[alsa-devel] [PATCH] [v2] ASoC: support all possible sample rates in the WM8776 driver

Lars-Peter Clausen lars at metafoo.de
Fri Sep 16 18:27:14 CEST 2011

On 09/16/2011 05:47 PM, Timur Tabi wrote:
> Takashi Iwai wrote:
>> It's not optimal from some aspects.  Basically this should be resolved
>> in hw_constraints, not in hw_params, so that the configurator can find
>> the possible rates.  Otherwise you have no idea what rate would be
>> accepted.
> Yes, I was concerned about that.  So should I be calling one of the
> snd_pcm_hw_constraint_xxx functions in the codec's .startup function?  That
> would require ASoC to call the machine driver's .startup function *before*
> calling the codec driver's .startup function, since the machine driver's
> .startup function is where I call the codec to tell it what the mclk frequency is.

You mentioned in an earlyer mail that you can switch the sysclk rate at
runtime. So setting the constraints based on the current sysclk rate won't
really work. I think you need some mechanism to specify the supported rates on
a per machine driver basis.

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