diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2008-01-31 23:16:28 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-01-31 23:16:28 (GMT) |
commit | e1a9c9872dd004617555dff079b357a6ffd945e9 (patch) | |
tree | c34779e59712ff345f8e4ee97e74086a85b34974 /Documentation/sound/alsa/soc/overview.txt | |
parent | fcc3ff4f9d695a80dc6e6058e0d631a3026ed4c3 (diff) | |
parent | 2ecba4ffbbc6c85fce8c3878514be415edace413 (diff) | |
download | linux-fsl-qoriq-e1a9c9872dd004617555dff079b357a6ffd945e9.tar.xz |
Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/perex/alsa
* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/perex/alsa: (299 commits)
[ALSA] version 1.0.16rc2
[ALSA] hda: fix Mic in as output
[ALSA] emu10k1 - Another EMU0404 Board ID
[ALSA] emu10k1 - Fix kthread handling at resume
[ALSA] emu10k1: General cleanup, add new locks, fix alsa bug#3501, kernel bug#9304.
[ALSA] emu10k1 - Use enum for emu_model types
[ALSA] emu10k1 - Don't create emu1010 controls for non-emu boards
[ALSA] emu10k1 - 1616(M) cardbus improvements
[ALSA] snd:emu10k1: E-Mu updates. Fixes to firmware loading and support for 0404.
[ALSA] emu10k1: Add comments regarding E-Mu ins and outs.
[ALSA] oxygen: revert SPI clock frequency change for AK4396/WM8785
[ALSA] es1938 - improve capture hw pointer reads
[ALSA] HDA-Intel - Add support for Intel SCH
[ALSA] hda: Add GPIO mute support to STAC9205
[ALSA] hda-codec - Add Dell T3400 support
[ALSA] hda-codec - Add model for HP DV9553EG laptop
[ALSA] hda-codec - Control SPDIF as slave
[ALSA] hda_intel: ALSA HD Audio patch for Intel ICH10 DeviceID's
[ALSA] Fix Oops with PCM OSS sync
[ALSA] hda-codec - Add speaker automute to ALC262 HP models
...
Diffstat (limited to 'Documentation/sound/alsa/soc/overview.txt')
-rw-r--r-- | Documentation/sound/alsa/soc/overview.txt | 42 |
1 files changed, 22 insertions, 20 deletions
diff --git a/Documentation/sound/alsa/soc/overview.txt b/Documentation/sound/alsa/soc/overview.txt index c47ce95..1e4c6d3 100644 --- a/Documentation/sound/alsa/soc/overview.txt +++ b/Documentation/sound/alsa/soc/overview.txt @@ -1,25 +1,26 @@ ALSA SoC Layer ============== -The overall project goal of the ALSA System on Chip (ASoC) layer is to provide -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:- +The overall project goal of the ALSA System on Chip (ASoC) layer is to +provide better ALSA support for embedded system-on-chip processors (e.g. +pxa2xx, au1x00, iMX, etc) and portable audio codecs. Prior to the ASoC +subsystem there was some support in the kernel for SoC audio, however it +had 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 - different wm8731 drivers for 4 different SoC platforms. + * Codec drivers were often tightly coupled to the underlying SoC + CPU. This is not ideal and leads to code duplication - for example, + Linux had different wm8731 drivers for 4 different SoC platforms. - * There is no standard method to signal user initiated audio events (e.g. + * There was 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 - power on portable devices. There is also no support for saving power via - changing codec oversampling rates, bias currents, etc. + * Drivers tended to power up the entire codec when playing (or + recording) audio. This is fine for a PC, but tends to waste a lot of + power on portable devices. There was also no support for saving + power via changing codec oversampling rates, bias currents, etc. ASoC Design @@ -31,12 +32,13 @@ 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 it's audio interface capabilities with the core and are - subsequently matched and configured when the application hw params are known. + * Easy I2S/PCM audio interface setup between codec and SoC. Each SoC + interface and codec registers it's audio interface capabilities with the + core and are subsequently matched and configured when the application + hardware parameters are known. * Dynamic Audio Power Management (DAPM). DAPM automatically sets the codec to - it's minimum power state at all times. This includes powering up/down + its minimum power state at all times. This includes powering up/down internal power blocks depending on the internal codec audio routing and any active streams. @@ -45,16 +47,16 @@ features :- 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 amplifier). To achieve all this, ASoC basically splits an embedded audio system into 3 components :- * Codec driver: The codec driver is platform independent and contains audio - controls, audio interface capabilities, codec dapm definition and codec IO + controls, audio interface capabilities, codec DAPM definition and codec IO functions. - * Platform driver: The platform driver contains the audio dma engine and audio + * Platform driver: The platform driver contains the audio DMA engine and audio interface drivers (e.g. I2S, AC97, PCM) for that platform. * Machine driver: The machine driver handles any machine specific controls and @@ -81,4 +83,4 @@ machine.txt: Machine driver internals. pop_clicks.txt: How to minimise audio artifacts. -clocking.txt: ASoC clocking for best power performance.
\ No newline at end of file +clocking.txt: ASoC clocking for best power performance. |