Introduction to DAPM, Linux Power Management for Embedded Audio Devices
summary
DAPM models audio hardware as a widget/route graph and automatically powers only widgets on active routes to cut unnecessary draw while minimizing pops and clicks. Drivers declare widgets and routes (use regmap registers) and ASoC core walks the graph to power down, apply routing, then power up. Inspect with per-widget files in debugfs and trace sequences with ftrace and regmap events; visualization via dam-graph remote mode (busybox-friendly) or legacy vis-dapm. Documentation and tooling patches are proposed and submitted.
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chapters (8)
- 0:00Introduction
- 1:03ALSA and sound card evolution
- 4:39What is DAPM
- 8:16DAPM widgets details
- 12:09Implementing DAPM in driver
- 20:36Inspecting DAPM state
- 26:41Debugging DAPM with ftrace
- 29:29Q&A
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