[alsa-devel] snd-soc-pxa-ssp I2C/FIFO issues

Liam Girdwood lrg at kernel.org
Mon Mar 9 16:03:06 CET 2009

On Mon, 2009-03-09 at 15:47 +0100, pHilipp Zabel wrote:
> Ok,
> I'm not sure how to handle this correctly.
> Magician needs stereo S16_LE input data from alsa, DAIFMT_DSP_A on the
> wire with a frame size of 16 bit (one frame for each channel) and thus
> 2-byte DMA transfers to the FIFO (currently called 'mono' DMA params).
> Zylonite's current code uses 32 bit frame size and 4-byte DMA
> transfers to emulate I2S (S16_LE,stereo). Network mode seems to work,
> so it could be changed to use two 16 bit slots instead with 2-byte DMA
> transfers (which would make Magician happy). But...
> Daniel's board needs very strange settings because network mode
> doesn't work, so I guess he can't use 2-byte DMA transfers. Is that
> correct?
> If we can't find a way to have all machines use the mono DMA params,
> there has to be some kind of interface to set the width of the data in
> the FIFO independently from the Alsa format. How should that interface
> look like?

Btw, what pxa processor variants are you and Daniel using ?

Iirc, PXA3x SSP is quite different in terms of "usability" compared to
to PXA2x SSP. It might be worth diverging the SSP code a little here if
your CPUs are different.


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