[PATCH] ASoC: Put LM4853 under DAPM control on GTA02
andy at openmoko.com
Tue Mar 3 12:31:13 CET 2009
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Somebody in the thread at some point said:
| On Tue, Mar 03, 2009 at 11:08:35AM +0000, Andy Green wrote:
|> This sounds great, but how does DAPM integrate with the analogue path
|> usage which is the way we passthru audio for normal telephony? Last
|> time I looked the ALSA side power management took a PCM-centric view of
|> the world, it believes that PCM open was the sign we needed power some
|> kind of "on" power state.
| No, that's never been the case - ASoC has always handled full power path
| management. If there is a complete path from a connected input to a
| connected output then that path will be powered up - if this weren't the
| case none of the paths in the codec would be powered for your bypass
| paths so there would be nothing for the speaker to amplify.
I'm thinking about Vref driver impedence for example, unless I am
suffering from false memory syndrome this is managed as I described,
such that we are at 500K impedence when using only analogue paths.
| The handling of the digital streams provides automatic power managment
| for the DACs and ADCs so that their paths aren't powered when they
| aren't in use.
How does the power management of the amp improve by DAPM then, just the
sequencing during suspend and resume?
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