[alsa-devel] [PATCH] ASoC: tpa6130a2: Support for limiting gain

Liam Girdwood lrg at slimlogic.co.uk
Thu May 6 16:03:53 CEST 2010

On Thu, 2010-05-06 at 14:21 +0300, Peter Ujfalusi wrote:
> On Thursday 06 May 2010 12:49:42 ext Mark Brown wrote:
> > On Thu, May 06, 2010 at 10:37:18AM +0300, Peter Ujfalusi wrote:
> > > Add support for platform dependent gain limiting on the
> > > tpa6130a2 (and tpa6140a2) Headset amplifier.
> > > 
> > > Signed-off-by: Peter Ujfalusi <peter.ujfalusi at nokia.com>
> > 
> > Acked-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
> Thanks,
> > but we should really provide a generic implementation of this.
> Yeah, would be really useful.
> What I was wondering about is the cases when you have a codec + amp in a 
> system..
> If we take for example twl4030 and the tpa6130 connected together:
> than we have 4 levels of gain control inside of twl, than one additional level 
> on the tpa side.
> What would be nice is to somehow limit the whole chain, but it seams really 
> complicated thing because of the big amount of combinations that you can 
> actually achieve the same level at the output.
> So the gain-chain limitation is really holistic problem IMHO.
> But I guess the core could gain support for limiting individual volume controls.
> Some soc-limit-gain("kcontrol name", min, max)
> Than it goes through the controls on the card, finds the kcontrol, and fixers up 
> the limits..
> So machine drivers can fix up the gain limits on their cards with ease, and no 
> additional support from the codec/amp drivers are going to be needed
> Hmm, this would be neat!
> Sounds  interesting, I might look at this ;)

Applied. We can always update this when core has this feature.



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