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

Sat Nov 17 11:53:49 CET 2012

At Sat, 17 Nov 2012 01:48:47 +0100,
Tomas Pospisek wrote:
> 
> Hello,
> 
> On Fri, 16 Nov 2012 17:04:03 +0100, Takashi Iwai <tiwai at suse.de> wrote:
> > At Fri, 16 Nov 2012 15:23:06 +0100, Tomas Pospisek wrote:
> >> 
> >> The kernel of the upcoming Debian release and some
> >> recent kernels of Ubuntu seem to be suffering from HDA
> >> running at full force upon wakeup and producing
> >> a lot of heat (keeping the fan spinning loudly).
> > 
> > What do you mean "wakeup"?
> 
> Waking up from suspend to RAM.

And does the same issue occur on hibernation, too?
Basically both S2RAM and S2DISK use the same suspend/resume path
regarding the sound driver, so the behavior should be consistent in
both cases.

> >  Which kernel are you using?
> 
> 3.2.0-4-amd64 from Debian wheezy:
>   http://packages.debian.org/wheezy/linux-image-3.2.0-4-amd64

OK, could you check the latest Linus tree (at least 3.7-rc5) whether
the problem is still present?  If it is, please keep using it for the
further testing instead of 3.2.0.  3.2.0 is way too old to debug
primarily.

Also, try the latest alsa-lib from git tree, too.  I thought David
provides some packages built from the latest repo?

> > Which codec and HD-audio controller chips?
> 
> Wrt codec - I don't know. Before suspending I am not playing any sound.

Well, I meant the audio codec chip, not the codec format :)
But in the text below, you showed a conexant codec.

Also, it's important to know what h/w vendor and model are.
I guess it's a Lenovo machine?

> And the
> system (say the desktop system or the bell in a terminal) isn't producing
> any sound either.

OK.

> Powertop says "Audio codec hwC0D0: IDT". Other People in the launchpad
> bugtracker seem to be reporting either "hwC0D0: IDT", "hwC0D0: Conexant" or
> "hwC0D1: Conexant". 
> 
>   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/877560
> 
> Here's the chip:
> 
> Audio:
> 00:1b.0 Audio device: Intel Corporation 6 Series/C200 Series Chipset
> Family High Definition Audio Controller (rev 05)
> 
> >  Please elaborate a bit more instead of a bug track URL.  This will save
> lots of time for other people.
> 
> Powertop v2.0 shows:
> in the Overview tab:
>                 Usage       Events/s    Category       Description
>             100.0%                      Device         Audio codec hwC0D0:
> IDT

The usage in powertop doesn't mean what actually consuming the power
in 100%.  It's a completely different statistics from the CPU usage.

It shows that the sound driver hasn't gone into the power-saving
mode, a sort of partial suspend of the device.  It can happen by
various reasons: e.g. when your system doesn't set up the power_save
option properly, or your mixer setup blocks it.

First off, check the value in
/sys/module/snd_hda_intel/parameters/power_save.  If it shows 0, it
means the power-saving feature is turned off.  If it's a positive
value, it means the power-saving may be turned on after the specified
seconds after closing all usages of sound devices.

Then check "fuser /dev/snd/pcm*" (run as root).  If this shows
something, the PCM device is still being used, so the power-saving
can't be activated.

If nothing is using the PCM device, but still no power-saving is
activated, check the mixer setup.  Check "amixer -c0 contents", and
see whether any element with "Playback Switch" string is turned on.
If anything else than "Speaker", "Headphone", "Master" (or sometimes
"Front" or "Surround", too) is turned on, this is likely an analog
loopback control, which constantly blocks the power-saving feature.
Turn them off.

If nothing still helps, give alsa-info.sh output at this state.

> in Tunable tab:
>    Good          Runtime PM for PCI Device Intel Corporation 6 Series/C200
> Series Chipset Family High Definition Audio Controller
> 
> Top shows:
> top - 01:12:28 up 4 days,  4:10,  3 users,  load average: 0.04, 0.14, 0.21
> Tasks: 181 total,   2 running, 179 sleeping,   0 stopped,   0 zombie
> %Cpu(s):  0.2 us,  0.3 sy,  0.0 ni, 99.5 id,  0.0 wa,  0.0 hi,  0.0 si, 
> 0.0 st
> KiB Mem:   4007896 total,  3773420 used,   234476 free,   266220 buffers
> KiB Swap:  8280060 total,      272 used,  8279788 free,  2096072 cached
> 
> If I start alsamixer and press "F5" (nothing else!), the previous number
> in powertop will go down to:
> 
>                 Usage       Events/s    Category       Description
>               0.0%        Audio codec hwC0D0: IDT
> 
> after about 5 seconds.

Again, this doesn't mean that your machine is consuming too much
power.  But please check the behavior at first with the latest 3.7-rc5
kernel.

> I have tried also tried the following workaround:
> 
>   echo 1 | sudo tee /sys/module/snd_hda_intel/parameters/power_save
>   echo Y | sudo tee
> /sys/module/snd_hda_intel/parameters/power_save_controller
> 
> mentioned in Ubuntu's Launchpad:
>   
>   https://bugs.launchpad.net/ubuntu/+source/linux/+bug/877560/comments/37
> 
> but that had no visible impact.

In the earlier kernel before 3.7, setting the power_save option alone
doesn't trigger the power-saving mode.  It's activated after the first
use of the device.  But this was improved in 3.7 kernel so that the
power-saving is kicked off immediately.

Takashi

> The bug is a regression, since I did not have the problem under the
> previous Ubuntu
> Precise installation. However I *think* I was running a non-standard
> kernel there (my HD crashed, so I can't verify this assertion).
> 
> > If it's really a CPU usage, try to run perf and check what is spinning
> > around.
> 
> I ran "perf top", but I can't find anything interesting there:
> 
> Events: 8K cycles
> 
>  15.69%  libxul.so                      [.] 0x9c31ae
>  12.49%  libmozjs.so.10d                [.] 0xd4f72
>   7.38%  [kernel]                       [k] intel_idle
>   3.15%  powertop                       [.] 0x283ae
>   2.40%  Xorg (deleted)                 [.] 0xc3894
>   2.26%  libc-2.13.so                   [.] 0x786ea
>   1.41%  libQtCore.so.4.8.2             [.] 0xbc8fb
>   ...
> 
> Thanks,
> *t
> 
> >> The bug tracking can be found here:
> >> 
> >>     https://bugs.launchpad.net/ubuntu/+source/linux/+bug/877560
> >> 
> >> is there anything known about this problem? What the root of
> >> the problem is? How to solve it? Are there patches? Are there
> >> kernels that have fixed the problem? Are there workarounds?
> >> 
> >> The problem seems to be impacting quite a few users.
> >> *t
> >> _______________________________________________
> >> Alsa-devel mailing list
> >> Alsa-devel at alsa-project.org
> >> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
> >>
> 