Chapter 25
Advanced Linux Sound Architecture (ALSA) System
on a Chip (ASoC) Sound Driver
25.1 ALSA Sound Driver Introduction
The Advanced Linux Sound Architecture (ALSA), now the most popular architecture in
Linux system, provides audio and MIDI functionality to the Linux operating system.
ALSA has the following significant features:
• Efficient support for all types of audio interfaces, from consumer sound cards to
professional multichannel audio interfaces
• Fully modularized sound drivers
• SMP and thread-safe design
• User space library (alsa-lib) to simplify application programming and provide higher
level functionality
• Support for the older Open Sound System (OSS) API, providing binary compatibility
for most OSS programs
ALSA System on Chip (ASoC) layer is designed for SoC audio. The overall project goal
of the ASoC layer provides better ALSA support for embedded system on chip
processors and portable audio CODECs.
The ASoC layer also provides the following features:
• CODEC independence, allows reuse of CODEC drivers on other platforms and
machines.
• Easy I2S/PCM audio interface setup between CODEC and SoC. Each SoC interface
and CODEC registers its audio interface capabilities with the core.
• Dynamic Audio Power Management (DAPM). DAPM is an ASoC technology
designed to minimize audio subsystem power consumption no matter what audio-use
case is active. DAPM guarantees the lowest audio power state at all times and is
completely transparent to user space audio components. DAPM is ideal for mobile
devices or devices with complex audio requirements.
i.MX 6Solo/6DualLite Linux Reference Manual, Rev. L3.0.35_4.1.0, 09/2013
Freescale Semiconductor, Inc.
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