[alsa-devel] Question: PCM short and long sync formats

Omair Mohammed Abdullah omair.m.abdullah at linux.intel.com
Mon Mar 26 11:06:53 CEST 2012

On Wednesday 21 March 2012 05:21 PM, Mark Brown wrote:
> On Wed, Mar 21, 2012 at 03:51:36PM +0530, Omair Mohammed Abdullah wrote:
>> I was looking for PCM short frame sync and PCM long frame sync, but
>> they are not present in soc-dai.h (FORMAT_MASK). Is there a way to
>> derive them from other formats or should I just add them?
> What do you mean when you say "PCM short frame sync" and "PCM long
> frame sync"?

Sorry for the late reply, I was away.

What I mean by short/long frame sync is: the frame sync lasts for 1 
bit/1 word wide.

Eg.: For short frame sync, we get a frame sync signal for 1 clock before 
the first bit on the RX/TX.

It is different from I2S mode where the frame sync is inverted and the 
transition starts 1 clock before the bits and lasts till bit 1.

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