[alsa-devel] [PATCH 1/3] ASoC:soc-pcm:fix a codec fixup issue in TDM case

[Rander Wang]

On HDaudio platforms, if playback is started when capture is working,
there is no audible output. 

This can be root-caused to the use of the rx|tx_mask to store an HDaudio
stream tag.

If capture is stared before playback, rx_mask would be non-zero on HDaudio
platform, then the channel number of playback, which is in the same codec
dai with the capture, would be changed by soc_pcm_codec_params_fixup based
on the tx_mask at first, then overwritten by this function based on rx_mask
at last.

According to the author of tx|rx_mask, tx_mask is for playback and rx_mask 
is for capture. And stream direction is checked at all other references of
tx|rx_mask in ASoC, so here should be an error. This patch checks stream 
direction for tx|rx_mask for fixup function.

This issue would affect not only HDaudio+ASoC, but also I2S codecs if the
channel number based on rx_mask is not equal to the one for tx_mask. It could
be rarely reproduecd because most drivers in kernel set the same channel number
to tx|rx_mask or rx_mask is zero.

Tested on all platforms using stream_tag & HDaudio and intel I2S platforms.

Signed-off-by: Rander Wang <rander.wang at linux.intel.com>
---
 sound/soc/soc-pcm.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-pcm.c b/sound/soc/soc-pcm.c
index a5b40e82dea4..e70555a4ea06 100644
--- a/sound/soc/soc-pcm.c
+++ b/sound/soc/soc-pcm.c
@@ -954,10 +954,13 @@ static int soc_pcm_hw_params(struct snd_pcm_substream *substream,
 		codec_params = *params;
 
 		/* fixup params based on TDM slot masks */
-		if (codec_dai->tx_mask)
+		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
+		    codec_dai->tx_mask)
 			soc_pcm_codec_params_fixup(&codec_params,
 						   codec_dai->tx_mask);
-		if (codec_dai->rx_mask)
+
+		if (substream->stream == SNDRV_PCM_STREAM_CAPTURE &&
+		    codec_dai->rx_mask)
 			soc_pcm_codec_params_fixup(&codec_params,
 						   codec_dai->rx_mask);
 
-- 
2.14.1