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Diffstat (limited to 'Documentation/sound/soc/dapm.rst')
| -rw-r--r-- | Documentation/sound/soc/dapm.rst | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/Documentation/sound/soc/dapm.rst b/Documentation/sound/soc/dapm.rst index eb50400fa321..8d741295fc40 100644 --- a/Documentation/sound/soc/dapm.rst +++ b/Documentation/sound/soc/dapm.rst @@ -16,9 +16,27 @@ recompiling are required for user space applications. DAPM makes power switching decisions based upon any audio stream (capture/playback) activity and audio mixer settings within the device. -DAPM spans the whole machine. It covers power control within the entire -audio subsystem, this includes internal codec power blocks and machine -level power systems. +DAPM is based on two basic elements, called widgets and routes: + + * a **widget** is every part of the audio hardware that can be enabled by + software when in use and disabled to save power when not in use + * a **route** is an interconnection between widgets that exists when sound + can flow from one widget to the other + +All DAPM power switching decisions are made automatically by consulting an +audio routing graph. This graph is specific to each sound card and spans +the whole sound card, so some DAPM routes connect two widgets belonging to +different components (e.g. the LINE OUT pin of a CODEC and the input pin of +an amplifier). + +The graph for the STM32MP1-DK1 sound card is shown in picture: + +.. kernel-figure:: dapm-graph.svg + :alt: Example DAPM graph + :align: center + +DAPM power domains +================== There are 4 power domains within DAPM: @@ -47,12 +65,6 @@ Stream domain Enabled and disabled when stream playback/capture is started and stopped respectively. e.g. aplay, arecord. -All DAPM power switching decisions are made automatically by consulting an audio -routing graph of the whole machine. This graph is specific to each machine and -consists of the interconnections between every audio component (including -internal codec components). All audio components that affect power are called -widgets hereafter. - DAPM Widgets ============ |