linux-kernel - [PATCH 2/2] ASoC: hdmi-codec: re-introduce mutex locking again

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Date:   Wed, 23 Oct 2019 18:12:03 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Mark Brown <broonie@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>
Cc:     Jerome Brunet <jbrunet@...libre.com>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org,
        Russell King <rmk+kernel@...linux.org.uk>
Subject: [PATCH 2/2] ASoC: hdmi-codec: re-introduce mutex locking again

The dai codec needs to ensure that on one dai is used at any time.
This is currently protected by bit atomic operation. With this change,
it done with a mutex instead.

Suggested-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
---
 sound/soc/codecs/hdmi-codec.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index f8b5b960e597..56f6373d7927 100644
--- a/sound/soc/codecs/hdmi-codec.c
+++ b/sound/soc/codecs/hdmi-codec.c
@@ -274,7 +274,8 @@ struct hdmi_codec_priv {
 	uint8_t eld[MAX_ELD_BYTES];
 	struct snd_pcm_chmap *chmap_info;
 	unsigned int chmap_idx;
-	unsigned long busy;
+	struct mutex lock;
+	bool busy;
 	struct snd_soc_jack *jack;
 	unsigned int jack_status;
 };
@@ -390,12 +391,15 @@ static int hdmi_codec_startup(struct snd_pcm_substream *substream,
 	struct hdmi_codec_priv *hcp = snd_soc_dai_get_drvdata(dai);
 	int ret = 0;
 
-	ret = test_and_set_bit(0, &hcp->busy);
-	if (ret) {
+	mutex_lock(&hcp->lock);
+	if (hcp->busy) {
 		dev_err(dai->dev, "Only one simultaneous stream supported!\n");
+		mutex_unlock(&hcp->lock);
 		return -EINVAL;
 	}
 
+	hcp->busy = true;
+
 	if (hcp->hcd.ops->audio_startup) {
 		ret = hcp->hcd.ops->audio_startup(dai->dev->parent, hcp->hcd.data);
 		if (ret)
@@ -415,11 +419,12 @@ static int hdmi_codec_startup(struct snd_pcm_substream *substream,
 		/* Select chmap supported */
 		hdmi_codec_eld_chmap(hcp);
 	}
-	return 0;
 
 err:
-	/* Release the exclusive lock on error */
-	clear_bit(0, &hcp->busy);
+	if (ret)
+		hcp->busy = false;
+
+	mutex_unlock(&hcp->lock);
 	return ret;
 }
 
@@ -431,7 +436,9 @@ static void hdmi_codec_shutdown(struct snd_pcm_substream *substream,
 	hcp->chmap_idx = HDMI_CODEC_CHMAP_IDX_UNKNOWN;
 	hcp->hcd.ops->audio_shutdown(dai->dev->parent, hcp->hcd.data);
 
-	clear_bit(0, &hcp->busy);
+	mutex_lock(&hcp->lock);
+	hcp->busy = false;
+	mutex_unlock(&hcp->lock);
 }
 
 static int hdmi_codec_hw_params(struct snd_pcm_substream *substream,
@@ -811,6 +818,8 @@ static int hdmi_codec_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	hcp->hcd = *hcd;
+	mutex_init(&hcp->lock);
+
 	daidrv = devm_kcalloc(dev, dai_count, sizeof(*daidrv), GFP_KERNEL);
 	if (!daidrv)
 		return -ENOMEM;
-- 
2.21.0