[alsa-devel] [Q] ASoC: What's the real meaning of SND_SOC_DAIFMT_NB_NF?

Peter Ujfalusi peter.ujfalusi at ti.com
Fri Feb 24 15:09:39 CET 2012

On 02/24/2012 01:05 PM, javier Martin wrote:
>> I don't think it is going to break. I would guess that the channels are
>> swapped on these machines at the moment. If you correct the CPU dai
>> driver the only thing that will happen is that the channels will jump in
>> their correct place.
> That would be true for stereo. However, mono should not be working right now.

The notion of mono in I2S, Left/Right Justified formats is not really
valid. They are stereo protocols by design. DSP_A/B is used with mono
audio (which often referred as PCM).
It is the responsibility of the codec/cpu drivers to interpret the
standards correctly, and configure themselves accordingly. Take a look
at the Wolfson codec documentation they are really good in this matter
(what I2S, DSP/PCM, and other coding means in real life).
You can look at the omap-mcbsp driver for an example, but configuring
the FS/BC polarity in the format selection (without taking a look at the
INV mask) does not seam to be correct.


More information about the Alsa-devel mailing list