[alsa-devel] [PATCH v2] ASoC: hdmi-codec: re-introduce mutex locking again

[Jerome Brunet]

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.

This change is not about functionality or efficiency. It is done with
the hope that it help maintainability in the future.

Suggested-by: Mark Brown <broonie at kernel.org>
Signed-off-by: Jerome Brunet <jbrunet at baylibre.com>
---
 sound/soc/codecs/hdmi-codec.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index f8b5b960e597..543363102d03 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;
 };
@@ -390,9 +391,10 @@ 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;
 	}
 
@@ -405,21 +407,21 @@ static int hdmi_codec_startup(struct snd_pcm_substream *substream,
 	if (hcp->hcd.ops->get_eld) {
 		ret = hcp->hcd.ops->get_eld(dai->dev->parent, hcp->hcd.data,
 					    hcp->eld, sizeof(hcp->eld));
+		if (ret)
+			goto err;
+
+		ret = snd_pcm_hw_constraint_eld(substream->runtime, hcp->eld);
+		if (ret)
+			goto err;
 
-		if (!ret) {
-			ret = snd_pcm_hw_constraint_eld(substream->runtime,
-							hcp->eld);
-			if (ret)
-				goto err;
-		}
 		/* Select chmap supported */
 		hdmi_codec_eld_chmap(hcp);
 	}
-	return 0;
+
+	hcp->busy = true;
 
 err:
-	/* Release the exclusive lock on error */
-	clear_bit(0, &hcp->busy);
+	mutex_unlock(&hcp->lock);
 	return ret;
 }
 
@@ -431,7 +433,9 @@ 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 +815,8 @@ 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;
-- 
2.23.0