Legal and Illegal PST Transition Checks: Review Checklist

Review checklist

Review Checklist for Legal and Illegal PST Transition Checks is anchored on Illegal transition escape rate, transition-checker latency to first error, and percentage of legal arcs exercised with pass/fail evidence.. Convert observations into mechanism-backed and owner-bound actions.

• Scope, mode, seed, and metadata are explicit.

• Mechanism classification is evidence-backed.

• Ownership and rollback boundary are documented.

• Validation matrix includes deterministic replay checks.

• Owners signed: DV assertion owner, power controller RTL lead, firmware sequencing owner, formal verification owner, SoC integration owner.

Low-power verification deep dive

Power-state correctness is a protocol contract: legal transitions, robust sequencing, and safe concurrent event handling.

Concept diagram

PST CONTROL LOOP

state request -> legality check -> handshake sequencing -> mode entry -> monitored exit

Metric graph

STATE RISK MIX

illegal transitions     ██████
sequence race bugs      █████
stable mode paths       ████████

Metrics and artifacts to collect

• PST legality matrix

• illegal transition histogram

• entry/exit handshake coverage

• mode sequencing anomaly log

Mini case study

A sporadic low-power failure closed only after proving a wake-versus-thermal race in PMU transition sequencing.

Debug branches

• Validate legal state graph first.

• Stress concurrent control events and asynchronous wakeups.

• Bind fixes to explicit transition and owner contracts.

Senior review question

Ask: what exact low-power transition boundary failed first, and which artifact proves the closure claim reproducibly?

Key takeaways

• Tie each LPV claim to a concrete transition boundary and one proving artifact.

• Prefer minimal reversible fixes with explicit owner and rollback criteria.

Common pitfalls

• Treating power-aware failures as random before boundary classification.

• Waiving X-prop failures before proving impact and root cause.

• Declaring closure without deterministic replay across key modes.

Principal LPV review addendum

Legal and Illegal PST Transition Checks should be reviewed as a transition integrity system, not just isolated checks.

Use Illegal transition escape rate, transition-checker latency to first error, and percentage of legal arcs exercised with pass/fail evidence. as alarm and Transition-arc checker specification with guard predicates, timeout rules, and illegal-arc diagnostics taxonomy. as proof.

Power-state verification is a protocol verification problem: legal transitions, ordering contracts, and corner-case concurrency. Closure quality comes from reproducible evidence and explicit owners.