ASoC: create pcm for codec2codec links as well

At the moment, codec to codec links uses an ephemeral variable for
the struct snd_pcm_substream. Also the struct snd_soc_pcm_runtime
does not have real struct snd_pcm.

This might a problem if the functions used by a codec on codec to
codec link expect these structures to exist, and keep on existing
during the life of the codec.

For example, it is the case of the hdmi-codec, which uses
snd_pcm_add_chmap_ctls(). For the controls to works, the pcm and
substream must to exist.

This change is first step, it create pcm (and substreams) for codec
to codec links, in the same way as dpcm backend links.
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20190725165949.29699-5-jbrunet@baylibre.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-core.c

@@ -447,16 +447,6 @@ static void snd_soc_flush_all_delayed_work(struct snd_soc_card *card)
 		flush_delayed_work(&rtd->delayed_work);
 }
 
-static void codec2codec_close_delayed_work(struct work_struct *work)
-{
-	/*
-	 * Currently nothing to do for c2c links
-	 * Since c2c links are internal nodes in the DAPM graph and
-	 * don't interface with the outside world or application layer
-	 * we don't have to do any special handling on close.
-	 */
-}
-
 #ifdef CONFIG_PM_SLEEP
 /* powers down audio subsystem for suspend */
 int snd_soc_suspend(struct device *dev)
@@ -1555,7 +1545,6 @@ static int soc_probe_link_dais(struct snd_soc_card *card,
 		return ret;
 	}
 
-	if (!dai_link->params) {
 	/* create the pcm */
 	ret = soc_new_pcm(rtd, num);
 	if (ret < 0) {
@@ -1568,14 +1557,7 @@ static int soc_probe_link_dais(struct snd_soc_card *card,
 		return ret;
 	ret = soc_link_dai_pcm_new(rtd->codec_dais,
 				   rtd->num_codecs, rtd);
-		if (ret < 0)
 	return ret;
-	} else {
-		INIT_DELAYED_WORK(&rtd->delayed_work,
-				  codec2codec_close_delayed_work);
-	}
-
-	return 0;
 }
 
 static int soc_bind_aux_dev(struct snd_soc_card *card, int num)

sound/soc/soc-pcm.c

@@ -678,6 +678,16 @@ static void close_delayed_work(struct work_struct *work)
 	mutex_unlock(&rtd->pcm_mutex);
 }
 
+static void codec2codec_close_delayed_work(struct work_struct *work)
+{
+	/*
+	 * Currently nothing to do for c2c links
+	 * Since c2c links are internal nodes in the DAPM graph and
+	 * don't interface with the outside world or application layer
+	 * we don't have to do any special handling on close.
+	 */
+}
+
 /*
  * Called by ALSA when a PCM substream is closed. Private data can be
  * freed here. The cpu DAI, codec DAI, machine and components are also
@@ -3011,6 +3021,12 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 		playback = rtd->dai_link->dpcm_playback;
 		capture = rtd->dai_link->dpcm_capture;
 	} else {
+		/* Adapt stream for codec2codec links */
+		struct snd_soc_pcm_stream *cpu_capture = rtd->dai_link->params ?
+			&cpu_dai->driver->playback : &cpu_dai->driver->capture;
+		struct snd_soc_pcm_stream *cpu_playback = rtd->dai_link->params ?
+			&cpu_dai->driver->capture : &cpu_dai->driver->playback;
+
 		for_each_rtd_codec_dai(rtd, i, codec_dai) {
 			if (snd_soc_dai_stream_valid(codec_dai, SNDRV_PCM_STREAM_PLAYBACK) &&
 			    snd_soc_dai_stream_valid(cpu_dai,   SNDRV_PCM_STREAM_PLAYBACK))
@@ -3019,6 +3035,9 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 			    snd_soc_dai_stream_valid(cpu_dai,   SNDRV_PCM_STREAM_CAPTURE))
 				capture = 1;
 		}
+
+		capture = capture && cpu_capture->channels_min;
+		playback = playback && cpu_playback->channels_min;
 	}
 
 	if (rtd->dai_link->playback_only) {
@@ -3032,7 +3051,13 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 	}
 
 	/* create the PCM */
-	if (rtd->dai_link->no_pcm) {
+	if (rtd->dai_link->params) {
+		snprintf(new_name, sizeof(new_name), "codec2codec(%s)",
+			 rtd->dai_link->stream_name);
+
+		ret = snd_pcm_new_internal(rtd->card->snd_card, new_name, num,
+					   playback, capture, &pcm);
+	} else if (rtd->dai_link->no_pcm) {
 		snprintf(new_name, sizeof(new_name), "(%s)",
 			rtd->dai_link->stream_name);
 
@@ -3059,13 +3084,17 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 	dev_dbg(rtd->card->dev, "ASoC: registered pcm #%d %s\n",num, new_name);
 
 	/* DAPM dai link stream work */
+	if (rtd->dai_link->params)
+		INIT_DELAYED_WORK(&rtd->delayed_work,
+				  codec2codec_close_delayed_work);
+	else
 		INIT_DELAYED_WORK(&rtd->delayed_work, close_delayed_work);
 
 	pcm->nonatomic = rtd->dai_link->nonatomic;
 	rtd->pcm = pcm;
 	pcm->private_data = rtd;
 
-	if (rtd->dai_link->no_pcm) {
+	if (rtd->dai_link->no_pcm || rtd->dai_link->params) {
 		if (playback)
 			pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream->private_data = rtd;
 		if (capture)