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The overall project goal of the ALSA System on Chip (ASoC) layer is to provide
-better ALSA support for embedded system on chip procesors (e.g. pxa2xx, au1x00,
+better ALSA support for embedded system-on-chip processors (e.g. pxa2xx, au1x00,
iMX, etc) and portable audio codecs. Currently there is some support in the
kernel for SoC audio, however it has some limitations:-
* Currently, codec drivers are often tightly coupled to the underlying SoC
- cpu. This is not ideal and leads to code duplication i.e. Linux now has 4
+ CPU. This is not ideal and leads to code duplication i.e. Linux now has 4
different wm8731 drivers for 4 different SoC platforms.
- * There is no standard method to signal user initiated audio events.
- e.g. Headphone/Mic insertion, Headphone/Mic detection after an insertion
- event. These are quite common events on portable devices and ofter require
- machine specific code to re route audio, enable amps etc after such an event.
+ * There is no standard method to signal user initiated audio events (e.g.
+ Headphone/Mic insertion, Headphone/Mic detection after an insertion
+ event). These are quite common events on portable devices and often require
+ machine specific code to re-route audio, enable amps, etc., after such an
+ event.
* Current drivers tend to power up the entire codec when playing
(or recording) audio. This is fine for a PC, but tends to waste a lot of
signals the codec when to change power states.
* Machine specific controls: Allow machines to add controls to the sound card
- e.g. volume control for speaker amp.
+ (e.g. volume control for speaker amp).
To achieve all this, ASoC basically splits an embedded audio system into 3
components :-
interface drivers (e.g. I2S, AC97, PCM) for that platform.
* Machine driver: The machine driver handles any machine specific controls and
- audio events. i.e. turing on an amp at start of playback.
+ audio events (e.g. turning on an amp at start of playback).
Documentation
git.openpandora.org / pandora-kernel.git / blobdiff