[alsa-devel] [PATCH 2/2] ASoC: nau8810: change the target of MIC BIAS supply

[John Hsu]

On 5/4/2018 7:10 AM, Mark Brown wrote:
> On Thu, May 03, 2018 at 10:46:42AM +0800, John Hsu wrote:
>> The MICBAIS will not supply if there is only one path from MICP to
>> input boost stage. The driver fixes the issue by changing the supply
>> target to input boost stage mixer.
>
> Does the input boost stage actually use the MICBIAS supply directly?
> More usually a microphone bias would supply the microphone rather than
> anything on the chip itself.

The input boost stage has a mixer of two input sources. The normal case
is that MIC goes to input PGA, then to input boot stage. The case is
the original design of the driver. But there is another path that MIC
goes input boot stage directly. The case is less happened but has chance.
Ex. The single-end MIC goes to input boot stage. Therefore, we move
the target of MICBIAS to input boost stage which can supply power for
both cases.



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