Powering the devkit through USB works fine with the cable and the power adapter… but we lost the usb now.
I’ve looked for a way to also have an USB connection to the device, so I searched the internet and found a so called BC1.2-USB charging hub that provides both normal usb functionality and enough power to feed the devkit in full operation mode.
The usb hub i tested here is: https://www.orico.shop/en/orico-usb-30-hub-with-bc-12-charging-function-7-po.html wich does 7 ports 1.5a each port, instead of the default of 900ma or as my imac does only 500ma wich is insufficient.
I can confirm that the devkit is full working mode and usb is visible on my osx device:
$ ioreg -p IOUSB
—8<---- cut away other devices — 8<------
±o USB2.0 Hub @14300000 <class AppleUSBDevice, id 0x100001825, registered, matched, active, busy 0 (1 ms), retain 18>
±o USB2.0 Hub @14310000 <class AppleUSBDevice, id 0x10000183d, registered, matched, active, busy 0 (1 ms), retain 18>
±o Gadget Serial v2.4@14311000 <class AppleUSBDevice, id 0x100001950, registered, matched, active, busy 0 (1 ms), retain 19>
To connect a serial terminal to the usb port use the screen command as found in Linux and OsX. For OsX look here: Mini howto: connect a serial terminal to the DevKit USB port in OsX
Or for linux: https://developer.puri.sm/Librem5/Development_Environment/Boards/imx8.html#usb-console
Hope it helps