[alsa-devel] [PATCH 3/5] ASoC: Docs: update DAPM
liam.r.girdwood at linux.intel.com
Mon Sep 23 13:14:00 CEST 2013
Update the DAPM documentation and bring it up to date with the current
code base. This includes API changes and new widgets.
Signed-off-by: Liam Girdwood <liam.r.girdwood at linux.intel.com>
Documentation/sound/alsa/soc/dapm.txt | 71 ++++++++++++++++++++---------------
1 file changed, 41 insertions(+), 30 deletions(-)
diff --git a/Documentation/sound/alsa/soc/dapm.txt b/Documentation/sound/alsa/soc/dapm.txt
index 05bf5a0..7dfd88c 100644
@@ -21,7 +21,7 @@ level power systems.
There are 4 power domains within DAPM
- 1. Codec domain - VREF, VMID (core codec and audio power)
+ 1. Codec bias 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.
@@ -63,14 +63,22 @@ 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 componnents.
+ 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 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.
+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.
Most widgets have a name, register, shift and invert. Some widgets have extra
parameters for stream name and kcontrols.
@@ -80,11 +88,13 @@ parameters for stream name and kcontrols.
Stream Widgets relate to the stream power domain and only consist of ADCs
-(analog to digital converters) and DACs (digital to analog converters).
+(analog to digital converters), DACs (digital to analog converters),
+AIF IN and AIF OUT.
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
@@ -94,6 +104,11 @@ 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
@@ -121,12 +136,14 @@ 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 Platform/Machine domain Widgets
+2.3 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) that can be independently powered. e.g.
+machine audio component (non codec or DSP) that can be independently
o Speaker Amp
o Microphone Bias
@@ -146,12 +163,12 @@ 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 Domain
+2.4 Codec (BIAS) Domain
-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.
+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.
2.5 Virtual Widgets
@@ -169,15 +186,16 @@ 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 Widget Interconnections
+3. Codec/DSP Widget Interconnections
-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.
+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.
-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.
+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
e.g., from the WM8731 output mixer (wm8731.c)
@@ -247,16 +265,9 @@ machine and includes the codec. e.g.
o Mic Jack
o Codec Pins
-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.
+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.
5 DAPM Widget Events
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