[alsa-devel] [PATCH] ASoC: pandora: switch clock back to internal on stop

[Grazvydas Ignotas]

For some reason, OMAP doesn't enter lower power states with functional
clock (CLKS) source set to external, so switch it back to internal when
done playing.

Signed-off-by: Grazvydas Ignotas <notasas at gmail.com>
---
 sound/soc/omap/omap3pandora.c |   22 ++++++++++++++++++++++
 1 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/sound/soc/omap/omap3pandora.c b/sound/soc/omap/omap3pandora.c
index 07794bd..1be26df 100644
--- a/sound/soc/omap/omap3pandora.c
+++ b/sound/soc/omap/omap3pandora.c
@@ -77,6 +77,27 @@ static int omap3pandora_hw_params(struct snd_pcm_substream *substream,
 	return 0;
 }
 
+static int omap3pandora_hw_free(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
+	int ret;
+
+	/*
+	 * For some reason, if we don't set clock back to internal, OMAP power
+	 * saving features don't work properly (per power domain doesn't enter
+	 * lower power states). Switch it back until better solution is found.
+	 */
+	ret = snd_soc_dai_set_sysclk(cpu_dai, OMAP_MCBSP_SYSCLK_CLKS_FCLK,
+				     0, SND_SOC_CLOCK_IN);
+	if (ret < 0) {
+		pr_err(PREFIX "can't set cpu system clock\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static int omap3pandora_dac_event(struct snd_soc_dapm_widget *w,
 	struct snd_kcontrol *k, int event)
 {
@@ -201,6 +222,7 @@ static int omap3pandora_in_init(struct snd_soc_pcm_runtime *rtd)
 
 static struct snd_soc_ops omap3pandora_ops = {
 	.hw_params = omap3pandora_hw_params,
+	.hw_free = omap3pandora_hw_free,
 };
 
 /* Digital audio interface glue - connects codec <--> CPU */
-- 
1.7.0.4