[alsa-devel] Channel swapping issue on TI OMAP3/TWL4030

[Peter Ujfalusi]

On 02/15/11 18:23, ext ylin at mail.com wrote:
> 
>> I forgot to ask:
>> what mode you are using the McBSP?
>> Is it in element, or threshold mode?
>> You can check/change the McBSP mode in:
>> /sys/devices/platform/omap-mcbsp.2/dma_op_mode
> 
> It is in threshold mode, with max threshold 1023.  I will try other 
> modes.

This sounds safe, give the fact that the McBSP2 FIFO is 1280 word long.
The McBSP FIFO configuration has been corrected in newer kernels.

One thing that I would try is to synchronize the McBSP2 FIFO
configuration with the period size you use:
48KHz/stereo/16bit 10ms = 480 samples,
so configure the McBSP2 FIFO to 960 (for both tx, and rx threshold).
Might not help, but it worth a try...

>>> For playing, the left and right are the same data, we could not 
> tell if
>>> the channel switch happens to playback as well.
>>
>> I see. Is there a way for you to run your application to capture only,
>> and from a separate app (aplay?) play a sample, which has audio only 
> on
>> one channel?
> 
> I can fill zero to one of the play channel in our app to test it.

Great.
Let's see, if the swap also happens in the playback path as well.

-- 
Péter