lsm_client: add support to perform channel mixing

With pre-processing applied, it is possible that the processed
number of channels could be different than the number of channels
that voice wakeup can run with. In such cases, the channel mixer
should be setup to downmix the channel. For voice wakeup to detect
keywords properly, preprocessed channels cannot be mixed hence
the channel mixer is always setup with unity co-efficients or 0
to either select or drop the channel. In this case the channel mixer
acts more like an channel selector.

Change-Id: I79b578b56ad5484e27f433404a5371540618a2ae
Signed-off-by: Bhalchandra Gajare <[email protected]>

asoc/msm-lsm-client.c

@@ -2263,6 +2263,77 @@ static int msm_lsm_open(struct snd_pcm_substream *substream)
 	return 0;
 }
 
+static int msm_lsm_send_ch_mix_config(struct snd_pcm_substream *substream)
+{
+	struct snd_pcm_runtime *runtime = substream->runtime;
+	struct lsm_priv *prtd = runtime->private_data;
+	struct snd_soc_pcm_runtime *rtd;
+	struct lsm_hw_params *in_params;
+	int pp_ch_cnt;
+	int *ch_wght_coeff;
+	int ret = 0, i, idx;
+
+	/*
+	 * The output channels from channel mixer is the input to LSM (stream)
+	 * side and is read from in_params->num_chs.
+	 *
+	 * The input channels to channel mixer are the output channels from
+	 * the device side (routing) and is obtained by reading the
+	 * pp_ch_cnt.
+	 *
+	 * For LSM to be functional, only unity channel mixing is allowed.
+	 */
+
+	in_params = &prtd->lsm_client->in_hw_params;
+	rtd = prtd->substream->private_data;
+	pp_ch_cnt = msm_pcm_routing_get_pp_ch_cnt(rtd->dai_link->id,
+						  SESSION_TYPE_TX);
+	if (pp_ch_cnt < 0 ||
+	    pp_ch_cnt > LSM_V3P0_MAX_NUM_CHANNELS ||
+	     in_params->num_chs > LSM_V3P0_MAX_NUM_CHANNELS) {
+		dev_err(rtd->dev,
+			"%s: invalid ch cnt, pp_ch_cnt %d in_ch_cnt %d\n",
+			__func__, pp_ch_cnt, in_params->num_chs);
+		return -EINVAL;
+	}
+
+	if (!pp_ch_cnt ||
+	    (pp_ch_cnt == in_params->num_chs)) {
+		dev_dbg(rtd->dev,
+			"%s: Skip ch mixing, pp_ch_cnt %d in_ch_cnt %d\n",
+			__func__, pp_ch_cnt, in_params->num_chs);
+		return 0;
+	}
+
+	ch_wght_coeff = kzalloc(in_params->num_chs * pp_ch_cnt * sizeof(int),
+				GFP_KERNEL);
+	if (!ch_wght_coeff)
+		return -ENOMEM;
+
+	/*
+	 * channel weight co-efficients is a m X n array, where
+	 * m = number of input channels to ch mixer (pp_ch_cnt)
+	 * n = number of output channels from ch mixer (in_params->num_chs)
+	 */
+	for (i = 0; i < in_params->num_chs; i++) {
+		idx = (i * pp_ch_cnt) + i;
+		ch_wght_coeff[idx] = 1;
+	}
+
+	ret = msm_pcm_routing_send_chmix_cfg(rtd->dai_link->id,
+					     pp_ch_cnt, in_params->num_chs,
+					     ch_wght_coeff,
+					     SESSION_TYPE_TX, STREAM_TYPE_LSM);
+	if (ret)
+		dev_err(rtd->dev,
+			"%s: Failed to configure channel mixer err %d\n",
+			__func__, ret);
+
+	kfree(ch_wght_coeff);
+
+	return ret;
+}
+
 static int msm_lsm_prepare(struct snd_pcm_substream *substream)
 {
 	struct snd_pcm_runtime *runtime = substream->runtime;
@@ -2300,6 +2371,13 @@ static int msm_lsm_prepare(struct snd_pcm_substream *substream)
 					__func__, ret);
 			return ret;
 		}
+
+		ret = msm_lsm_send_ch_mix_config(substream);
+		if (ret) {
+			msm_pcm_routing_dereg_phy_stream(rtd->dai_link->id,
+					SNDRV_PCM_STREAM_CAPTURE);
+			return ret;
+		}
 	}
 
 	prtd->lsm_client->session_state = RUNNING;