Extended case study

Signoff review: power-state coverage, illegal-state count, and mode transition pass rate regressed after a low-power intent or sequence update related to Supply Sets & Power States.

Background

Previous build passed LP signoff matrix. New failures cluster around one state transition path.

Symptoms observed

• power-state coverage, illegal-state count, and mode transition pass rate regression

• Intermittent failures on transition

• Cross-team disagreement on root cause

Investigation timeline

1. Hour 0: freeze RTL, UPF, and PMU sequence tags

2. Hour 1: isolate failing transition and destination domain

3. Hour 2: verify policy bindings and crossing classification

4. Hour 3: replay waveform with state logs and controls

5. Hour 4: classify root cause and owner

6. Hour 5: apply minimal fix with rollback plan

7. Hour 6: run LP regression matrix and update release memo

Root cause

PST omitted one legal retention state, causing false illegal-state failures and masking a real wake-up path bug.

Fix and validation

• Policy or sequence fix with explicit ownership

• Re-run UPF supply-set block, PST table, and simulator power-state report

• Simulation + formal + implementation regressions

Lessons learned

• Transitions need timeline discipline

• Intent drift is often cross-tool

• Waivers must be bounded and documented

CASE STUDY — Supply Sets & Power States
coverage / violation count / post-fix stability

Transition under stress

MODE TRANSITION WAVEFORM — Supply Sets & Power States

time ---> 
save_req      ___/---------\____________________
iso_en        ________/----------------\________
switch_en     _____________/--------\___________
domain_vdd    -----------\____OFF____/----------
restore_req   ____________________/---\_________

Ordering errors are the most common LP escapes.

Low-power deep dive

Power intent must be explicit, reviewable, and tool-consistent from day one.

Concept diagram

POWER INTENT FLOW

architecture -> UPF objects -> tool binding -> verification evidence

Metric graph

INTENT QUALITY

bound policies      ████████████ high
stale references    ███          medium risk
missing states      ██           high risk

Reports and artifacts

• PST report

• domain map

• UPF lint

• policy binding summary

Mini case study

One missing PST entry blocked legal retention mode and caused false debug loops.

Debug branches

• Check legal state table first

• Audit policy binding IDs

• Freeze UPF revision tags

Senior review question

Ask: what transition evidence proves this topic is closed, and which owner signs it?

Key takeaways

• State transition context must accompany every low-power metric claim.

• Intent changes require simulation, formal, and implementation re-validation.

Common pitfalls

• Comparing results from mismatched UPF revisions.

• Assuming static checks replace transition validation.

• Shipping with aged waivers and unclear ownership.

Execution drill pack 1

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 1

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 2

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 2

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 3

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 3

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 4

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 4

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 5

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 5

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 6

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 6

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 7

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 7

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 8

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 8

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 9

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 9

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 10

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 10

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 11

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 11

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 12

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 12

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Execution drill pack 13

Use this pack to rehearse low-power closure on low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded: transition framing, policy ownership, implementation evidence, and release confidence.

Transition checklist

• State transition explicitly named with legal source/target states.

• Crossing and domain ownership are mapped and agreed.

• Policy controls are traced to always-on source logic.

• Waveform bookmarks align controls with state timestamps.

Review prompts

1. Which policy object is first to deviate from intent?

2. Which owner can apply the smallest reversible fix?

3. What regression matrix proves no collateral damage?

4. Which waiver conditions would still block release?

Evidence capsule

LP EVIDENCE CAPSULE 13

PATH: low-power/power-intent-fundamentals/supply-sets-and-states/case-study-expanded
STATE WINDOW: <from -> to>
POLICY OBJECT: <isolation / retention / shifter / switch>
OWNER: <name>
PRIMARY ARTIFACT: <report/waveform/formal result>
RELEASE DECISION: <close / bounded waiver / escalate>

Principal LP review addendum

UPF supply sets define electrical rails and legal state combinations; power states encode which domains may be ON, OFF, or RETAINED.

Metric: power-state coverage, illegal-state count, and mode transition pass rate