linux/Documentation/devicetree/bindings/sound/dmic.txt
Jenny TC bc0a7dbc5a
ASoC: dmic: introduce mode switch delay
On startup, applications such as PulseAudio or CRAS enable playback or
capture on all PCM devices to verify that configurations are correct,
and close them immediately. For DMICs, this can result in the clock
being turned off very quickly, which may not compatible with internal
state machine transition requirements.

This patch add a mode-switch delay which will prevent the clock from
being turned off without complying with manufacturer timing
specifications. While the DMIC clock may be controlled at a lower level,
be it with hardware or firmware, applying the delay during the
STOP_TRIGGER phase ensures that there is no race condition, e.g. with
the hardware/firmware turning off the clock earlier

Signed-off-by: Sathyanarayana Nujella <sathyanarayana.nujella@intel.com>
Signed-off-by: Jairaj Arava <jairaj.arava@intel.com>
Signed-off-by: Harsha Priya <harshapriya.n@intel.com>
Signed-off-by: Jenny TC <jenny.tc@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
2018-11-28 15:19:31 +00:00

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Device-Tree bindings for Digital microphone (DMIC) codec
This device support generic PDM digital microphone.
Required properties:
- compatible: should be "dmic-codec".
Optional properties:
- dmicen-gpios: GPIO specifier for dmic to control start and stop
- num-channels: Number of microphones on this DAI
- wakeup-delay-ms: Delay (in ms) after enabling the DMIC
- modeswitch-delay-ms: Delay (in ms) to complete DMIC mode switch
Example node:
dmic_codec: dmic@0 {
compatible = "dmic-codec";
dmicen-gpios = <&gpio4 3 GPIO_ACTIVE_HIGH>;
num-channels = <1>;
wakeup-delay-ms <50>;
modeswitch-delay-ms <35>;
};