Here’s what I see connecting a Librem 5 to a vanilla USB-A 3.0 port (not on a Librem 13; and computer is running Ubuntu) via an adapter, using the provided USB-C charging cable.
Librem 5 shows up on the host as Bus 999 Device 999: ID 1d6b:0104 Linux Foundation Multifunction Composite Gadget (bus and device numbers will be different for you)
Librem 5 tells the host that
- it can do networking of some kind (two different kinds?) but interface does not come up automatically (that’s probably a config issue - don’t know which end)
- it has a 1MB disk (mass storage class) -
File-Stor Gadget- wouldn’t get much of a file system on that (doesn’t appear to have a partition table and I didn’t dare partition it
) - maybe this is /var/lib/mass_storage_dummyon the Librem 5
Librem 5 goes into charging mode (LED is red) but does not seem to draw anywhere near the right amount of current - current as reported is all over the place - and appears to tell the host that the Librem 5 is self-powered (rather than bus-powered). I would tentatively blame the Librem 5 for this behaviour i.e. if it wanted to charge from a USB-A 3.0 port then it isn’t saying the right things.
Shows up for me as sda (I have no other USB/SCSI/SATA disks on that computer)
I think this confirms most of your observations. So it looks as if neither the USB-C port nor the USB-A port will work for charging the Librem 5.