[alsa-devel] [PATCH] ASoC: adau1701: Reset codec based on sample rate changes

[Lars-Peter Clausen]

On 03/23/2016 01:48 PM, Mark Brown wrote:
> On Wed, Mar 23, 2016 at 12:58:23PM +0100, pascal.huerst at gmail.com wrote:
> 
>> Instead of checking if mclk/lrclk ratio has changed, check if
>> sample rate has changed. In certain cases, the mclk might be
>> changed in the machine driver, which can lead to the same
>> mclk/lrclk ration, eventhow the sample rate has changed.
> 
>> Since the codec has to be programmed differently for every
>> sample rate, its better to check for samplerate changes instead
>> of mclk/lrclk ration changes.
> 
> Why does this mean we have to reset the CODEC rather than just
> reprogramming it?

Quoting from the datasheet:

	The clock mode should not be changed without also resetting
	the ADAU1701. If the mode is changed during operation, a
	click or pop can result in the output signals. The state of the
	PLL_MODEx pins should be changed while RESET is held low.

- Lars

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