 2021 · 2 comments
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FPGA interchange bootstrapping

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@litghost
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After the most recent RapidWright patch to getPinMappingsP2L, some RAMB36E1 parameter modes aren't generating valid encodings in the FPGA interchange. Unclear if this a problem with the schema or the encoder.

The particular parameter set that is problematic is WRITE_WIDTH_A=0 RAM_MODE=TDP. Other WRITE_WIDTH_A values, and WRITE_WIDTH_A=0 RAM_MODE=SDP encode fine.
@litghost litghost added this to To Do in FPGA interchange bootstrapping via automation Mar 29, 2021
@clavin-xlnx
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clavin-xlnx commented Mar 29, 2021 •
edited by unfurl-links bot

My guess is that the Interchange needs to be augmented to include multiple parameters that affect a specific pin mapping:
https://github.com/SymbiFlow/fpga-interchange-schema/blob/f537a57fd7af091aabb776cb888f103b2b29349b/interchange/DeviceResources.capnp#L278

In this case, for example, WEAU0 gets GND by default, but when WRITE_WIDTH_A=0 AND RAM_MODE=TDP are both set, then WEAU0 gets WEA[0].

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@litghost
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litghost commented Mar 29, 2021 •
edited by unfurl-links bot

My guess is that the Interchange needs to be augmented to include multiple parameters that affect a specific pin mapping:
https://github.com/SymbiFlow/fpga-interchange-schema/blob/f537a57fd7af091aabb776cb888f103b2b29349b/interchange/DeviceResources.capnp#L278

I'd like to avoid multiple parameter matching like that if possible.

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