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Diffstat (limited to 'Documentation/sound/alsa/soc/codec.txt')
| -rw-r--r-- | Documentation/sound/alsa/soc/codec.txt | 53 |
1 files changed, 27 insertions, 26 deletions
diff --git a/Documentation/sound/alsa/soc/codec.txt b/Documentation/sound/alsa/soc/codec.txt index 1e766ad0ebd1..1e95342ed72e 100644 --- a/Documentation/sound/alsa/soc/codec.txt +++ b/Documentation/sound/alsa/soc/codec.txt @@ -9,7 +9,7 @@ code should be added to the platform and machine drivers respectively. Each codec driver *must* provide the following features:- 1) Codec DAI and PCM configuration - 2) Codec control IO - using I2C, 3 Wire(SPI) or both API's + 2) Codec control IO - using I2C, 3 Wire(SPI) or both APIs 3) Mixers and audio controls 4) Codec audio operations @@ -19,7 +19,7 @@ Optionally, codec drivers can also provide:- 6) DAPM event handler. 7) DAC Digital mute control. -It's probably best to use this guide in conjunction with the existing codec +Its probably best to use this guide in conjunction with the existing codec driver code in sound/soc/codecs/ ASoC Codec driver breakdown @@ -27,8 +27,8 @@ ASoC Codec driver breakdown 1 - Codec DAI and PCM configuration ----------------------------------- -Each codec driver must have a struct snd_soc_codec_dai to define it's DAI and -PCM's capabilities and operations. This struct is exported so that it can be +Each codec driver must have a struct snd_soc_codec_dai to define its DAI and +PCM capabilities and operations. This struct is exported so that it can be registered with the core by your machine driver. e.g. @@ -67,18 +67,18 @@ EXPORT_SYMBOL_GPL(wm8731_dai); 2 - Codec control IO -------------------- -The codec can usually be controlled via an I2C or SPI style interface (AC97 -combines control with data in the DAI). The codec drivers will have to provide -functions to read and write the codec registers along with supplying a register -cache:- +The codec can usually be controlled via an I2C or SPI style interface +(AC97 combines control with data in the DAI). The codec drivers provide +functions to read and write the codec registers along with supplying a +register cache:- /* IO control data and register cache */ - void *control_data; /* codec control (i2c/3wire) data */ - void *reg_cache; + void *control_data; /* codec control (i2c/3wire) data */ + void *reg_cache; -Codec read/write should do any data formatting and call the hardware read write -below to perform the IO. These functions are called by the core and alsa when -performing DAPM or changing the mixer:- +Codec read/write should do any data formatting and call the hardware +read write below to perform the IO. These functions are called by the +core and ALSA when performing DAPM or changing the mixer:- unsigned int (*read)(struct snd_soc_codec *, unsigned int); int (*write)(struct snd_soc_codec *, unsigned int, unsigned int); @@ -131,7 +131,7 @@ Defines a stereo enumerated control 4 - Codec Audio Operations -------------------------- -The codec driver also supports the following alsa operations:- +The codec driver also supports the following ALSA operations:- /* SoC audio ops */ struct snd_soc_ops { @@ -142,15 +142,15 @@ struct snd_soc_ops { int (*prepare)(struct snd_pcm_substream *); }; -Please refer to the alsa driver PCM documentation for details. +Please refer to the ALSA driver PCM documentation for details. http://www.alsa-project.org/~iwai/writing-an-alsa-driver/c436.htm 5 - DAPM description. --------------------- -The Dynamic Audio Power Management description describes the codec's power -components, their relationships and registers to the ASoC core. Please read -dapm.txt for details of building the description. +The Dynamic Audio Power Management description describes the codec power +components and their relationships and registers to the ASoC core. +Please read dapm.txt for details of building the description. Please also see the examples in other codec drivers. @@ -158,8 +158,8 @@ Please also see the examples in other codec drivers. 6 - DAPM event handler ---------------------- This function is a callback that handles codec domain PM calls and system -domain PM calls (e.g. suspend and resume). It's used to put the codec to sleep -when not in use. +domain PM calls (e.g. suspend and resume). It is used to put the codec +to sleep when not in use. Power states:- @@ -175,13 +175,14 @@ Power states:- SNDRV_CTL_POWER_D3cold: /* Everything Off, without power */ -7 - Codec DAC digital mute control. ------------------------------------- -Most codecs have a digital mute before the DAC's that can be used to minimise -any system noise. The mute stops any digital data from entering the DAC. +7 - Codec DAC digital mute control +---------------------------------- +Most codecs have a digital mute before the DACs that can be used to +minimise any system noise. The mute stops any digital data from +entering the DAC. -A callback can be created that is called by the core for each codec DAI when the -mute is applied or freed. +A callback can be created that is called by the core for each codec DAI +when the mute is applied or freed. i.e. |