[alsa-devel] [PATCH v2] ASoC: tlv320dac33: Power down digital parts, when not needed

Liam Girdwood lrg at slimlogic.co.uk
Fri Dec 10 23:51:03 CET 2010

On Fri, 2010-12-10 at 13:26 +0200, Peter Ujfalusi wrote:
> If the following scenario has been followed:
> 1. Enable analog bypass
> amixer sset 'Analog Left Bypass' on
> amixer sset 'Analog Right Bypass' on
> 2. Start playback
> aplay -fdat -d3 /dev/zero
> After the playback stopped (3 sec), and the soc timeout (5 sec),
> the digital parts of the codec will remain powered up.
> This means that the DAI clocks are continue to run, the
> oscillator remain operational, etc.
> Use the SND_SOC_DAPM_POST_PMD widget to get notification
> about the stopped stream, and power down the digital
> part of the codec.
> If the analog bypass is enabled, than the codec will remain in
> BIAS_ON level, and things will work correctly.
> In case, if the bypass is disabled, than the codec will
> fall to BIAS_STANDBY than to BIAS_OFF level, as it used
> to.
> The digital part of DAC33 is initialized at every stream start
> (DAPM_PRE:PRE_PMU event), so subsequent streams (within 5 sec)
> will have working DAI.
> When the codec is coming out from BIAS_OFF, the full power-up
> sequence followed by the same DAPM_PRE widget event will power up
> the digital part.
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi at nokia.com>
> Acked-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
> ---



Freelance Developer, SlimLogic Ltd
ASoC and Voltage Regulator Maintainer.

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