[alsa-devel] [PATCH 6/6] ASoC: TWL4030: Add analog loopback support

Mark Brown broonie at sirena.org.uk
Tue Jan 27 15:41:18 CET 2009

On Tue, Jan 27, 2009 at 04:28:35PM +0200, Peter Ujfalusi wrote:
> On Tuesday 27 January 2009 16:03:16 ext Mark Brown wrote:

> > This one should be dealable with in-kernel without any work by
> > applications - WM8350 does a similar dance (for different reasons),
> > providing a shadow volume control while some of the amplifiers are
> > powered off.

> I'm going to check the code. But I think the driver still needs to keep on 
> track of the bypass switch states in order to do the right thing.

I'd expet so - the main win would be to avoid having to have user space
manually twiddle additional controls.

> > I suspect the increased power consumption here is due to the PLL being
> > required to clock the DAC properly.  Or you've transposed the figures :)

> I have checked it several times, the numbers are correct. Probably the DAC 
> clocking, but how it is working without the PLL on - because the bypass was 
> working...

I'd imagine that it did actually have a clock (probably whatever clock
would be input to the PLL), just not at the optimal rate.

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