I'm currently trying to get USB OTG to work, so,I can use the gadget module g_serial.
I've stumbled across this post where someone managed to do that, but I had no success so far. There is also very little information how he did it. I've tried raspbian and debian so far, but had no luck with either of them. Right now I'm installing ubuntu, because on the older BPI models OTG was directly supported by Bananian, which is based on Ubuntu, but I don't have much hope. I also compiled the kernel with the activated OTG settings, but it didn't change a thing.
Anyhow, if someone was able to get OTG working, I'd be grateful for every hint you can provide!