[alsa-devel] [question] Sample rate IC followed by DAC

[Matt Flax]

On 04/11/16 22:31, Clemens Ladisch wrote:
> Matt Flax wrote:
>> I have a sample rate converter IC, which is followed by a DAC. This kind of setup :
>>
>> SoC chip -> Sample rate conv. chip -> DAC chip
> What is the purpose of the converter?  What problem does it solve?
It has a lower noise floor then libsamplerate.
>
>> How do you construct a machine driver for this setup ?
> The original DAC driver will not work correctly, as far as sample rate
> settings are concerned.
Yes, I was expecting that. Tell me, even in the current ALSA version, is 
there any support for sample rate converter hardware chains ? Situations 
where we need to control standard codecs which a after sample rate 
converters.
>> Unfortunately the silicon only supports an older 3.14 kernel.
> You mean, you paid for _no support_?  And now are asking here instead?
> (Not that a newer kernel version would help ...)
It is the Nexell s5p6818 silicon, community only support at this point. 
Also I couldn't find any examples of sample rate converter hardware 
chains in linux/sound/soc ...
> Well, if your goal isn't a proper driver for upstream, just hack the
> existing DAC driver to access the other I²C device, when needed.
>
Sure, I can do this. I can't find any examples on operating a codec 
within a codec. Would I export all function symbols and do it that way ?
> Regards,
> Clemens