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.
Thanks,
Paul
[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
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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
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