hiya, not sure if this is firmware or kernel or overlay but figured i'd start here! :)

I'd like to show people how to use older installs of raspbian on their Pi Zero, its been asked a few times and i expect it'll come up more soon. I noticed that if you replace just the firmware files on the card, it does boot firm/kernel just finebut you get

WARN::dwc_otg_handle_mode_mismatch_intr:68: Mode Mismatch Interrupt: currently in Device mode

forever, if there's nothing plugged into the Zero's microUSB.
It seems like there's an OTG pin (which is super cool because of course you could have the zero act as a device) but its in the wrong state when no USB device is plugged in. So i guess my question is: if this OTG pin is floating, which makes the Zero think its a USB device, how does one set the pulldown/up, is this done in firmware, overlay, kernel...?