It would be nice to have a standard userspace API for this but I'm not aware of anyone who's looked at it in detail and you start having to also take into account other algorithms that are running on the device so there's nothing to point people at right now and no real prospect of there being. I don't know if it's something we can resolve entirely in the kernel as I'm aware that some of the DSP implementations have non-trivial management code in userspace that they talk to which may mean that the standard API has to be a userspace one. There's also the difference between memory to memory implementations (which fit into a userspace chain much more readily) and tunneled implementations (which do need new infrastructure).
I think this'll get substantially easier to look at once the media controller API is merged and starts to be used in the audio subsystem.
Mark: I must be missing something here. Why would this media controller API make things simpler? Based on what was presented at LPC, I don't understand this last part. -Pierre