ASoC: dwc: Ensure FIFOs are flushed to prevent channel swap

Flush the FIFOs when the stream is prepared for use.  This avoids
an inadvertent swapping of the left/right channels if the FIFOs are
not empty at startup.

Signed-off-by: Andrew Jackson <Andrew.Jackson@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

1 files changed, 14 insertions, 0 deletions

diff --git a/sound/soc/dwc/designware_i2s.c b/sound/soc/dwc/designware_i2s.c
index b93168d4f648..4df19b57429c 100644
--- a/sound/soc/dwc/designware_i2s.c
+++ b/sound/soc/dwc/designware_i2s.c
@@ -263,6 +263,19 @@ static void dw_i2s_shutdown(struct snd_pcm_substream *substream,
         snd_soc_dai_set_dma_data(dai, substream, NULL);
 }
 
+static int dw_i2s_prepare(struct snd_pcm_substream *substream,
+                          struct snd_soc_dai *dai)
+{
+        struct dw_i2s_dev *dev = snd_soc_dai_get_drvdata(dai);
+
+        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+                i2s_write_reg(dev->i2s_base, TXFFR, 1);
+        else
+                i2s_write_reg(dev->i2s_base, RXFFR, 1);
+
+        return 0;
+}
+
 static int dw_i2s_trigger(struct snd_pcm_substream *substream,
                 int cmd, struct snd_soc_dai *dai)
 {
@@ -294,6 +307,7 @@ static struct snd_soc_dai_ops dw_i2s_dai_ops = {
         .startup        = dw_i2s_startup,
         .shutdown       = dw_i2s_shutdown,
         .hw_params      = dw_i2s_hw_params,
+        .prepare        = dw_i2s_prepare,
         .trigger        = dw_i2s_trigger,
 };