[alsa-devel] HD-audio runtime PM

David Henningsson david.henningsson at canonical.com
Mon Nov 25 11:25:46 CET 2013

On 11/25/2013 10:26 AM, Takashi Iwai wrote:
> At Mon, 25 Nov 2013 10:20:55 +0100,
> David Henningsson wrote:
>> On 11/25/2013 08:17 AM, Takashi Iwai wrote:
>>> At Mon, 25 Nov 2013 07:32:57 +0100,
>>> David Henningsson wrote:
>>>> On 11/22/2013 12:57 PM, Takashi Iwai wrote:
>>>>> Hi,
>>>>> after my previous fix, the runtime PM seems working stably finally.
>>>>> However, there seem still some glitches:
>>>>> 1. The wakeup via jack or HDMI/DP detection doesn't seem to work on my
>>>>>   test machines.  WAKEEN is set properly.  And its value can be read
>>>>>   correctly at the point of runtime resume, too.
>>>> Hi and thanks for working on this.
>>>> I've been trying to reproduce the above, but I can't seem to activate
>>>> runtime PM at all. I can't seem to get a callback to runtime_suspend,
>>>> and further investigation shows that
>>>> /sys/class/sound/card0/power/runtime_status shows "unsupported".
>>> You need to adjust power/control of the parent PCM device,
>>> i.e. /sys/devices/pci/*/power/control.  The following udev rule should
>>> work for HD-audio.  Give it a try.
>>>   ACTION=="add", SUBSYSTEM=="pci", ATTR{class}=="0x040300", TEST=="power/control", ATTR{power/control}="auto"
>> I tried this rule, but it did not make any difference -
>> /sys/class/sound/card0/device/power/control was still on. (And I did
>> proofread the rule...)
> This (and other sound/*) doesn't matter.  Only the entry in the PCI
> device counts.  It's the runtime PM of the PCI device after all.
> (Remember that the runtime PM callbacks are set only on this device.)

But /sys/class/sound/card0/device is just a symlink for
/sys/devices/pci0000:00/0000:00:03.0 - is this not the PCI device you're
talking about?

Anyway, power/runtime_status is always active, and power/usage_count is
always 1. (And pulseaudio is not running, and nothing else is using any
/dev/snd/* files.)

> You can put a printk in azx_runtime_suspend().  For Haswell, it should
> work as is with 3.13-rc1.

I guess I could test that, but I doubt it would help...

> For IvyBridge, check sound-unstable test/hda branch.  I'll try to
> merge to sound git tree once after brushing up and submitting for
> review.

Ok. I currently have nothing Ivybridge to check with.

David Henningsson, Canonical Ltd.

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