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

commit 3475c3d034d7f276a474c8bd53f44b48c8bf669d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/sound/soc/dwc/designware_i2s.c b/sound/soc/dwc/designware_i2s.c
index 593a3ea12d4c3cca61caa6976d94847478a0c6dc..489a9abf112b1431769fd4822fc4362b0e005c4e 100644 (file)
--- 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,
 };