ASoC: davinci-mcasp: Place constraint on number of channels

In IIS (I2S, TDM, etc) mode the maximum number of allowed channels for
either direction can be:
number of serializers for the direction * tdm_slots.
This constraint applicable for the first stream, while consequent stream
should not have more channels then the first stream.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index 10c264738a0b..10ae75e19d99 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -90,6 +90,9 @@ struct davinci_mcasp {
 
         bool    dat_port;
 
+        /* Used for comstraint setting on the second stream */
+        u32     channels;
+
 #ifdef CONFIG_PM_SLEEP
         struct davinci_mcasp_context context;
 #endif
@@ -811,6 +814,9 @@ static int davinci_mcasp_hw_params(struct snd_pcm_substream *substream,
 
         davinci_config_channel_size(mcasp, word_length);
 
+        if (mcasp->op_mode == DAVINCI_MCASP_IIS_MODE)
+                mcasp->channels = channels;
+
         return 0;
 }
 
@@ -839,7 +845,61 @@ static int davinci_mcasp_trigger(struct snd_pcm_substream *substream,
         return ret;
 }
 
+static int davinci_mcasp_startup(struct snd_pcm_substream *substream,
+                                 struct snd_soc_dai *cpu_dai)
+{
+        struct davinci_mcasp *mcasp = snd_soc_dai_get_drvdata(cpu_dai);
+        u32 max_channels = 0;
+        int i, dir;
+
+        if (mcasp->op_mode == DAVINCI_MCASP_DIT_MODE)
+                return 0;
+
+        /*
+         * Limit the maximum allowed channels for the first stream:
+         * number of serializers for the direction * tdm slots per serializer
+         */
+        if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+                dir = TX_MODE;
+        else
+                dir = RX_MODE;
+
+        for (i = 0; i < mcasp->num_serializer; i++) {
+                if (mcasp->serial_dir[i] == dir)
+                        max_channels++;
+        }
+        max_channels *= mcasp->tdm_slots;
+        /*
+         * If the already active stream has less channels than the calculated
+         * limnit based on the seirializers * tdm_slots, we need to use that as
+         * a constraint for the second stream.
+         * Otherwise (first stream or less allowed channels) we use the
+         * calculated constraint.
+         */
+        if (mcasp->channels && mcasp->channels < max_channels)
+                max_channels = mcasp->channels;
+
+        snd_pcm_hw_constraint_minmax(substream->runtime,
+                                     SNDRV_PCM_HW_PARAM_CHANNELS,
+                                     2, max_channels);
+        return 0;
+}
+
+static void davinci_mcasp_shutdown(struct snd_pcm_substream *substream,
+                                   struct snd_soc_dai *cpu_dai)
+{
+        struct davinci_mcasp *mcasp = snd_soc_dai_get_drvdata(cpu_dai);
+
+        if (mcasp->op_mode == DAVINCI_MCASP_DIT_MODE)
+                return;
+
+        if (!cpu_dai->active)
+                mcasp->channels = 0;
+}
+
 static const struct snd_soc_dai_ops davinci_mcasp_dai_ops = {
+        .startup        = davinci_mcasp_startup,
+        .shutdown       = davinci_mcasp_shutdown,
         .trigger        = davinci_mcasp_trigger,
         .hw_params      = davinci_mcasp_hw_params,
         .set_fmt        = davinci_mcasp_set_dai_fmt,