[alsa-devel] WM8994 playback delay

Sangbeom Kim sbkim73 at samsung.com
Thu Mar 29 01:02:29 CEST 2012

Hi, Mark,

Currently, We are developing SMDK with Exynos5250 and  WM8994 on 3.3-rc6.
We try to enable CONFIG_PM_RUNTIME and on/off control of power domain.
But It has playback delay in the first playback.(3~4sec and 6/10times)

In that time, Log maessage is 
'wm8994-codec wm8994-codec: Timed out waiting for DC Servo 300'
wait_for_dc_servo() function generate above message on sound/soc/codecs/wm_hubs.c

After removing wait_for_dc_servo for testing, playback delay is disappeared.
So, Could you please explain the  purporse of wait_for_dc_servo()?
If wait_for_dc_servo() is removed, What kind of problem can be happened?


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