USB-C smartphone does not detect correctly as UMS

Polytropon freebsd at
Mon Oct 15 05:43:29 UTC 2018

On Sun, 14 Oct 2018 18:57:48 +0200, Tomasz CEDRO wrote:
> I have problems detecting a smartphone over USB-C - at first it only
> changes over the USB, then I switch it to be a USB Mass Storage, but I
> see no disk.. the same with different modes (i.e. Media Transfer,
> Picture Transfer, etc)..

In "mass storage" mode, a normal USB-backed da device should
appear (this is not the default for smartphones). Until all
involved stages of the device connection have been secured,
no da device will be accessible for tasks like mounting.

> DMESG shows only device connected and disconnected in a loop..

This seems to point to the core problem - a connection

> What is the problem here? VID/PID is unknown to the system or it does
> not present itself correctly as known USB endpoint?

This should not matter. Especially for PTP ("media transfer" modes)
a normal ugen device usually is sufficient.

> Any hints appreciated :-)

Check both the cable and the USB port on the computer.
Judging from your description, a connect/disconnect loop
suggests a connection problem. Also make sure your cable
is compatible (!) with both your device and your computer.

	Backwards Compatability. The physical USB-C connector
	isn't backwards compatible, but the underlying USB
	standard is. You can't plug older USB devices into
	a modern, tiny USB-C port, nor can you connect a
	USB-C connector into an older, larger USB port. But
	that doesn't mean you have to discard all your old


I'm not sure I'll it... ;-)

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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