diff options
Diffstat (limited to 'Documentation/sound/alsa/soc/dapm.txt')
| -rw-r--r-- | Documentation/sound/alsa/soc/dapm.txt | 73 |
1 files changed, 31 insertions, 42 deletions
diff --git a/Documentation/sound/alsa/soc/dapm.txt b/Documentation/sound/alsa/soc/dapm.txt index 6faab48..05bf5a0 100644 --- a/Documentation/sound/alsa/soc/dapm.txt +++ b/Documentation/sound/alsa/soc/dapm.txt @@ -21,7 +21,7 @@ level power systems. There are 4 power domains within DAPM - 1. Codec bias domain - VREF, VMID (core codec and audio power) + 1. Codec domain - VREF, VMID (core codec and audio power) Usually controlled at codec probe/remove and suspend/resume, although can be set at stream time if power is not needed for sidetone, etc. @@ -30,7 +30,7 @@ There are 4 power domains within DAPM machine driver and responds to asynchronous events e.g when HP are inserted - 3. Path domain - audio subsystem signal paths + 3. Path domain - audio susbsystem signal paths Automatically set when mixer and mux settings are changed by the user. e.g. alsamixer, amixer. @@ -63,22 +63,14 @@ Audio DAPM widgets fall into a number of types:- o Line - Line Input/Output (and optional Jack) o Speaker - Speaker o Supply - Power or clock supply widget used by other widgets. - o Regulator - External regulator that supplies power to audio components. - o Clock - External clock that supplies clock to audio components. - o AIF IN - Audio Interface Input (with TDM slot mask). - o AIF OUT - Audio Interface Output (with TDM slot mask). - o Siggen - Signal Generator. - o DAI IN - Digital Audio Interface Input. - o DAI OUT - Digital Audio Interface Output. - o DAI Link - DAI Link between two DAI structures */ o Pre - Special PRE widget (exec before all others) o Post - Special POST widget (exec after all others) (Widgets are defined in include/sound/soc-dapm.h) -Widgets can be added to the sound card by any of the component driver types. -There are convenience macros defined in soc-dapm.h that can be used to quickly -build a list of widgets of the codecs and machines DAPM widgets. +Widgets are usually added in the codec driver and the machine driver. There are +convenience macros defined in soc-dapm.h that can be used to quickly build a +list of widgets of the codecs and machines DAPM widgets. Most widgets have a name, register, shift and invert. Some widgets have extra parameters for stream name and kcontrols. @@ -88,13 +80,11 @@ parameters for stream name and kcontrols. ------------------------- Stream Widgets relate to the stream power domain and only consist of ADCs -(analog to digital converters), DACs (digital to analog converters), -AIF IN and AIF OUT. +(analog to digital converters) and DACs (digital to analog converters). Stream widgets have the following format:- SND_SOC_DAPM_DAC(name, stream name, reg, shift, invert), -SND_SOC_DAPM_AIF_IN(name, stream, slot, reg, shift, invert) NOTE: the stream name must match the corresponding stream name in your codec snd_soc_codec_dai. @@ -104,11 +94,6 @@ e.g. stream widgets for HiFi playback and capture SND_SOC_DAPM_DAC("HiFi DAC", "HiFi Playback", REG, 3, 1), SND_SOC_DAPM_ADC("HiFi ADC", "HiFi Capture", REG, 2, 1), -e.g. stream widgets for AIF - -SND_SOC_DAPM_AIF_IN("AIF1RX", "AIF1 Playback", 0, SND_SOC_NOPM, 0, 0), -SND_SOC_DAPM_AIF_OUT("AIF1TX", "AIF1 Capture", 0, SND_SOC_NOPM, 0, 0), - 2.2 Path Domain Widgets ----------------------- @@ -136,14 +121,12 @@ If you dont want the mixer elements prefixed with the name of the mixer widget, you can use SND_SOC_DAPM_MIXER_NAMED_CTL instead. the parameters are the same as for SND_SOC_DAPM_MIXER. - -2.3 Machine domain Widgets --------------------------- +2.3 Platform/Machine domain Widgets +----------------------------------- Machine widgets are different from codec widgets in that they don't have a codec register bit associated with them. A machine widget is assigned to each -machine audio component (non codec or DSP) that can be independently -powered. e.g. +machine audio component (non codec) that can be independently powered. e.g. o Speaker Amp o Microphone Bias @@ -163,12 +146,12 @@ static int spitz_mic_bias(struct snd_soc_dapm_widget* w, int event) SND_SOC_DAPM_MIC("Mic Jack", spitz_mic_bias), -2.4 Codec (BIAS) Domain ------------------------ +2.4 Codec Domain +---------------- -The codec bias power domain has no widgets and is handled by the codecs DAPM -event handler. This handler is called when the codec powerstate is changed wrt -to any stream event or by kernel PM events. +The codec power domain has no widgets and is handled by the codecs DAPM event +handler. This handler is called when the codec powerstate is changed wrt to any +stream event or by kernel PM events. 2.5 Virtual Widgets @@ -186,16 +169,15 @@ After all the widgets have been defined, they can then be added to the DAPM subsystem individually with a call to snd_soc_dapm_new_control(). -3. Codec/DSP Widget Interconnections -==================================== +3. Codec Widget Interconnections +================================ -Widgets are connected to each other within the codec, platform and machine by -audio paths (called interconnections). Each interconnection must be defined in -order to create a map of all audio paths between widgets. +Widgets are connected to each other within the codec and machine by audio paths +(called interconnections). Each interconnection must be defined in order to +create a map of all audio paths between widgets. -This is easiest with a diagram of the codec or DSP (and schematic of the machine -audio system), as it requires joining widgets together via their audio signal -paths. +This is easiest with a diagram of the codec (and schematic of the machine audio +system), as it requires joining widgets together via their audio signal paths. e.g., from the WM8731 output mixer (wm8731.c) @@ -265,9 +247,16 @@ machine and includes the codec. e.g. o Mic Jack o Codec Pins -Endpoints are added to the DAPM graph so that their usage can be determined in -order to save power. e.g. NC codecs pins will be switched OFF, unconnected -jacks can also be switched OFF. +When a codec pin is NC it can be marked as not used with a call to + +snd_soc_dapm_set_endpoint(codec, "Widget Name", 0); + +The last argument is 0 for inactive and 1 for active. This way the pin and its +input widget will never be powered up and consume power. + +This also applies to machine widgets. e.g. if a headphone is connected to a +jack then the jack can be marked active. If the headphone is removed, then +the headphone jack can be marked inactive. 5 DAPM Widget Events |