[alsa-devel] [PATCH v2 2/2] dt: binding: sound cs42l52 driver

[Brian Austin]

On Wed, 13 Nov 2013, Tomasz Figa wrote:

>>>> +		 0x00 through 0x0F.
>>>> +		 Frequency = (64xFs)/(N+2)
>>>
>>> I suppose N means the value of chgfreq property here, but this should be
>>> clearly stated. Same for Fs - I suppose it is sampling frequency, but
>>> is it default, minimum, maximum or maybe something else?
>>>
>> Frequency = (64xFs)/(N+2)
>> N = chgfreq value
>> Fs = sample rate
>
> As I mentioned in second part of my comment, is it default, minimum,
> maximum or what kind of sample rate? Or is the sample rate fixed?
>
ah! Sorry, the rate is fixed for the stream. So it varies for what rate is 
being used.


>>
>>
>>> Personally I don't like this kind of raw values being passed using Device
>>> Tree, but this one can't be really represented reasonably in a generic
>>> way (such as in Hz units) without too much effort to calculate original
>>> value in the driver, then it's fine.
>>>
>>>> +  - mica-cfg   : MIC A single-ended or differential select.
>>>> +		 0x00 = Single-Ended
>>>> +		 0x01 = Differential
>>>
>>> I'd rather make it boolean and call it cirrus,mic-a-differential.
>>>
>>>> +  - micb-cfg   : MIC B single-ended or differential select.
>>>> +		 0x00 = Single-Ended
>>>> +		 0x01 = Differential
>>>
>>> Ditto.
>>>
>>
>> I can do that as well. Thanks
>>
>>>> +  - mica-sel   : MIC A single ended input select.  For Single-Ended
>>>> +		 configuration, select which MIC to use.
>>>> +		 0x00 = MIC1
>>>> +		 0x01 = MIC2
>>>> +  - micb-sel   : MIC B single ended input select.  For Single-Ended
>>>> +		 configuration, select which MIC to use.
>>>> +		 0x00 = MIC1
>>>> +		 0x01 = MIC2
>>>
>>> Could you explain what are MIC A, MIC B, MIC1 and MIC2?
>>>
>> I can add a little more but it is best explained in the datasheet. I can
>> add a little more explaination and reference the datasheet section. I feel
>> this file might be the wrong place to go into too much depth of the pieces
>> of the device when the datasheet could be referenced. Would a reference be
>> OK?
>>
>
> I meant just explaining to me, for the purpose of this review. However it
> seems like the datasheet is publicly available, so let me just check this
> there.
>
Sorry about that.

The CS42L52 has multiple input selections for microphones. Single-ended 
and differential inputs are allowed for both Left Channel (MICA) and Right 
Channel (MICB). The +- pins can be used for stereo or mono mics.

>>>> +Example:
>>>> +
>>>> +codec: cs42l52 at 4a {
>>>
>>> coding style: Node name should be generic, i.e. codec at 4a.
>>
>> I can change this as well.  While we are talking about coding style, is
>> there a new format document somewhere with the style that was agreed to at
>> the conference just recently?
>
> I believe that the latest document is in the works, but as for style
> guidelines, most of recommendations are to be taken from ePAPR[1].
>
> [1] https://www.power.org/wp-content/uploads/2012/06/Power_ePAPR_APPROVED_v1.1.pdf
>
Thank you very much. I will take a look at this now.

Thanks again,
Brian