RobertCNelson/linux-dev — Issue #2: beaglebone usb audio noise
Author: ferryzhou
Created: 2012-02-24 21:41:27+00:00
State: open

iMic is used for beaglebone audio

I installed ubuntu 11.10 r5 on the beaglebone, further installed alsa-utils and run alsamixer to adjust the volume.

line in and line out is connected to iMic.

Here is the problem: if I run the command

arecord | aplay

I can hear the noise (sometimes when system is a little bit busy, say if another ssh remote connected to beaglebone and run top command, anytime the statistics is updated, a noise is shown up).

This problem doesn't happen on beagleboard.

After check with top command. I found the difference is: in beaglebone, if I run aplay a.wav or arecord | alay, a busy kworker is shown up, this kworker consumes more than 90% CPU. In beagleboard, no busy kworker is shown up when aplay is running.