A path in a switchable domain reports the wrong voltage after a power switch.
From PDVerse PrimeTime STA Interview Guide · pdVerse Mentor Guide
Ten-second Interview Answer
Work outward from the switch: report_power_switch for the On State, report_power_network for the topology through it, report_supply_net on the output net for its voltage states, then report_timing -voltage or pg_pin_info 's voltage_source on the cells.
Complete Technical Explanation
Trace it in the same order the tool itself resolves voltage. Start with report_power_switch and read the switch's On State expression, confirming that the control conditions you believe are active really do put it in the pass state you expect - if they do not, everything downstream is explained already. Next run report_power_network to see the actual net topology through the switch, which tells you whether the path from the input port to the cells you care about exists at all and goes where you think. Then report_supply_net on the switch's output net to inspect its voltage states and ranges. Finally, look at the cells themselves with report_timing -voltage, or read voltage_source through pg_pin_info, to see what voltage actually propagated to their PG pins. That last step distinguishes a wrong voltage from a fallback voltage. The single most common root cause in this scenario is that the switch's output net never had a set_voltage applied to it - the switch is fine, the topology is fine, but the terminating net carries no voltage, so the walk cannot resolve one and you get the UPF-029 message. Fix the voltage on the output net rather than hunting for a connectivity bug.
In Pd / Signoff
This is the standard debug ladder when a switchable-domain block reports delays that do not match its intended DVFS point. Each step narrows the failure to one layer - switch state, topology, net voltage, pin voltage - so you stop guessing. In a signoff script, checking that every switch output net has a set_voltage is worth doing pre-emptively before timing is released.
Common Trap
Assuming the switch or the connectivity is broken and rewriting UPF, when the switch output net simply has no set_voltage on it. That case reports as UPF-029 and shows up as PG pins whose voltage_source is not the net you expected, not as a missing connection.
Expect Next
What does UPF-029 tell you about the switch's output net, and which command fixes it?
Topic And Primetime Commands
Multivoltage / UPF & Power Domains. report_power_switch, report_power_network, report_supply_net, report_timing
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