[alsa-devel] channel swapping issue on OMAP3/TWL4030 is back

Peter Meerwald pmeerw at pmeerw.net
Fri Mar 22 13:49:37 CET 2013

> >> I'm running Linux 3.7 on a beagle-xm and observe very reproducible stereo 
> >> channel swapping issue on playback of a stereo stream (one channel has a 
> >> sine, the other is zero); the channel swap occurs on starting the playback
> > 
> >> it appears that the swapping issue is back, probably due to the DMA rework 
> >> in recent kernel?
> > 
> > kernel 3.4 does not have the issue
> Well, then, I guess, you'll have to bisect it down.

here it is:
946cc36ae550ea52adee0f42ac5034a34b5393be is the first bad commit
commit 946cc36ae550ea52adee0f42ac5034a34b5393be
Author: Peter Ujfalusi <peter.ujfalusi at ti.com>
Date:   Fri Sep 14 15:05:58 2012 +0300

    ASoC: omap-pcm: Convert to use dmaengine
    Original author: Russell King <rmk+kernel at arm.linux.org.uk>
    Switch the omap-pcm to use dmaengine.
    Certain features are not supported by after dmaengine conversion:
    1. No period wakeup mode
       DMA engine has no way to communicate this information through
       standard channels.
    Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
    Tested-by: Janusz Krzysztofik <jkrzyszt at tis.icnet.pl>
    Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>


Peter Meerwald
+43-664-2444418 (mobile)

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