[alsa-devel] [PATCH 2/3] ALSA: hda - WAKEEN feature enabling for runtime pm

[Takashi Iwai]

At Tue, 23 Jul 2013 08:09:02 +0000,
Wang, Xingchao wrote:
> 
> > >
> > > Signed-off-by: Wang Xingchao <xingchao.wang at linux.intel.com>
> > > ---
> > >   sound/pci/hda/hda_intel.c | 25 +++++++++++++++++++++++++
> > >   1 file changed, 25 insertions(+)
> > >
> > > diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> > > index 8860dd5..a7ac7fd 100644
> > > --- a/sound/pci/hda/hda_intel.c
> > > +++ b/sound/pci/hda/hda_intel.c
> > > @@ -2970,6 +2970,11 @@ static int azx_runtime_suspend(struct device
> > *dev)
> > >   {
> > >   	struct snd_card *card = dev_get_drvdata(dev);
> > >   	struct azx *chip = card->private_data;
> > > +	int status;
> > > +
> > > +	/* enable controller wake up event */
> > > +	azx_writew(chip, WAKEEN, azx_readw(chip, WAKEEN) |
> > > +		  STATESTS_INT_MASK);
> > >
> > >   	azx_stop_chip(chip);
> > >   	azx_enter_link_reset(chip);
> > > @@ -2983,11 +2988,31 @@ static int azx_runtime_resume(struct device
> > *dev)
> > >   {
> > >   	struct snd_card *card = dev_get_drvdata(dev);
> > >   	struct azx *chip = card->private_data;
> > > +	struct hda_bus *bus;
> > > +	struct hda_codec *codec;
> > > +	int status;
> > >
> > >   	if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
> > >   		hda_display_power(true);
> > > +
> > > +	/* Read STATESTS before controller reset */
> > > +	status = azx_readw(chip, STATESTS);
> > > +
> > >   	azx_init_pci(chip);
> > >   	azx_init_chip(chip, 1);
> > > +
> > > +	bus = chip->bus;
> > > +	if (status && bus) {
> > > +		list_for_each_entry(codec, &bus->codec_list, list)
> > > +			if (status & (1 << codec->addr))
> > > +				queue_delayed_work(codec->bus->workq,
> > > +						   &codec->jackpoll_work,
> > codec->jackpoll_interval);
> > 
> > Is there a reason you want to move the jack detection to a delayed work, i e,
> > why can't we just call:
> > 
> >   	snd_hda_jack_set_dirty_all(codec);
> >   	snd_hda_jack_poll_all(codec);
> > 
> > ...from here?
> 
> In fact it doesnot work for me, It will again call runtime_resume() and caused dead loop.

It means that the power refcount is messed up by this way.

When a verb is executed, the codec goes to a full resume mode, which
turns up the controller, eventually calling azx_power_notify().
In azx_power_notify(), pm_runtime_{get|put}_sync() is called
accordingly, which again goes to runtime resume.  A quick fix would be
to add a flag or something to avoid reentrace.

But, calling the jackpoll in the resume is basically superfluous.
As already mentioned, issuing a verb itself triggers the full resume,
and this already includes the update of the whole jack status.
Thus, executing jackpoll at that place means to perform the jack
polling twice.

In other words, what's we need to achieve is just to call
snd_hda_resume() appropriately in the runtime resume case.
Of course, this will need more fixes for avoiding reentrance, etc.

But, it leads to another question: do we need a full resume just for
jack detection and user-space notification?  Just reading the pin
detect state should be able to run even in D3 (for chips that are
capable of it), and the notification itself doesn't need any audio
hardware action.


Takashi