Re: [PATCH 0/4] ASoC: fsl_asrc: allow selecting arbitrary clocks

[Arnaud Ferraris]

Le 16/07/2020 à 14:18, Mark Brown a écrit :
> On Wed, Jul 15, 2020 at 02:03:08PM -0700, Nicolin Chen wrote:
>> On Wed, Jul 15, 2020 at 03:05:19PM +0100, Mark Brown wrote:
>>> On Tue, Jul 14, 2020 at 01:50:50PM -0700, Nicolin Chen wrote:
> 
>>>> Thanks for the input. Fox i.MX6, I don't feel it would be that
>>>> drastically different though. And both SSI1 and SSI2 can simply
>>>> select the same root clock source to avoid that happen.
> 
>>> If you've got two radios that both need to sync to some radio derived
>>> frequency it gets a bit more entertaining.
> 
>> I'm simply curious what could be a problem. Do you mind educating
>> me a bit? And ASRC here isn't a radio but a sample rate converter
>> working as a BE in DPCM setup, using radio-capture for example...
> 
> My understanding was that this application was using the ASRC to convert
> between the sample rates of two different radios - the rates may be
> nominaly the same but in practice different so the audio will glitch
> after a while when the clocks drift far enough apart.

That's part of the issues we had to solve, yes. The other part is more
traditional sample rate conversion on an as-needed basis, as we can't
assume which rate will be used (iPhone's use 16kHz, Android phones stick
to 8kHz, and headsets can use both depending on their capabilities).