Re: [alsa-devel] [PATCH v1 3/3] ASoC: soc-core: fix platform name vs. of_node assignement

[Kuninori Morimoto]

Hi Jon

> I have been looking at this again recently. I see this issue occurring
> all the time when the sound drivers are built as kernel modules and
> probing the sound card is deferred until the codec driver has been loaded.
> 
> Commit daecf46ee0e5 ("ASoC: soc-core: use snd_soc_dai_link_component for
> platform") appears to introduce the problem because now we allocate the
> 'snd_soc_dai_link_component' structure for the platform we attempt to
> register the soundcard but we never clear the freed pointer on failure.
> Therefore, we only actually allocate it the first time. There is no easy
> way to clear this pointer for the memory allocated because this is done
> before the dai-links have been added to the list of dai-links for the
> soundcard.
> 
> I don't see an easy solution that will be 100% robust unless you do opt
> for copying all the dai-link info from the platform (but this is
> probably not a trivial fix).
> 
> Do you envision a fix any time soon, or should we be updating all the
> machine drivers to populate the platform snd_soc_dai_link_component so
> that it is handled by the machine drivers are not the core?

Thank you for pointing it.
Indeed it is mess.
I think coping info is nice idea,
but it is not easy so far, and it uses much memory...

I didn't test this, but can below patch solve your issue ?
I think same issue happen on codec side too, so it cares it too.

---------------
diff --git a/include/sound/soc.h b/include/sound/soc.h
index 8ec1de8..49ac5a8 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -985,6 +985,10 @@ struct snd_soc_dai_link {
 	/* Do not create a PCM for this DAI link (Backend link) */
 	unsigned int ignore:1;
 
+	/* allocated dai_link_comonent. These should be removed in the future */
+	unsigned int allocated_platform:1;
+	unsigned int allocated_codecs:1;
+
 	struct list_head list; /* DAI link list of the soc card */
 	struct snd_soc_dobj dobj; /* For topology */
 };
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 0462b3e..49ccea3 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -1023,6 +1023,25 @@ static void soc_remove_dai_links(struct snd_soc_card *card)
 	}
 }
 
+static void snd_soc_init_dai_link_component(struct snd_soc_card *card)
+{
+	struct snd_soc_dai_link *dai_link;
+	int i;
+
+	/*
+	 * FIXME
+	 *
+	 * this function should be removed in the future
+	 */
+	for_each_card_prelinks(card, i, dai_link) {
+		/* see snd_soc_init_platform */
+		if (dai_link->allocated_platform)
+			dai_link->platform = NULL;
+		if (dai_link->allocated_codecs)
+			dai_link->codecs = NULL;
+	}
+}
+
 static int snd_soc_init_platform(struct snd_soc_card *card,
 				 struct snd_soc_dai_link *dai_link)
 {
@@ -1042,6 +1061,8 @@ static int snd_soc_init_platform(struct snd_soc_card *card,
 			return -ENOMEM;
 
 		dai_link->platform	= platform;
+		dai_link->allocated_platform	= 1;
+
 		platform->name		= dai_link->platform_name;
 		platform->of_node	= dai_link->platform_of_node;
 		platform->dai_name	= NULL;
@@ -1069,6 +1090,8 @@ static int snd_soc_init_multicodec(struct snd_soc_card *card,
 		if (!dai_link->codecs)
 			return -ENOMEM;
 
+		dai_link->allocated_codecs = 1;
+
 		dai_link->codecs[0].name = dai_link->codec_name;
 		dai_link->codecs[0].of_node = dai_link->codec_of_node;
 		dai_link->codecs[0].dai_name = dai_link->codec_dai_name;
@@ -2739,6 +2762,8 @@ int snd_soc_register_card(struct snd_soc_card *card)
 	if (!card->name || !card->dev)
 		return -EINVAL;
 
+	snd_soc_init_dai_link_component(card);
+
 	for_each_card_prelinks(card, i, link) {
 
 		ret = soc_init_dai_link(card, link);
---------------


Best regards
---
Kuninori Morimoto