[alsa-devel] snd-hda-intel runtime PM fail after module reload

[Takashi Iwai]

On Thu, 25 Feb 2016 22:57:34 +0100,
Ville Syrjälä wrote:
> 
> On Thu, Feb 25, 2016 at 09:28:59PM +0100, Takashi Iwai wrote:
> > On Thu, 25 Feb 2016 20:19:08 +0100,
> > Ville Syrjälä wrote:
> > > 
> > > Hi,
> > > 
> > > My investigation into some sporadic i915 runtime PM failures seem to
> > > point the finger at snd-hda-intel.
> > > 
> > > I just tried to play around unloding and reloading snd-hda-intel and
> > > sometimes I get snd-hda-intel loaded with runtime PM supposedly enabled,
> > > but actually the device won't runtime suspend. At which point frobbing
> > > with power/control is enough to kick it back into submission.
> > 
> > Which platform are you testing?  If it's SKL, BSW or later, multiple
> > codecs are on a single HD-audio bus.  In general, you have to adjust
> > the runtime PM of all these codecs in addition to the runtime PM of
> > the controller.  Some of them are immediately runtime PM enabled but
> > some of them aren't, left the default as is.
> 
> This was on a HSW.

OK, then the HDMI/DP has its own controller.

> I also have CONFIG_SND_HDA_POWER_SAVE_DEFAULT=1 which I presume should
> enable codec power saving by deafault?

Yes, unless something overwrites it.  Often there are udev rules to
override something for that.

> > It might be that your desktop environment adjusts the runtime PM of
> > HD-audio stuff, often depending on the power state.  But when you
> > reload, this adjustment is also lost, so you'd have to adjust
> > manually.
> 
> There's no desktop environment. Well, unless you count systemd as such.
> As you can see from the log I included at least the pci device power/control
> file stayed at 'auto' the whole time until I flipped it to 'on' and then
> back to 'auto' to fix the problem.

It implies that the problem is the PM layer itself...

> Also the problem didn't happen on every reload AFAICS, so there's
> something rather non-deterministic happening.

In anyway, please check the runtime PM status in the codec devices,
i.e. /sys/bus/hdaudio/devices/*.   The controller runtime PM is
activated only when the codec is power-saved.

If the codec is in runtime-suspended but the controller still doesn't,
put some debug codes in azx_runtime_idle() in
sound/pci/hda/hda_intel.c, whether any EBUSY condition there hits.


Takashi