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ASoC: DaVinci: Audio: Fix swapping of channels at start of stereo playback

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Fixes swapping of channels at start of stereo playback.

Channel swap can be observed while playing left-only or right-only audio data. The channel
swap is fixed by handling the XSYNCERR condition.

Signed-off-by: Naresh Medisetty <naresh@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
This commit is contained in:
Naresh Medisetty 2008-11-12 10:26:31 +05:30 committed by Mark Brown
parent b402dff873
commit fb0ef645f2
1 changed files with 47 additions and 4 deletions
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51
sound/soc/davinci/davinci-i2s.c
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@ -111,17 +111,60 @@ 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->platform;
u32 w;
int ret;
/* Start the sample generator and enable transmitter/receiver */
w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_GRST, 1);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_XRST, 1);
else
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_RRST, 1);
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, w);
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
/* Stop the DMA to avoid data loss */
/* while the transmitter is out of reset to handle XSYNCERR */
if (platform->pcm_ops->trigger) {
ret = platform->pcm_ops->trigger(substream,
SNDRV_PCM_TRIGGER_STOP);
if (ret < 0)
printk(KERN_DEBUG "Playback DMA stop failed\n");
}
/* Enable the transmitter */
w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_XRST, 1);
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, w);
/* wait for any unexpected frame sync error to occur */
udelay(100);
/* Disable the transmitter to clear any outstanding XSYNCERR */
w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_XRST, 0);
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, w);
/* Restart the DMA */
if (platform->pcm_ops->trigger) {
ret = platform->pcm_ops->trigger(substream,
SNDRV_PCM_TRIGGER_START);
if (ret < 0)
printk(KERN_DEBUG "Playback DMA start failed\n");
}
/* Enable the transmitter */
w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_XRST, 1);
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, w);
} else {
/* Enable the reciever */
w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_RRST, 1);
davinci_mcbsp_write_reg(dev, DAVINCI_MCBSP_SPCR_REG, w);
}
/* Start frame sync */
w = davinci_mcbsp_read_reg(dev, DAVINCI_MCBSP_SPCR_REG);
MOD_REG_BIT(w, DAVINCI_MCBSP_SPCR_FRST, 1);