USB/CDC Ethernet working?

[Guest modica]

I'm in the process of making the Google Nexus S work with a non-host capable rifleman radio. The device is 12Mbit USB and supports CDC mode (we were told it's EEM but it does not seem to be based on the packet headers we're seeing).

We know this works with the radios because we see Windows XP working and we can make it work with linux systems.

We have the OTG stuff sorted out and have gotten the phone/radio connection to come up. However when the phone xmits data, we see two bytes prepended to each packet. They appear to be option bits (mostly binary 0s).

We've double checked the buffers in the USB driver and they are correct. It appears the bytes are being added by the chip after the data is dma'd.

Does anyone know the USB core being used on the Nexus S? I'm looking for a chip spec and errata sheet. I've asked Samsung but based on the registration process, I expect it'll be a while before I hear back.

If anyone has Ethernet over USB happily working, I'd love to know what core you're using.

Steve