Composite audio driver

The Composite interface is a FIDL protocol exposed by audio drivers. The Composite interface is generic and allows the configuration of various audio hardware types including those supported by the StreamConfig, Dai and Codec FIDL interfaces. The Composite interface is more generic and provides more flexible routing within audio subsystems.

In this protocol, ring buffer and DAI endpoints are configured based on the topology exposed via the Audio Signal Processing APIs. In particular, endpoints represent the hardware that is abstracted, specifically the number of ring buffers and DAI interconnects. Audio hardware that can be represented by other audio driver types (StreamConfig, Dai, Codec) can instead be represented with a Composite driver. For example, a Composite driver can represent a Codec with a topology that has zero RingBuffer endpoints and one DAI interconnect endpoint.

When an audio driver provides the Composite interface, its client is responsible for configuring the hardware, including data topology. Driver responsibilities include using the SignalProcessing protocol to enumerate the topologies and capabilities supported by the hardware it abstracts.

The Composite FIDL protocol is defined at composite.fidl.