Spurious headphone detection interrupts
Prior to enabling the serial console, I did use the headphone jack for audio output to my Hi-Fi. Assuming that headphone/speaker switching is done in software (it must be) then NetBSD must be handling the interrupt; it just isn't annotated. What's interesting with intrctl, is that you can watch interrupts as they happen in real time.

My wife does use headphones very often, so I am surprised that this interrupt hasn't occurred. But maybe she hasn't in the past 12 days. I'll see what happens when I plug them in.

I checked my wife's PBP, and the interrupt count does go up one, on every plug and every unplug of the headphones. I must have made a mistake earlier because before I plugged in the headphones, I checked the count again and it was 5. So either she had the headphones plugged in when booting 12 days ago (maybe?) or it also has a spurious source of interrupts.

Then I stupidly tried to see what would happen if I plugged the headphones into mine. Of course, I ended up at the DDB prompt with the system halted and no recourse, as I had no serial console handy.

Given the number of spurious interrupts that you have over the time, I don't know that I'd be too concerned, although it is a mystery worth solving. I don't know how hard it is to find the interrupt line to check it with a scope though. The trouble with noise on an interrupt line though is that hooking up the scope will influence the noise, or lack thereof. I wonder if Wi-Fi or bluetooth activity affects it.

Also food for thought: It may just be that you have a loose contact in the headphone jack. I wonder if tapping the case changes the count. I also wonder if you usually see even numbers.

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RE: Spurious headphone detection interrupts - by KC9UDX - 01-07-2021, 08:07 PM

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