ASoC: Add support for automatically going to BIAS_OFF on suspend

There is a substantial amount of drivers that in go to SND_SOC_BIAS_OFF on
suspend and go back to SND_SOC_BIAS_SUSPEND on resume (Often this is even
the only thing done in the suspend and resume handlers). This patch
introduces a new suspend_bias_off flag, which when set by a driver will let
the ASoC core automatically put the device's DAPM context at the
SND_SOC_BIAS_OFF level during suspend. Once the device is resumed the DAPM
context will go back to SND_SOC_BIAS_STANDBY (if the context is idle,
otherwise to SND_SOC_BIAS_ON).

This will allow us to remove a fair bit of duplicated code from the drivers.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-dapm.h

@@ -587,7 +587,8 @@ struct snd_soc_dapm_context {
 	enum snd_soc_bias_level suspend_bias_level;
 	struct delayed_work delayed_work;
 	unsigned int idle_bias_off:1; /* Use BIAS_OFF instead of STANDBY */
-
+	/* Go to BIAS_OFF in suspend if the DAPM context is idle */
+	unsigned int suspend_bias_off:1;
 	void (*seq_notifier)(struct snd_soc_dapm_context *,
 			     enum snd_soc_dapm_type, int);
 

include/sound/soc.h

@@ -848,6 +848,7 @@ struct snd_soc_codec_driver {
 	int (*set_bias_level)(struct snd_soc_codec *,
 			      enum snd_soc_bias_level level);
 	bool idle_bias_off;
+	bool suspend_bias_off;
 
 	void (*seq_notifier)(struct snd_soc_dapm_context *,
 			     enum snd_soc_dapm_type, int);

sound/soc/soc-core.c

@@ -4402,6 +4402,7 @@ int snd_soc_register_codec(struct device *dev,
 	codec->component.ignore_pmdown_time = codec_drv->ignore_pmdown_time;
 	codec->dapm.codec = codec;
 	codec->dapm.idle_bias_off = codec_drv->idle_bias_off;
+	codec->dapm.suspend_bias_off = codec_drv->suspend_bias_off;
 	if (codec_drv->seq_notifier)
 		codec->dapm.seq_notifier = codec_drv->seq_notifier;
 	if (codec_drv->set_bias_level)

sound/soc/soc-dapm.c

@@ -1683,6 +1683,22 @@ static void dapm_power_one_widget(struct snd_soc_dapm_widget *w,
 	}
 }
 
+static bool dapm_idle_bias_off(struct snd_soc_dapm_context *dapm)
+{
+	if (dapm->idle_bias_off)
+		return true;
+
+	switch (snd_power_get_state(dapm->card->snd_card)) {
+	case SNDRV_CTL_POWER_D3hot:
+	case SNDRV_CTL_POWER_D3cold:
+		return dapm->suspend_bias_off;
+	default:
+		break;
+	}
+
+	return false;
+}
+
 /*
  * Scan each dapm widget for complete audio path.
  * A complete path is a route that has valid endpoints i.e.:-
@@ -1706,7 +1722,7 @@ static int dapm_power_widgets(struct snd_soc_card *card, int event)
 	trace_snd_soc_dapm_start(card);
 
 	list_for_each_entry(d, &card->dapm_list, list) {
-		if (d->idle_bias_off)
+		if (dapm_idle_bias_off(d))
 			d->target_bias_level = SND_SOC_BIAS_OFF;
 		else
 			d->target_bias_level = SND_SOC_BIAS_STANDBY;
@@ -1772,7 +1788,7 @@ static int dapm_power_widgets(struct snd_soc_card *card, int event)
 		if (d->target_bias_level > bias)
 			bias = d->target_bias_level;
 	list_for_each_entry(d, &card->dapm_list, list)
-		if (!d->idle_bias_off)
+		if (!dapm_idle_bias_off(d))
 			d->target_bias_level = bias;
 
 	trace_snd_soc_dapm_walk_done(card);