[alsa-devel] [PATCH 1/2] ASoC: fsl_ssi: Let it understand mono

Mark Brown broonie at opensource.wolfsonmicro.com
Tue Sep 25 14:53:59 CEST 2012

On Mon, Sep 24, 2012 at 08:50:41AM -0500, Timur Tabi wrote:
> Mark Brown wrote:
> > In I2S mono just means ignoring the right channel or duplicating the
> > left channel into the right channel at one end of the link or the other.
> > As you say the clocking always has to be for an even number of channels.

> Let me see if I understand this correctly.  In order for I2S mono to work,
> we need the following:

> 1) The I2S controller (the SSI in this case) needs to be programmed to DMA
> data from memory into the left channel only of each frame, and it needs to
> pump dummy data into the right channel.  If it automatically pumps the
> same data into the right channel, then the codec doesn't need to do
> anything.  Otherwise, we need one of these:

> 2a) The codec needs to be programmed to ignore the right channel and
> internally duplicate the left channel into both left and right analog signals.

> 2b) The board needs to be wired such that only the left analog signal gets
> routed to the speakers.


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