[PATCH] ASoC: Put LM4853 under DAPM control on GTA02

Andy Green andy at openmoko.com
Tue Mar 3 12:08:35 CET 2009

Hash: SHA1

Somebody in the thread at some point said:
| Control for the power for the LM4853 on the GTA02 had been made directly
| visible to user space, needlessly burning power when no output was being
| produced and causing pops and clicks to be worsened due to a lack of
| integration with the power sequencing done by DAPM.
| Bring the amplifier power under DAPM control, saving power and reducing
| the levels of pops and clicks caused.
| The existing control is left in place for the benefit of scenario files
| but now has no effect.

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.

It's mostly OK to assume that for that amp when doing the ringer action
for example, but the amp also drives the headset, which can be active
with no PCM footprint.  Is it OK?

- -Andy
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