[PATCH 3.18 024/150] ASoC: dwc: Ensure FIFOs are flushed to prevent channel swap
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2015-01-14 08:49:45
Also in:
lkml
3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrew Jackson <redacted> 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 <redacted> Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- sound/soc/dwc/designware_i2s.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
--- 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_p 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 .startup = dw_i2s_startup, .shutdown = dw_i2s_shutdown, .hw_params = dw_i2s_hw_params, + .prepare = dw_i2s_prepare, .trigger = dw_i2s_trigger, };