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>

1 files changed, 25 insertions, 6 deletions

diff --git a/sound/soc/davinci/davinci-i2s.c b/sound/soc/davinci/davinci-i2s.c
index bf5ec4b2f7f5..dd44167a90f0 100644
--- a/sound/soc/davinci/davinci-i2s.c
+++ b/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);