Debug Access Port: Review Checklist

Review checklist

Review Checklist for Debug Access Port focuses on debug access latency, security lock compliance, bring-up access reliability. The goal is to convert metric movement into mechanism, owner, and release decision.

• Run tags and scenario context are explicit.

• Constraints and legality assumptions are documented.

• Quality, timing, and test-power checks are included.

• Diagnosis evidence supports residual-risk decision.

• Owners signed: security owner, bring-up owner, DFT owner.

Signoff ownership

OWNERSHIP MAP - Debug Access Port

artifact              owner
----------------      -----------------
architecture/report security owner
constraints/setup   bring-up owner
physical/test       DFT owner

Name an owner for each failing metric cluster.

DFT deep dive

Boundary scan and JTAG are board-level contracts, not just RTL features.

Concept diagram

JTAG ACCESS

TAP controller -> instruction register -> boundary/data register -> board test/debug

Metric graph

BOARD TEST READINESS

instruction coverage vs pin controllability

Reports and artifacts

• TAP compliance report

• boundary cell coverage matrix

• EXTEST/INTEST results

• debug lock policy log

Mini case study

Board bring-up blocked by pinmux override in one mode; TAP instruction decode and package table alignment fixed path.

Debug branches

• Verify TAP state transitions

• Audit package pin ownership

• Check security lifecycle lock behavior

Senior review question

Ask: what evidence proves this DFT decision is safe for production?

Key takeaways

• State metric, lot/corner context, and pattern tag with every claim.

• Treat timing, power, and quality as one signoff problem.

Common pitfalls

• Chasing coverage without legality checks.

• Ignoring test-power side effects of pattern changes.

• Debugging silicon without reproducible tags.

Principal DFT review addendum

Debug access over JTAG must balance bring-up visibility with production security and lifecycle lock policy.

Metric: debug access latency, security lock compliance, bring-up access reliability