Rockbox

I'm not able to recreate the 'pause on headphone unplug' thing with the current code (3dc4f81).

Can you retest now, please?

I updated to 3dc4f81 and tried again, but 'pause on headphone unplug' still was not working properly on either X3 that I tested.
Something I noticed: when said setting is set to 'Pause', it does pause whenever I unplug Line Out (but not the headphone jack). Setting it to 'Pause and Resume' neither pauses nor resumes when plugging in or unplugging either output jack.

I set mine to pause+unause, and it worked as expected with the 3dc4f81 build, plugging/unplugging the headphones. (nothing was in the line out jack)

So.. I don't know what to say at this point…

there are two known hardware variations, although there is no known way to identify them in software.

Does yours have a button labeled 'ESC' on it?

No, neither of mine have a button labeled ESC. I looked up an image of it, the button that would be 'ESC' is labeled as 'BACK' underneath the button with a pictogram of a house above it.

Were you able to reproduce the problem I described with 'Disable resume on startup if no headphones plugged' on your X3?

In the last couple of days more work has gone into the button code – including the headphone jack detection that had false positives. Can you retest on your unit with the latest nightly or dev build?

I updated to 14c2f55ab3 (September 10), but it doesn't seem fixed.
Pause on headphone unplug still does nothing. Disable resume on startup if no headphones plugged isn't working, and now it doesn't resume if something is plugged into Line Out either.

you might try renaming your .rockbox directory and starting fresh from the latest dev build

be sure to remember to set headphone pause / resume

I'm getting flawless pause\resume on the HP port its not so great on LO though its about 75%
if you can verify the HP part works for you now I'll try something similar with LO

I updated to the 2020-09-17 build (2df3a5b04c), new .rockbox folder.
After enabling it, 'pause and resume on headphone unplug' works all the time for LO but never for the headphones.
Also, 'disable resume on startup if no headphones plugged' doesn't seem to work for either LO or headphones (it starts paused no matter what is plugged in).

the headphone one sounds like a HW issue do you see status of HP plug unplug in the debug menu under 'IO ports'

With nothing plugged in, the line labelled GPIOB has a value of eff077fc. Plugging in LO changes it to eff067fc. Plugging in the headphones doesn't seem to change it.
Could I just have terrible luck and both of them arrived with broken headphone detection? I just tested the original OS and it doesn't seem to pause on unplug for headphones either.

there is an actual entry for HP and LO click next till you see it
that is a mirror of the input the detection code uses to make a decision

edit: if you don't see it there either its on a different GPIO on your unit and or broken

Sorry, I was unaware.
It shows my headphones as removed no matter what is plugged into it, but it does detect LO fine. I tried looking at the other GPIO values as I plugged and unplugged the headphone port, but none of them seemed to be affected by it.

Unfortunately it sounds like you have a faulty headphone port ot someone forgot the sense pin
have you tried another set of headphones?