[PATCH 1/9] ASoC: apple: mca: Constrain channels according to TDM mask

[James Calligeros <jcalligeros99@gmail.com>]

From: Martin Povišer <povik+lin@cutebit.org>

We don't (and can't) configure the hardware correctly if the number of
channels exceeds the weight of the TDM mask. Report that constraint in
startup of FE.

Fixes: 3df5d0d97289 ("ASoC: apple: mca: Start new platform driver")
Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Signed-off-by: James Calligeros <jcalligeros99@gmail.com>
---
 sound/soc/apple/mca.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/sound/soc/apple/mca.c b/sound/soc/apple/mca.c
index b4f4696809dd231a64229114c5550bb5f237607f..5dd24ab90d0f052bb48f451cf009dc2e9128014d 100644
--- a/sound/soc/apple/mca.c
+++ b/sound/soc/apple/mca.c
@@ -464,6 +464,28 @@ static int mca_configure_serdes(struct mca_cluster *cl, int serdes_unit,
 	return -EINVAL;
 }
 
+static int mca_fe_startup(struct snd_pcm_substream *substream,
+			  struct snd_soc_dai *dai)
+{
+	struct mca_cluster *cl = mca_dai_to_cluster(dai);
+	unsigned int mask, nchannels;
+
+	if (cl->tdm_slots) {
+		if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+			mask = cl->tdm_tx_mask;
+		else
+			mask = cl->tdm_rx_mask;
+
+		nchannels = hweight32(mask);
+	} else {
+		nchannels = 2;
+	}
+
+	return snd_pcm_hw_constraint_minmax(substream->runtime,
+					    SNDRV_PCM_HW_PARAM_CHANNELS,
+					    1, nchannels);
+}
+
 static int mca_fe_set_tdm_slot(struct snd_soc_dai *dai, unsigned int tx_mask,
 			       unsigned int rx_mask, int slots, int slot_width)
 {
@@ -680,6 +702,7 @@ static int mca_fe_hw_params(struct snd_pcm_substream *substream,
 }
 
 static const struct snd_soc_dai_ops mca_fe_ops = {
+	.startup = mca_fe_startup,
 	.set_fmt = mca_fe_set_fmt,
 	.set_bclk_ratio = mca_set_bclk_ratio,
 	.set_tdm_slot = mca_fe_set_tdm_slot,

-- 
2.49.0