[alsa-devel] [PATCH 1/3] ASoC: core: Add card mutex locking subclasses

Liam Girdwood lrg at ti.com
Wed Mar 7 11:38:25 CET 2012

This is the first part of a change that is intended to improve
ASoC locking protection for DAPM and PCM operations.

This part of the series adds a mutex class for the soc_card mutex. The
SND_SOC_CARD_CLASS_INIT class is used for card initialisation only whilst the
SND_SOC_CARD_CLASS_PCM class is used for the forth coming Dynamic
PCM operations. The new mutex classes are required otherwise we will see a false
positive mutex deadlock warning between the card initialisation and the PCM
operations (something that would never deadlock in real life).

Signed-off-by: Liam Girdwood <lrg at ti.com>
 include/sound/soc.h  |    5 +++++
 sound/soc/soc-core.c |    2 +-
 2 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/include/sound/soc.h b/include/sound/soc.h
index 2ebf787..70de2f8 100644
--- a/include/sound/soc.h
+++ b/include/sound/soc.h
@@ -288,6 +288,11 @@ enum snd_soc_pcm_subclass {
+enum snd_soc_card_subclass {
 int snd_soc_codec_set_sysclk(struct snd_soc_codec *codec, int clk_id,
 			     int source, unsigned int freq, int dir);
 int snd_soc_codec_set_pll(struct snd_soc_codec *codec, int pll_id, int source,
diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
index c90bb01..acd0d93 100644
--- a/sound/soc/soc-core.c
+++ b/sound/soc/soc-core.c
@@ -1416,7 +1416,7 @@ static void snd_soc_instantiate_card(struct snd_soc_card *card)
 	struct snd_soc_dai_link *dai_link;
 	int ret, i, order;
-	mutex_lock(&card->mutex);
+	mutex_lock_nested(&card->mutex, SND_SOC_CARD_CLASS_INIT);
 	if (card->instantiated) {

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