[alsa-devel] [PATCH 2/3] ASoC: rt5677: add a platform config option for MICBIAS voltage

[Ben Zhang]

On Fri, Dec 12, 2014 at 5:27 AM, Mark Brown <broonie at kernel.org> wrote:
> On Wed, Dec 10, 2014 at 08:15:26PM -0800, Ben Zhang wrote:
>
>> The MICBIAS voltage for IN1 can be set to 1.476V/2.970V/1.242V/2.475V
>
> The changelog says "platform config" but this is adding DT binding.
>
>> +- realtek,micbias1
>> +  Select 0/1/2/3 to set MICBIAS1 voltage to 1.476V/2.970V/1.242V/2.475V
>> +
>
> Why is this being specified as some magic number rather than using the
> voltage (or at least providing defines for the voltage) - this is going
> to do little to make the DT legible and...
>
>> +enum rt5677_micbias {
>> +     RT5677_MICBIAS_1_476V = 0,
>> +     RT5677_MICBIAS_2_970V = 1,
>> +     RT5677_MICBIAS_1_242V = 2,
>> +     RT5677_MICBIAS_2_475V = 3,
>> +};
>
> ...I see there are defined for platform data.

This patch adds both an entry to the platform data and a DT binding
for MICBIAS level selection. The 4 voltage options
(1.476V/2.970V/1.242V/2.475V) are the only ones supported by the codec
hardware, so it seems an enum is better than specifying the exact
voltage directly. I was following the two examples below:

Documentation/devicetree/bindings/sound/cs42l52.txt (cirrus,micbias-lvl)
Documentation/devicetree/bindings/sound/tlv320aic3x.txt (ai3x-micbias-vg)

I'm new to devicetree bindings. Is there something like an enum in DT?