Chip-level RDC Closure

What this topic teaches

Chip-level RDC Closure focuses on closing CDC/RDC risk with mechanism-level reasoning. Chip-level RDC closure depends on clean reset intent handoff from IPs and alignment between subsystem sequencing assumptions. Senior signoff depends on proving behavior with targeted evidence, not just clearing tool warnings.

The senior-engineer question

When top-level RDC open count, subsystem handoff completeness, integration churn regresses, can you classify the hazard, identify accountable owners, and choose the smallest fix or waiver backed by evidence?

CDC/RDC SIGNOFF FLOW — Chip-level RDC Closure

crossing inventory + reset map
          |
          v
crossing classification (level/pulse/bus/reset)
          |
          v
structure + protocol + reset checks
          |
          v
critical issues + waiver review
          |
          v
fix / validate / regress / signoff

Picture the crossing behavior

Draw the behavior before touching tools. These visuals are the expected whiteboard baseline for reviews and interviews.

SoC reset map

IP A reset tree ---IP B reset tree ----+--> SoC dependency graph
IP C reset tree ---/

Top-level closure fails when IP assumptions conflict.

Crossing sequence

CROSSING FLOW — Chip-level RDC Closure

source clock domain -> launch signal -> crossing structure -> destination sample
      |                    |                 |                    |
   source FF           protocol           sync / fifo         destination FF

Key metric: top-level RDC open count, subsystem handoff completeness, integration churn

Ownership layers

CDC/RDC OWNERSHIP LAYERS — Chip-level RDC Closure

layer                 owns                            common failure
------------------    -----------------------------   -----------------------------
design intent         crossing architecture           wrong topology selected
protocol semantics    req/ack, fifo, ordering        liveness/deadlock bugs
reset behavior        assert/deassert sequencing      boot instability
analysis setup        tool rules + waivers            false confidence
signoff governance    risk acceptance + dashboard     stale critical waivers

Evidence to collect

• Primary metric: top-level RDC open count, subsystem handoff completeness, integration churn.

• Primary artifact: SoC reset map, subsystem waiver list, integration closure report.

• Owners to involve: SoC lead, RDC lead, IP owners.

• At least one reproducer tied to mode/reset/traffic context.

• Decision record: fix, waive, or escalate with rationale.

Ownership map

OWNERSHIP MAP — Chip-level RDC Closure

artifact                  owner
----------------------    -------------------------
design intent           SoC lead
verification evidence   RDC lead
signoff decision        IP owners

Every open CDC/RDC issue needs one accountable owner before waiver or fix.

Subpages in this topic

Each topic includes mechanism, I/O contract, metrics, debug, worked example, pitfalls, interview drills, checklist, theory, design tradeoffs, expanded case study, walkthrough, comparison matrix, software view, and silicon impact.

Key takeaways

• Classify crossing/reset hazards before proposing fixes.

• Pair structural results with protocol/reset behavioral proof.

• Treat waivers as bounded risk contracts, not cleanup shortcuts.

Common pitfalls

• Mass-waiving warnings near tapeout.

• Assuming local IP cleanliness guarantees SoC behavior.

• Skipping reconvergence and reset stress after CDC fixes.

CDC/RDC deep dive

RDC closure must connect IP assumptions to SoC reality.

Concept diagram

RDC CLOSURE

IP reset intent + SoC sequencing -> structural checks -> dynamic stress -> signoff

Metric graph

MILESTONE READINESS

M-2 55%
M-1 82%
M0  100%

Reports and artifacts

• top-level RDC opens

• reset simulation coverage

• chip integration blockers

• waiver backlog

Mini case study

Each IP was locally clean, but top-level sequencing violation created cross-subsystem boot intermittency.

Debug branches

• Audit subsystem assumptions

• stress chip-level reset scenarios

• close ownership gaps

Senior review question

Ask: what evidence proves this risk is closed for silicon, not just tool-clean?

Key takeaways

• State crossing class, assumptions, and owner with every issue.

• Run structural and dynamic regressions after each fix.

Common pitfalls

• Treating all warnings as equivalent risk.

• Waiving issues without containment evidence.

• Skipping reset and reconvergence stress after CDC fixes.