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

Arnaud Ferraris
2020-07-15T16:20:21Z

Hi,

Le 15/07/2020 à 16:05, Mark Brown a écrit :
> On Tue, Jul 14, 2020 at 01:50:50PM -0700, Nicolin Chen wrote:
> Anything wrong with ASRC selecting SSI1 clock for both cases? The
> driver calculates the divisors based on the given clock rate, so
> the final internal rate should be the same. If there's a problem,
> I feel that's a separate bug.

Calculations are indeed good, but then the clock selection setting in
the ASRCSR register would also use SSI1 as the input clock, which
doesn't work in our case.

>> On Tue, Jul 14, 2020 at 09:27:53PM +0100, Mark Brown wrote:
>
> If you've got two radios that both need to sync to some radio derived
> frequency it gets a bit more entertaining.

It was indeed a fun ride trying to make it work for all the use-cases we
were targetting.

>
>> Yet, in case that we need to support such an edge case, what's
>> a relatively common practice to allow system select the clock
>> source now?
>
> Honestly for anything that fun it tends to be a custom machine driver.
> A property would seem reasonable though.

I think so, does my initial implementation of the properties look
sensible to you? ("fsl,asrc-input-clock" & "fsl,asrc-output-clock")

Regards,
Arnaud