ASoC: DaVinci: i2s toggle clock to complete reset

Add toggle_clock function to complete i2s reset earlier.
Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/davinci/davinci-i2s.c

@@ -104,6 +104,7 @@ static struct davinci_pcm_dma_params davinci_i2s_pcm_in = {
 
 struct davinci_mcbsp_dev {
 	void __iomem			*base;
+	u32				pcr;
 	struct clk			*clk;
 	struct davinci_pcm_dma_params	*dma_params[2];
 };
@@ -119,17 +120,34 @@ static inline u32 davinci_mcbsp_read_reg(struct davinci_mcbsp_dev *dev, int reg)
 	return __raw_readl(dev->base + reg);
 }
 
+static void toggle_clock(struct davinci_mcbsp_dev *dev, int playback)
+{
+	u32 m = playback ? DAVINCI_MCBSP_PCR_CLKXP : DAVINCI_MCBSP_PCR_CLKRP;
+	/* The clock needs to toggle to complete reset.
+	 * So, fake it by toggling the clk polarity.
+	 */
+	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, dev->pcr ^ m);
+	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, dev->pcr);
+}
+
 static void davinci_mcbsp_start(struct snd_pcm_substream *substream)
 {
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct davinci_mcbsp_dev *dev = rtd->dai->cpu_dai->private_data;
 	struct snd_soc_device *socdev = rtd->socdev;
 	struct snd_soc_platform *platform = socdev->card->platform;
+	int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
 	u32 spcr;
 	int ret;
-
-	/* Start the sample generator and enable transmitter/receiver */
+	u32 mask = playback ? DAVINCI_MCBSP_SPCR_XRST : DAVINCI_MCBSP_SPCR_RRST;
 	spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
+	if (spcr & mask) {
+		/* start off disabled */
+		davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG,
+				spcr & ~mask);
+		toggle_clock(dev, playback);
+	}
+	/* Start the sample generator and enable transmitter/receiver */
 	spcr |= DAVINCI_MCBSP_SPCR_GRST;
 	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
 
@@ -155,6 +173,7 @@ static void davinci_mcbsp_start(struct snd_pcm_substream *substream)
 		spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
 		spcr &= ~DAVINCI_MCBSP_SPCR_XRST;
 		davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
+		toggle_clock(dev, playback);
 
 		/* Restart the DMA */
 		if (platform->pcm_ops->trigger) {
@@ -188,15 +207,14 @@ static void davinci_mcbsp_stop(struct snd_pcm_substream *substream)
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct davinci_mcbsp_dev *dev = rtd->dai->cpu_dai->private_data;
 	u32 spcr;
+	int playback = (substream->stream == SNDRV_PCM_STREAM_PLAYBACK);
 
 	/* Reset transmitter/receiver and sample rate/frame sync generators */
 	spcr = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
 	spcr &= ~(DAVINCI_MCBSP_SPCR_GRST | DAVINCI_MCBSP_SPCR_FRST);
-	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
-		spcr &= ~DAVINCI_MCBSP_SPCR_XRST;
-	else
-		spcr &= ~DAVINCI_MCBSP_SPCR_RRST;
+	spcr &= playback ? ~DAVINCI_MCBSP_SPCR_XRST : ~DAVINCI_MCBSP_SPCR_RRST;
 	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, spcr);
+	toggle_clock(dev, playback);
 }
 
 static int davinci_i2s_startup(struct snd_pcm_substream *substream,
@@ -334,6 +352,7 @@ static int davinci_i2s_set_dai_fmt(struct snd_soc_dai *cpu_dai,
 		return -EINVAL;
 	}
 	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SRGR_REG, srgr);
+	dev->pcr = pcr;
 	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_PCR_REG, pcr);
 	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_RCR_REG, rcr);
 	davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_XCR_REG, xcr);