ASoC: OMAP: Apply channel constrains to N810 machine driver

Prepare for upcoming McBSP DAI update adding support for mono links by
restricting number of channels to 2 in N810. This is due tlv320aic3x which
claims channels_min = 1 and playing pure mono audio over I2S would cause
it to be played only from left channel if both cpu and codec DAI's claim to
support mono.

Signed-off-by: Jarkko Nikula <jarkko.nikula@nokia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/sound/soc/omap/n810.c b/sound/soc/omap/n810.c
index d216b4f9e14e..18e2062e3a11 100644
--- a/sound/soc/omap/n810.c
+++ b/sound/soc/omap/n810.c
@@ -70,9 +70,13 @@ static void n810_ext_control(struct snd_soc_codec *codec)
 
 static int n810_startup(struct snd_pcm_substream *substream)
 {
+        struct snd_pcm_runtime *runtime = substream->runtime;
         struct snd_soc_pcm_runtime *rtd = substream->private_data;
         struct snd_soc_codec *codec = rtd->socdev->codec;
 
+        snd_pcm_hw_constraint_minmax(runtime,
+                                     SNDRV_PCM_HW_PARAM_CHANNELS, 2, 2);
+
         n810_ext_control(codec);
         return clk_enable(sys_clkout2);
 }