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

pHilipp Zabel philipp.zabel at gmail.com
Mon Mar 9 17:01:37 CET 2009

On Mon, Mar 9, 2009 at 4:03 PM, Liam Girdwood <lrg at kernel.org> wrote:
> 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.

PXA272 in my case, but I share Mark's hope of keeping it unified.


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