[alsa-devel] Set eapd to follow stream on or off
tiwai at suse.de
Tue May 20 11:03:33 CEST 2014
At Tue, 20 May 2014 16:52:43 +0800,
> > At Tue, 20 May 2014 15:15:49 +0800,
> > Kailang wrote:
> >> Hi Takashi,
> >> HP machine had pop noise via speaker.
> >> If EAPD on or off, speaker will have pop noise.
> >> So, they want to set eapd to follow with stream on or off.
> > I can apply this as is, but still I wonder whether this results in
> > other problems. Doing EAPD on/off there means that it happens far
> > more often. For example, what happens if you do like below?
> > while true; do
> > echo -n > /dev/snd/pcmC0D0p
> > done
> > And, what if the device is resumed from power-saving by an audio
> > playback? Immediately after the power up, it'll start the streaming,
> > so it'll turn on EAPD.
> > That said, isn't it just a need for some delay before EAPD on/off?
> No, eapd on or off will cause pop noise.
Does it do always?
> Our customer just want to do eapd on when stream is open.
> The pop noise will not clear. Because music gain was biger than pop noise.
Opening a stream doesn't mean that it follows the loud sound
immediately. The script above wouldn't produce any sound but just
does open/close the stream. Did you try that?
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