[alsa-devel] ASOC: For SND_SOC_DAIFMT_IB_IF what is invert baseed on?

Liam Girdwood lrg at slimlogic.co.uk
Mon Oct 27 14:47:27 CET 2008

On Mon, 2008-10-27 at 21:24 +0800, Richard Zhao wrote:
> > Not quite, the clock is simply inverted compared to it's normal level.
> >
> Well, what's the normal level? i2s LRCLK 's normal level is low for
> frame start, but pcm's normal level is high for frame start.
> Different chips may have different meaning of "invert", because
> "normal level" is not well defined. 

normal == standard. 

I2S spec is here :-


and is well defined.

> SND_SOC_DAIFMT_NB_NF is a common
> macro, so it cannot depend on any chip.  So, could you please explain
> in details what normal level and invert level of LRCLK/BCLK are in
> i2s, pcm, left/right justified?

The wm8750 datasheet shows all this in diagrams :-


It might be easier if you would send in your code so we can see what you
are trying to accomplish. 


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