MTP in Zephyr?

[peterz]

Hi

I'm migrating applications I wrote using SDK 17 to nrfConnect 3.0 with Zephyr.

I implemented USB devices with combined multiple USB classes. One of those classes was MTP which I had to implement myself because this was not supported. During this implementation I fully understood WHY this was not supported - it was a quite painful process.

Now I see that Zephyr support for multi class devices is getting improved.
I would like to ask for advice:

a) will MTP be supported or do I have to implement this myself again?

b) what is currently the recommended way to create multi class USB devices?

In case the Zephyr support for multi class devices isn't finised yet:
I prefer using experimental code over wait-until-stable

thanks a lot for your support and your precious time

Peter

[SwRa]

Hi Peter,

I believe MTP is not supported in the current or experimental Zephyr USB device stacks. The supported classes documented includes Audio, CDC ACM, CDC ECM, Mass Storage, HID, and Bluetooth HCI. See here: https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/connectivity/usb/device_next/usb_device.html#built-in_functions  So, it is likely that you would need to implement MTP yourself again. I will however check internally and confirm if that is the case and update here.

In case you need to implement it, it is recommended to use the new USB device stack: https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/connectivity/usb/device_next/usb_device.html#overview and https://docs.nordicsemi.com/bundle/ncs-latest/page/zephyr/connectivity/usb/device_next/api/index.html 

Regards,

Swathy