audio: add support for deep PCM buffering
Implement one output stream with short buffers and
one output stream with deep buffers.
The stream with short buffers is selected for most use cases and
provides short latency. It uses TONES_DL port and IOCTL write mode.
The stream with deep buffers is used for music playback.
It uses MM_DL port and MMAP NOIRQ write mode.
The deep buffer stream is not used when the device selection is
BT SCO, HDMI or SPDIF.
The echo reference is only taken from the short buffer stream.
Change-Id: I60ef720e52e96970b8b6618f9f43f24baadce60b
2 files changed
