Am Mittwoch, den 15.02.2012, 01:38 -0800 schrieb j:
> On 02/15/2012 01:31 AM, Paul Menzel wrote:
> > Am Sonntag, den 12.02.2012, 00:22 +0100 schrieb Paul Menzel:
> >> Am Freitag, den 10.02.2012, 06:08 -0800 schrieb Arjan van de Ven:
> >>> On 2/10/2012 1:07 AM, Paul Menzel wrote:
> >>>> Unfortunately neither `lsof` nor `fuser` returned any process using that
> >>>> device.
> >>>>
> >>>>          $ sudo lsof /dev/snd/hwC0D0
> >>>>          $ sudo fuser -v /dev/snd/hwC0D0
> >>> also look for /dev/dsp or similar
> >> That was also to no avail.
> >>
> >>>>>> or you found a real kernel driver bug ;-)
> >>>> Looks like it. I guess I will contact the ALSA list and asking what this
> >>>> device is about and if they can fix it.
> >>>>
> >>>> Could you answer a last question, please? What is PowerTOP actually
> >>>> checking to figure out the usage.
> >>> the codec's directory in sysfs (say
> >>> /sys/devices/pci0000.00/0000:00:1b.0/sound/card0/hwC0D3) has 2 files,
> >>> power_on_acct and power_off_act
> >>> these count time that the codec is on or off respectively.
> >>> powertop calculates a delta of these two over the measurement interval
> >>> (20 seconds), and then since it knows how long it was on and off,
> >>> calculates the percentage.
> >> Thank you very much for that information. I brought that problem up to
> >> the alsa-devel list [1].
> > According to Takashi Iwai this is a known missing feature nobody has yet
> > implemented. To get the power management enabled the audio device has to
> > be opened by for example `echo -n | aplay`.
> >
> > Unfortunately I do not have any numbers how much "wasted" power we are
> > talking about here.

> >> [1] 
> >> http://mailman.alsa-project.org/pipermail/alsa-devel/2012-February/049019.html
> > [2] 
> > http://mailman.alsa-project.org/pipermail/alsa-devel/2012-February/049095.html

Am Mittwoch, den 15.02.2012, 01:36 -0800 schrieb j:
> I see the same in my powertop2 results and have been searching for ways 
> to cut it down as it seems to be the only thing really that while lists 
> not actual wattage being drawn stays at a constant 100%. If there is any 
> useful info I can pass along let me know.
> 
> Thanks for all the great work on the powertop project 

> Sorry forgot to post it says its Audio codec hwC0D0: Conextant. When not 
> power saving (on ac) runs about 426mW 100% usage no results return with 
> the listed commands requested before. When I apply my battery power 
> savings nothing in mW but still stays at 100% usage

Please post the output of the `/sys/*` files I also posted.

        $
        more /sys/module/snd_hda_intel/parameters/power_save_controller
        $ more /sys/module/snd_hda_intel/parameters/power_save

And the following in the beginning with some pause in between.

        $ 
/sys/devices/pci0000.00/0000:00:…/sound/card0/hwC0D0/power_{on,off}_acct

Then `echo -n | aplay` and the above again.

        $ 
/sys/devices/pci0000.00/0000:00:…/sound/card0/hwC0D0/power_{on,off}_acct

Then `aplay some_wave_file.wav`.

        $ 
/sys/devices/pci0000.00/0000:00:…/sound/card0/hwC0D0/power_{on,off}_acct

Then play some music using your favorite music player (MPlayer, Totem, …).

        $ 
/sys/devices/pci0000.00/0000:00:…/sound/card0/hwC0D0/power_{on,off}_acct


Thanks,

Paul


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