[alsa-devel] 100.0% power usage of Device Audio codec (HDA) on wake

[Takashi Iwai]

At Tue, 20 Nov 2012 09:56:19 +0100,
David Henningsson wrote:
> 
> On 11/20/2012 09:32 AM, Takashi Iwai wrote:
> > At Tue, 20 Nov 2012 09:07:21 +0100,
> > David Henningsson wrote:
> >>
> >> It does put another question - from where does powertop get its values,
> >> and do we have to do anything on our side to make sure / aid them being
> >> correct?
> >
> > powertop checks /sys/class/sound/hwC*D*/power_{off|on}_acct files.
> > They contain the time (in ms) how long the codec is in the power-save
> > mode.
> 
> Thanks. But I have also recently seen a computer where powertop showed a 
> Watt number, essentially saying that the codec consumed 1.4 Watts or so 
> (I don't remember the exact number). Have you seen that too?

When 1.4W is constantly consumed even without PCM, it's a bit too
high.  But with PCM playback, about 1W usage can be measured normally,
I guess.


Takashi