[PATCH v2 2/6] ASoC: dwc: Ensure FIFOs are flushed to prevent channel swap
From: lars@metafoo.de (Lars-Peter Clausen)
Date: 2014-12-12 09:37:39
Also in:
alsa-devel, lkml
On 12/12/2014 10:25 AM, Andrew Jackson wrote:
quoted hunk ↗ jump to hunk
From: Andrew Jackson <redacted> If the FIFOs aren't flushed, the left/right channels may be swapped: this may occur if the FIFOs are not empty when the streams start. Signed-off-by: Andrew Jackson <redacted> --- sound/soc/dwc/designware_i2s.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)diff --git a/sound/soc/dwc/designware_i2s.c b/sound/soc/dwc/designware_i2s.c index ef771ea..b9d6a25 100644 --- a/sound/soc/dwc/designware_i2s.c +++ b/sound/soc/dwc/designware_i2s.c@@ -228,12 +228,14 @@ static int dw_i2s_hw_params(struct snd_pcm_substream *substream, i2s_disable_channels(dev, substream->stream); if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) { + i2s_write_reg(dev->i2s_base, TXFFR, 1); i2s_write_reg(dev->i2s_base, TCR(ch_reg), xfer_resolution); i2s_write_reg(dev->i2s_base, TFCR(ch_reg), 0x02); irq = i2s_read_reg(dev->i2s_base, IMR(ch_reg)); i2s_write_reg(dev->i2s_base, IMR(ch_reg), irq & ~0x30); i2s_write_reg(dev->i2s_base, TER(ch_reg), 1); } else { + i2s_write_reg(dev->i2s_base, RXFFR, 1); i2s_write_reg(dev->i2s_base, RCR(ch_reg), xfer_resolution); i2s_write_reg(dev->i2s_base, RFCR(ch_reg), 0x07); irq = i2s_read_reg(dev->i2s_base, IMR(ch_reg));
This should probably go into the prepare callback. prepare is for example also called when recovering from a underrun/overrun. Whereas hwparams is only called during initial setup of the stream.