psc: allow PSUs a grace period before requiring OK after enable. #1802
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hawkw
approved these changes
May 24, 2024
| ) => { | ||
| if deadline <= now { | ||
| // Take PSU out of probation state and start monitoring its | ||
| // OK line. |
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do you think it's worth including a ringbuf entry indicating that the PSU has come out of probation?
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I considered that, and I don't think it's worth it, since it's an unconditional event 1 second after On -- you'll either see it stay on, or you'll see it disable.
In fault injection testing I've seen _one time_ when the PSU failed to assert OK quickly after being enabled. This caused us to fault it and try again, at which point it worked. But, that has the effect of inserting an additional 5s delay on the fault recovery cycle, which in theory could repeat forever. This change adds a grace period after taking a faulted PSU out of fault status, before we start expecting it to assert OK. This mirrors the grace period we provide for newly inserted PSUs.
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In fault injection testing I've seen one time when the PSU failed to assert OK quickly after being enabled. This caused us to fault it and try again, at which point it worked. But, that has the effect of inserting an additional 5s delay on the fault recovery cycle, which in theory could repeat forever.
This change adds a grace period after taking a faulted PSU out of fault status, before we start expecting it to assert OK. This mirrors the grace period we provide for newly inserted PSUs.