ENGR00253290-2 ASoC: imx-wm8962: fix continuous playback distortion issue

  If DAC volume's set to a value that's lower than 0xd8, contineously FLL
setting of wm8962 in machine driver would cause playback distortion issue,
which happens to ENGR219882. so we have to put some another code in machine
driver to prevent distortion issue.

Acked-by: Wang Shengjiu <b02247@freescale.com>
Signed-off-by: Nicolin Chen <b42378@freescale.com>

1 files changed, 48 insertions, 0 deletions

diff --git a/sound/soc/imx/imx-wm8962.c b/sound/soc/imx/imx-wm8962.c
index 23f9a17588cb..a19e5273563d 100644
--- a/sound/soc/imx/imx-wm8962.c
+++ b/sound/soc/imx/imx-wm8962.c
@@ -53,6 +53,8 @@ struct imx_priv {
 	int amic_irq;
 	int amic_status;
 	struct platform_device *pdev;
+	struct snd_pcm_substream *first_stream;
+	struct snd_pcm_substream *second_stream;
 };
 unsigned int sample_format = SNDRV_PCM_FMTBIT_S16_LE;
 static struct imx_priv card_priv;
@@ -126,6 +128,11 @@ static int imx_hifi_hw_params(struct snd_pcm_substream *substream,
 	u32 dai_format;
 	unsigned int pll_out;
 
+	if (!priv->first_stream)
+		priv->first_stream = substream;
+	else
+		priv->second_stream = substream;
+
 	dai_format = SND_SOC_DAIFMT_I2S | SND_SOC_DAIFMT_NB_NF |
 		SND_SOC_DAIFMT_CBM_CFM;
 
@@ -174,6 +181,43 @@ static int imx_hifi_hw_params(struct snd_pcm_substream *substream,
 	return 0;
 }
 
+
+static int imx_hifi_hw_free(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_dai *codec_dai = rtd->codec_dai;
+	struct imx_priv *priv = &card_priv;
+	int ret;
+
+	if (priv->first_stream == substream)
+		priv->first_stream = priv->second_stream;
+	priv->second_stream = NULL;
+
+	if (!priv->first_stream) {
+		/*
+		 * wm8962 doesn't allow us to continuously setting FLL,
+		 * So we set MCLK as sysclk once, which'd remove the limitation.
+		 */
+		ret = snd_soc_dai_set_sysclk(codec_dai, WM8962_SYSCLK_MCLK,
+				0, SND_SOC_CLOCK_IN);
+		if (ret < 0) {
+			pr_err("Failed to set SYSCLK: %d\n", ret);
+			return ret;
+		}
+
+		/*
+		 * Continuously setting FLL would cause playback distortion.
+		 * We can fix it just by mute codec after playback.
+		 */
+		ret = snd_soc_dai_digital_mute(codec_dai, 1);
+		if (ret < 0) {
+			pr_err("Failed to set MUTE: %d\n", ret);
+			return ret;
+		}
+	}
+	return 0;
+}
+
 static void imx_resume_event(struct work_struct *wor)
 {
 	struct imx_priv *priv = &card_priv;
@@ -433,6 +477,7 @@ static struct snd_soc_ops imx_hifi_ops = {
 	.startup = imx_hifi_startup,
 	.shutdown = imx_hifi_shutdown,
 	.hw_params = imx_hifi_hw_params,
+	.hw_free = imx_hifi_hw_free,
 	.trigger = imx_hifi_trigger,
 };
 
@@ -497,6 +542,9 @@ static int __devinit imx_wm8962_probe(struct platform_device *pdev)
 
 	priv->sysclk = plat->sysclk;
 
+	priv->first_stream = NULL;
+	priv->second_stream = NULL;
+
 	return ret;
 }