Subject: [alsa-devel] [PATCH 1/1] ASoC: sgtl5000: enable VAG_POWER for LINE_IN

From: [email-masked] (Dong Aisheng)
Date: Wed, 1 Aug 2012 10:46:33 +0800

On Sat, Jul 28, 2012 at 10:39:59PM +0800, Shawn Guo wrote:
> On Fri, Jul 27, 2012 at 07:18:42PM +0800, Dong Aisheng wrote:
> > From: Dong Aisheng <[email-masked]>
> > 
> > LINE_IN also needs VAG_POWER on or we may hear noise when directly
> > route LINE_IN to Headphone Mux.
> 
> The following is what I see from sgtl5000 data sheet about VAG_POWER.
> 
>   VAG is the internal voltage reference for the ADC and DAC.
> 
> Are you seeing any info that requires VAG_POWER in route of LINE_IN to
> Headphone Mux?  Or it's only a result from your testing?
> 
No, it's from the test result.
Maybe i should have added a FIXME for this.

> Does it also fix the noise issue you mentioned with normal recording
> (LINE_IN to ADC) before?
> 
ADC also needs VAG power which already fixed by:
commit f0cdcf3 (ASoC: sgtl5000: Enable VAG when DAC/ADC up)
This patch is only for direct LINE_IN to Headphone Mux.

Regards
Dong Aisheng