Some bad news, Cambridge just informed me that they do not see this as a priority. So it is very unlikely, that the patch will end up in an official kernel any time soon. In fact, I believe it will never get done, linux users are not interesting enough for them.
Their quote: “From our own inbound communication from customers, we have not seen a high demand for this at the moment”.
So DSD direct support will remain limited to the x86 and Odroid N2/N2+ platform for a while to come.