linux-kernel - [PATCH v3] ASoC: soc-core.c: Prefer to return dai->driver->name in snd_soc_dai_name

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Date: Mon,  4 Mar 2024 16:21:28 +0900
From: Chancel Liu <chancel.liu@....com>
To: lgirdwood@...il.com,
	broonie@...nel.org,
	perex@...ex.cz,
	tiwai@...e.com,
	kuninori.morimoto.gx@...esas.com,
	linux-sound@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	alsa-devel@...a-project.org
Cc: Chancel Liu <chancel.liu@....com>
Subject: [PATCH v3] ASoC: soc-core.c: Prefer to return dai->driver->name in snd_soc_dai_name_get()

ASoC machine driver can use snd_soc_{of_}get_dlc() (A) to get DAI name
for dlc (snd_soc_dai_link_component). In this function call
dlc->dai_name is parsed via snd_soc_dai_name_get() (B).

(A)	int snd_soc_get_dlc(...)
	{
		...
(B)		dlc->dai_name = snd_soc_dai_name_get(dai);
		...
	}

(B) has a priority to return dai->name as dlc->dai_name. In most cases
card can probe successfully. However it has an issue that ASoC tries to
rebind card. Here is a simplified flow for example:

 |	a) Card probes successfully at first
 |	b) One of the component bound to this card is removed for some
 |	   reason the component->dev is released
 |	c) That component is re-registered
 v	d) ASoC calls snd_soc_try_rebind_card()

a) points dlc->dai_name to dai->name. b) releases all resource of the
old DAI. c) creates new DAI structure. In result d) can not use
dlc->dai_name to add new created DAI.

So it's reasonable that prefer to return dai->driver->name in
snd_soc_dai_name_get() because dai->driver is a pre-defined global
variable. Also update snd_soc_is_matching_dai() for alignment.

Signed-off-by: Chancel Liu <chancel.liu@....com>
---
changes in v2:
- update snd_soc_is_matching_dai() for alignment
changes in v3:
- resolve conflicts when applying patch, no others changed

 sound/soc/soc-core.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index 507cd3015ff4..1e94edba12eb 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -283,13 +283,13 @@ static int snd_soc_is_matching_dai(const struct snd_soc_dai_link_component *dlc,

 	/* see snd_soc_dai_name_get() */

-	if (strcmp(dlc->dai_name, dai->name) == 0)
-		return 1;
-
 	if (dai->driver->name &&
 	    strcmp(dlc->dai_name, dai->driver->name) == 0)
 		return 1;

+	if (strcmp(dlc->dai_name, dai->name) == 0)
+		return 1;
+
 	if (dai->component->name &&
 	    strcmp(dlc->dai_name, dai->component->name) == 0)
 		return 1;
@@ -300,12 +300,12 @@ static int snd_soc_is_matching_dai(const struct snd_soc_dai_link_component *dlc,
 const char *snd_soc_dai_name_get(struct snd_soc_dai *dai)
 {
 	/* see snd_soc_is_matching_dai() */
-	if (dai->name)
-		return dai->name;
-
 	if (dai->driver->name)
 		return dai->driver->name;

+	if (dai->name)
+		return dai->name;
+
 	if (dai->component->name)
 		return dai->component->name;

--
2.43.0