1 files changed, 22 insertions, 5 deletions

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index 10ae75e19d99..a9822c7bbb0b 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -629,13 +629,29 @@ static int mcasp_common_hw_param(struct davinci_mcasp *mcasp, int stream,
         return 0;
 }
 
-static int mcasp_i2s_hw_param(struct davinci_mcasp *mcasp, int stream)
+static int mcasp_i2s_hw_param(struct davinci_mcasp *mcasp, int stream,
+                              int channels)
 {
         int i, active_slots;
+        int total_slots;
+        int active_serializers;
         u32 mask = 0;
         u32 busel = 0;
 
-        active_slots = mcasp->tdm_slots;
+        total_slots = mcasp->tdm_slots;
+
+        /*
+         * If more than one serializer is needed, then use them with
+         * their specified tdm_slots count. Otherwise, one serializer
+         * can cope with the transaction using as many slots as channels
+         * in the stream, requires channels symmetry
+         */
+        active_serializers = (channels + total_slots - 1) / total_slots;
+        if (active_serializers == 1)
+                active_slots = channels;
+        else
+                active_slots = total_slots;
+
         for (i = 0; i < active_slots; i++)
                 mask |= (1 << i);
 
@@ -647,12 +663,12 @@ static int mcasp_i2s_hw_param(struct davinci_mcasp *mcasp, int stream)
         mcasp_set_reg(mcasp, DAVINCI_MCASP_TXTDM_REG, mask);
         mcasp_set_bits(mcasp, DAVINCI_MCASP_TXFMT_REG, busel | TXORD);
         mcasp_mod_bits(mcasp, DAVINCI_MCASP_TXFMCTL_REG,
-                       FSXMOD(active_slots), FSXMOD(0x1FF));
+                       FSXMOD(total_slots), FSXMOD(0x1FF));
 
         mcasp_set_reg(mcasp, DAVINCI_MCASP_RXTDM_REG, mask);
         mcasp_set_bits(mcasp, DAVINCI_MCASP_RXFMT_REG, busel | RXORD);
         mcasp_mod_bits(mcasp, DAVINCI_MCASP_RXFMCTL_REG,
-                       FSRMOD(active_slots), FSRMOD(0x1FF));
+                       FSRMOD(total_slots), FSRMOD(0x1FF));
 
         return 0;
 }
@@ -766,7 +782,8 @@ static int davinci_mcasp_hw_params(struct snd_pcm_substream *substream,
         if (mcasp->op_mode == DAVINCI_MCASP_DIT_MODE)
                 ret = mcasp_dit_hw_param(mcasp, params_rate(params));
         else
-                ret = mcasp_i2s_hw_param(mcasp, substream->stream);
+                ret = mcasp_i2s_hw_param(mcasp, substream->stream,
+                                         channels);
 
         if (ret)
                 return ret;