[alsa-devel] Noise on right channel of WM9715

Andreas Zeiler zeiler at fs-net.de
Tue Feb 11 09:03:17 CET 2014


we have a board with an iMX6 processor from freescale and a Wolfson WM9715.
I can play music/sound files with it. We're on Linux 3.0.35.
The problem is that there is a noise on the right channel and this noise changes with the frequency. I don't mean the sample rate with that.
I'm playing a wav-file with a Sinus from 440Hz to 880Hz or higher. I can hear how the noise is changing.
Then I played a silence file with nothing in it. When I see this file it has some small artefacts (in audacity). On the left channel I hear nothing as expected.
On the right channel I hear some clicking. It's not periodic but I hear it very often.

So I turned off everything I don't need in the WM9715. So just the DAC (PCM (Register 0x18)) and the Headphone Mixer (register 0x04) are turned on. Everything else is in default state or muted. AC97 communication is working. I have a good clock etc.
I think that there is something wrong when my audio data gets into the ac97 slot. Maybe it gets shifted wrong or something else.

Can someone help me with this? Does someone know what can be wrong here??

Mit freundlichen Grüßen / With kind regards

Andreas Zeiler
(zeiler at fs-net.de<mailto:zeiler at fs-net.de>)

armStone: Pico-ITX ARM based Single Board Computer
F&S Elektronik Systeme GmbH, Stuttgart, Germany
Geschaeftsfuehrer: Holger Froelich, Guenther Scholz
Handelsregister Stuttgart HRB 18493, VAT DE178964418

More information about the Alsa-devel mailing list