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| -rw-r--r-- | Documentation/sound/soc/dapm.rst | 38 |
1 files changed, 36 insertions, 2 deletions
diff --git a/Documentation/sound/soc/dapm.rst b/Documentation/sound/soc/dapm.rst index 8d741295fc40..57d96a39f124 100644 --- a/Documentation/sound/soc/dapm.rst +++ b/Documentation/sound/soc/dapm.rst @@ -250,8 +250,42 @@ a virtual widget - a widget with no control bits e.g. This can be used to merge two signal paths together in software. -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(). +Registering DAPM controls +========================= + +In many cases the DAPM widgets implemented statically in a ``static const +struct snd_soc_dapm_widget`` array and the routes connecting them in a +``static const struct snd_soc_dapm_route`` array in a codec driver, and +simply declared via the ``dapm_widgets`` and ``num_dapm_widgets`` fields of +the ``struct snd_soc_component_driver`` so the driver registration will +take care of populating them:: + + static const struct snd_soc_dapm_widget wm2000_dapm_widgets[] = { + SND_SOC_DAPM_OUTPUT("SPKN"), + SND_SOC_DAPM_OUTPUT("SPKP"), + ... + }; + + /* Target, Path, Source */ + static const struct snd_soc_dapm_route wm2000_audio_map[] = { + { "SPKN", NULL, "ANC Engine" }, + { "SPKP", NULL, "ANC Engine" }, + ... + }; + + static const struct snd_soc_component_driver soc_component_dev_wm2000 = { + ... + .dapm_widgets = wm2000_dapm_widgets, + .num_dapm_widgets = ARRAY_SIZE(wm2000_dapm_widgets), + ... + }; + +In more complex cases the list of DAPM widgets and/or routes can be only +known at build time. This happens for example when a driver supports +different models having a different set of features. In those cases +separate widgets and routes arrays implementing the case-specific features +can be registered programmatically by calling snd_soc_dapm_new_controls() +and snd_soc_dapm_add_routes(). Codec/DSP Widget Interconnections |