Hey folks I have a design where I can scale the size of the

Question

Hey folks I have a design where I can scale the size of the circuit add more units At some point as I increase the amount of circuitry the design becomes unable to synthesize with OpenLane reporting too much congestion Does anybody know any parameters I could tweak to possibly help with this Would reducing the density by decreasing `PL TARGET DENSITY` and `FP CORE UTIL` help or are those irrelevant to this congestion

Matthew Guthaus · Answer

For the first do you mean PL TARGET DENSITY That causes placement to spread cells out to meet local density The FP CORE UTIL determines how much area a relative floorplan should be compared to the cell area It doesn t matter if you have an absolute floorplan size Last your may want to restrict the GLB ROUTE ADJUSTMENT which will reserve some global route tracks to spread out wires So yes all if the above

Peter Schmidt-Nielsen · Answer

Yes sorry I meant `PL TARGET DENSITY` Cool thanks I ll try `GLB ROUTE ADJUSTMENT`

Peter Schmidt-Nielsen · Answer

Actually apologies I checked my logs more carefully the too much congestion was an error I was getting before now I seem to be getting an error like the following Basically TritonRoute will run its 64 optimization passes and then fail with ``` ERROR There are violations in the design after detailed routing ERROR Total Number of violations is 9``` Would tweaking `GLB ROUTE ADJUSTMENT` be your advice for this too I honestly don t know which steps run in which order and therefore which failures cannot be helped by which options

Peter Schmidt-Nielsen · Answer

Also just to be 100 sure I assume by `GLB ROUTE ADJUSTMENT` you re referring to `GLB RT ADJUSTMENT` It looks like the default value is 0 least reduction so I assume there s not much I can do by adjusting that

Matthew Guthaus · Answer

Yes that s what I meant This reserves space in the global routing grid which will make the detailed routing easier By default it doesn t reserve reduce any so the global routing is at full capacity and can be hard to detailed route You can also do this for specific layers

Mitch Bailey · Answer

< Peter Schmidt Nielsen> If you have the time you might also try increasing the iterations I hear the default limit is 64

Peter Schmidt-Nielsen · Answer

Thanks folks for the suggestions Setting `GLB RT ADJUSTMENT` to values like 0 2 0 5 and 1 didn t have any discernible effect but I increased `GLB RT OVERFLOW ITERS` to 200 and `ROUTING OPT ITERS` to 256 and things got a tad better