Re: [alsa-devel] [RFC PATCH] ASoC: wm8741: Allow master clock switching

On 2015-06-05 at 05:22PM, Charles Keepax wrote:

I think rather than removing the constraints entirely here, perhaps just don't set any constraints if there is no SYSCLK yet. That way we get the benefits of the constraints for single clock systems (such as user-space being able to arrange appropriate software resampling) but those like yours can configure the clock later.

Good point, I will add it to v2.

...

• if (!wm8741->sysclk) {

• dev_err(codec->dev,
  

• 	"No MCLK configured, call set_sysclk() on hw_params\n");
  

• return -EINVAL;
  

• }

Then you can keep this error check here and fail if we reach hw_params and still don't have a SYSCLK. You will probably need to provide a way to clear the SYSCLK though set_dai_sysclk as well.

Is snd_soc_dai_set_sysclk( , , 0, ) the right way to clear the SYSCLK?

Thanks, Sergej