CDC / RDC · All levels

CDC Waiver Policy: Expanded Case Study

Expanded Case Study for CDC Waiver Policy.

Extended case study

Milestone review flags open critical waivers, stale waiver age, waiver quality score around CDC Waiver Policy.

Background

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

Symptoms observed

open critical waivers, stale waiver age, waiver quality score regression
Mismatch between structural report and dynamic behavior
Waiver debate under schedule pressure

Investigation timeline

Freeze design, reset, and tool configuration tags.
Reproduce failing scenario with minimized stimulus.
Map path/protocol/reset dependencies.
Classify root cause and containment options.
Execute minimal safe fix.
Run stress regression and review board.

Root cause

Root cause links to CDC Waiver Policy: Waivers are controlled risk acceptances and must include mechanism justification, containment evidence, and ownership for periodic revalidation.

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

diagram

CASE STUDY — CDC Waiver Policy
critical issues before / after / signoff

Crossing sequence under stress

diagram

CROSSING FLOW — CDC Waiver Policy

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

Key metric: open critical waivers, stale waiver age, waiver quality score

CDC/RDC deep dive

Signoff is an evidence governance problem across teams.

Concept diagram

diagram

CDC SIGNOFF LOOP

analysis -> triage -> fix/waive -> review gate -> dashboard

Metric graph

diagram

CRITICAL OPEN COUNT

week1 34
week2 22
week3 10
week4 0

Reports and artifacts

critical by owner
waiver quality
review gate status
closure trend

Mini case study

Pass rates improved while critical waivers aged out of policy; dashboard exposed hidden risk.

Debug branches

Separate quality from quantity metrics
enforce waiver expiry
run gate checklists consistently

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

Waivers are controlled risk acceptances and must include mechanism justification, containment evidence, and ownership for periodic revalidation.

Metric: open critical waivers, stale waiver age, waiver quality score

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