ASoC: dapm: Fix NULL pointer deference on CODEC to CODEC DAIs

Commit a655de80 ("ASoC: core: Allow topology to override
machine driver FE DAI link config.") caused soc_dai_hw_params to
be come dependent on the substream private_data being set with
a pointer to the snd_soc_pcm_runtime. Currently, CODEC to CODEC
links don't set this, which causes a NULL pointer dereference:

[<4069de54>] (soc_dai_hw_params) from
[<40694b68>] (snd_soc_dai_link_event+0x1a0/0x380)

Since the ASoC core in general assumes that the substream
private_data will be set to a pointer to the snd_soc_pcm_runtime,
update the CODEC to CODEC links to respect this.
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/soc-dapm.h

@@ -407,6 +407,7 @@ int snd_soc_dapm_new_dai_widgets(struct snd_soc_dapm_context *dapm,
 int snd_soc_dapm_link_dai_widgets(struct snd_soc_card *card);
 void snd_soc_dapm_connect_dai_link_widgets(struct snd_soc_card *card);
 int snd_soc_dapm_new_pcm(struct snd_soc_card *card,
+			 struct snd_soc_pcm_runtime *rtd,
 			 const struct snd_soc_pcm_stream *params,
 			 unsigned int num_params,
 			 struct snd_soc_dapm_widget *source,

sound/soc/soc-core.c

@@ -1447,7 +1447,7 @@ static int soc_link_dai_widgets(struct snd_soc_card *card,
 	sink = codec_dai->playback_widget;
 	source = cpu_dai->capture_widget;
 	if (sink && source) {
-		ret = snd_soc_dapm_new_pcm(card, dai_link->params,
+		ret = snd_soc_dapm_new_pcm(card, rtd, dai_link->params,
 					   dai_link->num_params,
 					   source, sink);
 		if (ret != 0) {
@@ -1460,7 +1460,7 @@ static int soc_link_dai_widgets(struct snd_soc_card *card,
 	sink = cpu_dai->playback_widget;
 	source = codec_dai->capture_widget;
 	if (sink && source) {
-		ret = snd_soc_dapm_new_pcm(card, dai_link->params,
+		ret = snd_soc_dapm_new_pcm(card, rtd, dai_link->params,
 					   dai_link->num_params,
 					   source, sink);
 		if (ret != 0) {

sound/soc/soc-dapm.c

@@ -3652,6 +3652,7 @@ static int snd_soc_dai_link_event(struct snd_soc_dapm_widget *w,
 {
 	struct snd_soc_dapm_path *source_p, *sink_p;
 	struct snd_soc_dai *source, *sink;
+	struct snd_soc_pcm_runtime *rtd = w->priv;
 	const struct snd_soc_pcm_stream *config = w->params + w->params_select;
 	struct snd_pcm_substream substream;
 	struct snd_pcm_hw_params *params = NULL;
@@ -3711,6 +3712,7 @@ static int snd_soc_dai_link_event(struct snd_soc_dapm_widget *w,
 		goto out;
 	}
 	substream.runtime = runtime;
+	substream.private_data = rtd;
 
 	switch (event) {
 	case SND_SOC_DAPM_PRE_PMU:
@@ -3895,6 +3897,7 @@ snd_soc_dapm_alloc_kcontrol(struct snd_soc_card *card,
 }
 
 int snd_soc_dapm_new_pcm(struct snd_soc_card *card,
+			 struct snd_soc_pcm_runtime *rtd,
 			 const struct snd_soc_pcm_stream *params,
 			 unsigned int num_params,
 			 struct snd_soc_dapm_widget *source,
@@ -3963,6 +3966,7 @@ int snd_soc_dapm_new_pcm(struct snd_soc_card *card,
 
 	w->params = params;
 	w->num_params = num_params;
+	w->priv = rtd;
 
 	ret = snd_soc_dapm_add_path(&card->dapm, source, w, NULL, NULL);
 	if (ret)