[alsa-devel] [RFC PATCH v2 1/2] ASoC: refine ASoC hdmi audio suspend/resume

[Takashi Iwai]

On Fri, 11 Jan 2019 14:34:34 +0100,
Takashi Iwai wrote:
> 
> On Fri, 11 Jan 2019 06:20:23 +0100,
> Yang, Libin wrote:
> > 
> > The below patch may have a small confliction that the trigger will be 
> > called twice as our SOF has already call snd_pcm_suspend() in card
> > suspend.
> 
> It should be no problem, snd_pcm_suspend() can be called multiple
> times.  If it's already suspended, just nothing happens.

Thinking of this problem again, does a patch like below work instead?
This looks like a better and more generic solution.

What I'm not quite sure is whether the device suspend order between
PCM device and HD-audio codec device is guaranteed.  I guess yes,
because the PCM device is registered always after the codec.  But ASoC
might have another weirdness :)

If this patch works, basically we can get rid of all external callers
of snd_pcm_suspend() & co.  That'll be a nice cleanup.


thanks,

Takashi

---
diff --git a/sound/core/pcm.c b/sound/core/pcm.c
index 01b9d62eef14..d8d57336b8b8 100644
--- a/sound/core/pcm.c
+++ b/sound/core/pcm.c
@@ -683,6 +683,25 @@ static inline int snd_pcm_substream_proc_done(struct snd_pcm_substream *substrea
 
 static const struct attribute_group *pcm_dev_attr_groups[];
 
+#ifdef CONFIG_PM_SLEEP
+static int do_pcm_suspend(struct device *dev)
+{
+	struct snd_pcm_str *pstr = container_of(dev, struct snd_pcm_str, dev);
+
+	snd_pcm_suspend_all(pstr->pcm);
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops pcm_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(do_pcm_suspend, NULL)
+};
+
+static const struct device_type pcm_dev_type = {
+	.name = "pcm",
+	.pm = &pcm_dev_pm_ops,
+};
+
 /**
  * snd_pcm_new_stream - create a new PCM stream
  * @pcm: the pcm instance
@@ -713,6 +732,7 @@ int snd_pcm_new_stream(struct snd_pcm *pcm, int stream, int substream_count)
 
 	snd_device_initialize(&pstr->dev, pcm->card);
 	pstr->dev.groups = pcm_dev_attr_groups;
+	pstr->dev.type = &pcm_dev_type;
 	dev_set_name(&pstr->dev, "pcmC%iD%i%c", pcm->card->number, pcm->device,
 		     stream == SNDRV_PCM_STREAM_PLAYBACK ? 'p' : 'c');