ASoC: Intel: avs: Store pointer to link_stream in dma_data

While the HDAudio codec driver expectations must be met - store valid
pointer to HDAudio LINK stream in substream->runtime->private_data - the
code is more readable and easier to maintain if dma_data stores pointers
to both HOST and LINK stream.

DAI BE operations can refer to the LINK stream with data->link_stream,
similarly to how DAI FE operations access the HOST stream with
data->host_stream.
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20240426095733.3946951-8-cezary.rojewski@intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/avs/pcm.c

@@ -23,13 +23,12 @@ struct avs_dma_data {
 	struct avs_tplg_path_template *template;
 	struct avs_path *path;
 	struct avs_dev *adev;
-	/*
-	 * link stream is stored within substream's runtime
-	 * private_data to fulfill the needs of codec BE path
-	 *
-	 * host stream assigned
-	 */
+
+	/* LINK-stream utilized in BE operations while HOST in FE ones. */
+	union {
+		struct hdac_ext_stream *link_stream;
 		struct hdac_ext_stream *host_stream;
+	};
 
 	struct snd_pcm_substream *substream;
 };
@@ -263,6 +262,7 @@ static int avs_dai_hda_be_startup(struct snd_pcm_substream *substream, struct sn
 {
 	struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
 	struct hdac_ext_stream *link_stream;
+	struct avs_dma_data *data;
 	struct hda_codec *codec;
 	int ret;
 
@@ -278,18 +278,18 @@ static int avs_dai_hda_be_startup(struct snd_pcm_substream *substream, struct sn
 		return -EBUSY;
 	}
 
+	data = snd_soc_dai_get_dma_data(dai, substream);
+	data->link_stream = link_stream;
 	substream->runtime->private_data = link_stream;
 	return 0;
 }
 
 static void avs_dai_hda_be_shutdown(struct snd_pcm_substream *substream, struct snd_soc_dai *dai)
 {
-	struct hdac_ext_stream *link_stream;
+	struct avs_dma_data *data = snd_soc_dai_get_dma_data(dai, substream);
 
-	link_stream = substream->runtime->private_data;
-	snd_hdac_ext_stream_release(link_stream, HDAC_EXT_STREAM_TYPE_LINK);
+	snd_hdac_ext_stream_release(data->link_stream, HDAC_EXT_STREAM_TYPE_LINK);
 	substream->runtime->private_data = NULL;
-
 	avs_dai_shutdown(substream, dai);
 }
 
@@ -297,16 +297,13 @@ static int avs_dai_hda_be_hw_params(struct snd_pcm_substream *substream,
 				    struct snd_pcm_hw_params *hw_params, struct snd_soc_dai *dai)
 {
 	struct avs_dma_data *data;
-	struct hdac_ext_stream *link_stream;
 
 	data = snd_soc_dai_get_dma_data(dai, substream);
 	if (data->path)
 		return 0;
 
-	link_stream = substream->runtime->private_data;
-
 	return avs_dai_be_hw_params(substream, hw_params, dai,
-				    hdac_stream(link_stream)->stream_tag - 1);
+				    hdac_stream(data->link_stream)->stream_tag - 1);
 }
 
 static int avs_dai_hda_be_hw_free(struct snd_pcm_substream *substream, struct snd_soc_dai *dai)
@@ -323,7 +320,7 @@ static int avs_dai_hda_be_hw_free(struct snd_pcm_substream *substream, struct sn
 	if (!data->path)
 		return 0;
 
-	link_stream = substream->runtime->private_data;
+	link_stream = data->link_stream;
 	link_stream->link_prepared = false;
 	avs_path_free(data->path);
 	data->path = NULL;
@@ -347,13 +344,16 @@ static int avs_dai_hda_be_prepare(struct snd_pcm_substream *substream, struct sn
 	struct snd_soc_pcm_stream *stream_info;
 	struct hdac_ext_stream *link_stream;
 	struct hdac_ext_link *link;
+	struct avs_dma_data *data;
 	struct hda_codec *codec;
 	struct hdac_bus *bus;
 	unsigned int format_val;
 	unsigned int bits;
 	int ret;
 
-	link_stream = runtime->private_data;
+	data = snd_soc_dai_get_dma_data(dai, substream);
+	link_stream = data->link_stream;
+
 	if (link_stream->link_prepared)
 		return 0;
 
@@ -387,14 +387,12 @@ static int avs_dai_hda_be_trigger(struct snd_pcm_substream *substream, int cmd,
 				  struct snd_soc_dai *dai)
 {
 	struct snd_soc_pcm_runtime *rtd = snd_soc_substream_to_rtd(substream);
-	struct hdac_ext_stream *link_stream;
 	struct avs_dma_data *data;
 	int ret = 0;
 
 	dev_dbg(dai->dev, "entry %s cmd=%d\n", __func__, cmd);
 
 	data = snd_soc_dai_get_dma_data(dai, substream);
-	link_stream = substream->runtime->private_data;
 
 	switch (cmd) {
 	case SNDRV_PCM_TRIGGER_RESUME:
@@ -403,7 +401,7 @@ static int avs_dai_hda_be_trigger(struct snd_pcm_substream *substream, int cmd,
 		fallthrough;
 	case SNDRV_PCM_TRIGGER_START:
 	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
-		snd_hdac_ext_stream_start(link_stream);
+		snd_hdac_ext_stream_start(data->link_stream);
 
 		ret = avs_path_pause(data->path);
 		if (ret < 0) {
@@ -426,7 +424,7 @@ static int avs_dai_hda_be_trigger(struct snd_pcm_substream *substream, int cmd,
 		if (ret < 0)
 			dev_err(dai->dev, "pause BE path failed: %d\n", ret);
 
-		snd_hdac_ext_stream_clear(link_stream);
+		snd_hdac_ext_stream_clear(data->link_stream);
 
 		ret = avs_path_reset(data->path);
 		if (ret < 0)