The RK3399 is indeed a great chip. I have an OrangePi RK3399 sitting on my desk right now in fact. But (at least when I last tried, last year) the mainline kern

The RK3399 is indeed a great chip. I have an OrangePi RK3399 sitting on my desk right now in fact. But (at least when I last tried, last year) the mainline kernel support for the OrangePi RK3399 isn't really there beyond booting, and the board documentation is poor-to-non-existent so it's unlikely to improve.