Chip-level RDC Closure: Expanded Case Study

Extended case study

Milestone review flags top-level RDC open count, subsystem handoff completeness, integration churn around Chip-level RDC Closure.

Background

Team believed crossings were stable until stress mode exposed intermittent anomalies.

Symptoms observed

• top-level RDC open count, subsystem handoff completeness, integration churn regression

• Mismatch between structural report and dynamic behavior

• Waiver debate under schedule pressure

Investigation timeline

1. Freeze design, reset, and tool configuration tags.

2. Reproduce failing scenario with minimized stimulus.

3. Map path/protocol/reset dependencies.

4. Classify root cause and containment options.

5. Execute minimal safe fix.

6. Run stress regression and review board.

Root cause

Root cause links to Chip-level RDC Closure: Chip-level RDC closure depends on clean reset intent handoff from IPs and alignment between subsystem sequencing assumptions.

Fix and validation

• Targeted RTL/protocol/reset correction

• Evidence refresh

• Signoff board decision

Lessons learned

• Treat waivers as temporary risk contracts

• Track owner and expiry

• Regression before closure

CASE STUDY — Chip-level RDC Closure
critical issues before / after / signoff

Crossing sequence under stress

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

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.

Principal CDC/RDC review addendum

Chip-level RDC closure depends on clean reset intent handoff from IPs and alignment between subsystem sequencing assumptions.

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