[alsa-devel] [RFC PATCH 1/1] ASoC: soc-core: symmetry checking for each DAIs separately

[Dong Aisheng]

The orginal code does not cover the case that one DAI such as codec
may be shared between other two DAIs(CPU).
When do symmetry checking, altough the codec DAI requires symmetry,
the two CPU DAIs may still be configured to run on different rates.

We change to check each DAI's state separately instead of only checking
the dai link to prevent this issue.

Signed-off-by: Dong Aisheng <b29396 at freescale.com>
Cc: Mark Brown <broonie at opensource.wolfsonmicro.com>
Cc: Liam Girdwood <lrg at ti.com>
Cc: Sascha Hauer <s.hauer at pengutronix.de>
Cc: Wolfram Sang <w.sang at pengutronix.de>
Cc: Lars-Peter Clausen <lars at metafoo.de>

---
 include/sound/soc-dai.h |    3 ++
 include/sound/soc.h     |    2 -
 sound/soc/soc-pcm.c     |   64 +++++++++++++++++++++++++++++++++-------------
 3 files changed, 49 insertions(+), 20 deletions(-)

diff --git a/include/sound/soc-dai.h b/include/sound/soc-dai.h
index 5ad5f3a..844d4ed 100644
--- a/include/sound/soc-dai.h
+++ b/include/sound/soc-dai.h
@@ -242,6 +242,9 @@ struct snd_soc_dai {
 	void *playback_dma_data;
 	void *capture_dma_data;
 
+	/* Symmetry data */
+	unsigned int rate;
+
 	/* parent platform/codec */
 	union {
 		struct snd_soc_platform *platform;
diff --git a/include/sound/soc.h b/include/sound/soc.h
index 3fe658e..5449139 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -849,8 +849,6 @@ struct snd_soc_pcm_runtime  {
 	unsigned int complete:1;
 	unsigned int dev_registered:1;
 
-	/* Symmetry data - only valid if symmetry is being enforced */
-	unsigned int rate;
 	long pmdown_time;
 
 	/* runtime devices */
diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index 1aee9fc..3f7ded7 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -32,33 +32,54 @@ static int soc_pcm_apply_symmetry(struct snd_pcm_substream *substream)
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_soc_dai *cpu_dai = rtd->cpu_dai;
 	struct snd_soc_dai *codec_dai = rtd->codec_dai;
+	unsigned int race;
+	unsigned int force_rate;
 	int ret;
 
+	race = 0;
+	force_rate = 0;
+
 	if (!codec_dai->driver->symmetric_rates &&
 	    !cpu_dai->driver->symmetric_rates &&
 	    !rtd->dai_link->symmetric_rates)
 		return 0;
 
+	if (codec_dai->active && codec_dai->driver->symmetric_rates ||
+	     codec_dai->active && rtd->dai_link->symmetric_rates) {
+		if (codec_dai->rate != 0)
+			force_rate = codec_dai->rate;
+		else
+			race = 1;
+	}
+
+	if (cpu_dai->active && cpu_dai->driver->symmetric_rates ||
+	    codec_dai->active && rtd->dai_link->symmetric_rates) {
+		if (cpu_dai->rate != 0)
+			force_rate = cpu_dai->rate;
+		else
+			race = 1;
+	}
+
+	if (force_rate) {
+		dev_dbg(&rtd->dev, "Symmetry forces %dHz rate\n", rtd->rate);
+
+		ret = snd_pcm_hw_constraint_minmax(substream->runtime,
+				SNDRV_PCM_HW_PARAM_RATE,
+				force_rate, force_rate);
+		if (ret < 0) {
+			dev_err(&rtd->dev,
+				"Unable to apply rate symmetry constraint: %d\n", ret);
+			return ret;
+		}
+	}
+
 	/* This can happen if multiple streams are starting simultaneously -
 	 * the second can need to get its constraints before the first has
 	 * picked a rate.  Complain and allow the application to carry on.
 	 */
-	if (!rtd->rate) {
+	if (race)
 		dev_warn(&rtd->dev,
-			 "Not enforcing symmetric_rates due to race\n");
-		return 0;
-	}
-
-	dev_dbg(&rtd->dev, "Symmetry forces %dHz rate\n", rtd->rate);
-
-	ret = snd_pcm_hw_constraint_minmax(substream->runtime,
-					   SNDRV_PCM_HW_PARAM_RATE,
-					   rtd->rate, rtd->rate);
-	if (ret < 0) {
-		dev_err(&rtd->dev,
-			"Unable to apply rate symmetry constraint: %d\n", ret);
-		return ret;
-	}
+			"Not enforcing symmetric_rates due to race\n");
 
 	return 0;
 }
@@ -287,9 +308,14 @@ static int soc_pcm_close(struct snd_pcm_substream *substream)
 	cpu_dai->active--;
 	codec_dai->active--;
 	codec->active--;
+	rtd->active--;
+
+	/* clear the corresponding DAIs rate when inactive */
+	if (!cpu_dai->active)
+		cpu_dai->rate = 0;
 
-	if (!cpu_dai->active && !codec_dai->active)
-		rtd->rate = 0;
+	if (!codec_dai->active)
+		codec_dai->rate = 0;
 
 	/* Muting the DAC suppresses artifacts caused during digital
 	 * shutdown, for example from stopping clocks.
@@ -447,7 +473,9 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream,
 		}
 	}
 
-	rtd->rate = params_rate(params);
+	/* store the rate for each DAIs */
+	cpu_dai->rate = params_rate(params);
+	codec_dai->rate = params_rate(params);
 
 out:
 	mutex_unlock(&rtd->pcm_mutex);
-- 
1.7.0.4