Playing 24-bit format file leads to channel swap on mx28 and the reason is that the current driver performs one write/read to/from the SAIF_DATA register to trigger the transfer.
This approach works fine for S16_LE case because SAIF_DATA is a 32-bit register and thus is capable of storing the 16-bit left and right channels, but for the S24_LE case it can only store one channel, so in order to not lose the FIFO sync an extra read/write is needed.
Reported-by: Dan Winner DWinner@tc-helicon.com Signed-off-by: Fabio Estevam fabio.estevam@freescale.com Tested-by: Dan Winner DWinner@tc-helicon.com --- Changes since v1: - Clarify that the extra read/write is also safe for non 24-bit formats.
sound/soc/mxs/mxs-saif.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/sound/soc/mxs/mxs-saif.c b/sound/soc/mxs/mxs-saif.c index aa037b2..0eb2883 100644 --- a/sound/soc/mxs/mxs-saif.c +++ b/sound/soc/mxs/mxs-saif.c @@ -523,16 +523,24 @@ static int mxs_saif_trigger(struct snd_pcm_substream *substream, int cmd,
if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) { /* - * write a data to saif data register to trigger - * the transfer + * write data to saif data register to trigger + * the transfer. + * For 24-bit format the 32-bit FIFO register stores + * only one channel, so we need to write twice. + * This is also safe for the other non 24-bit formats. */ __raw_writel(0, saif->base + SAIF_DATA); + __raw_writel(0, saif->base + SAIF_DATA); } else { /* - * read a data from saif data register to trigger - * the receive + * read data from saif data register to trigger + * the receive. + * For 24-bit format the 32-bit FIFO register stores + * only one channel, so we need to read twice. + * This is also safe for the other non 24-bit formats. */ __raw_readl(saif->base + SAIF_DATA); + __raw_readl(saif->base + SAIF_DATA); }
master_saif->ongoing = 1;