[alsa-devel] [PATCHv4 0/2] McBSP: OMAP3: Add sidetone feature

Jarkko Nikula jhnikula at gmail.com
Fri Feb 19 14:39:16 CET 2010

On Fri, 19 Feb 2010 10:34:32 +0200
Peter Ujfalusi <peter.ujfalusi at nokia.com> wrote:

> I'm not sure, but you might need to configure the taps as well to have the 
> correct sidetone.
> Also I have a recollection, that the McBSP sidetone requires DSP mode (TDM) in 
> order to operate correctly, so on Beagle you might need to set up 4 channel 
> mode. And how the channel mapping in 4 channel mode works in McBSP sidetone is 
> another matter...
It seems to work with I2S too.

I think I forgot to enable control 'McBSP2 Sidetone' when I last time
tried this set (v1 or v2). But now my null test below works and I can
hear that the level is changing when I adjust the volumes with amixer.

echo 32767 >/sys/devices/platform/omap-mcbsp.2/st_taps

arecord -f dat >/dev/null |aplay -f dat /dev/zero

amixer set -D hw:0 'McBSP2 Sidetone Channel 0' 32700
amixer set -D hw:0 'McBSP2 Sidetone Channel 0' 327
amixer set -D hw:0 'McBSP2 Sidetone Channel 0' -- -32700


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