ASoC: hdmi-codec: remove reference to the current substream

If the hdmi-codec is on a codec-to-codec link, the substream pointer
it receives is completely made up by snd_soc_dai_link_event().
The pointer will be different between startup() and shutdown().

The hdmi-codec complains when this happens even if it is not really a
problem. The current_substream pointer is not used for anything useful
apart from getting the exclusive ownership of the device.

Remove current_substream pointer and replace the exclusive locking
mechanism with a simple variable and some atomic operations.

Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/hdmi-codec.c

@@ -280,11 +280,10 @@ struct hdmi_codec_priv {
 	struct hdmi_codec_pdata hcd;
 	struct snd_soc_dai_driver *daidrv;
 	struct hdmi_codec_daifmt daifmt[2];
-	struct mutex current_stream_lock;
-	struct snd_pcm_substream *current_stream;
 	uint8_t eld[MAX_ELD_BYTES];
 	struct snd_pcm_chmap *chmap_info;
 	unsigned int chmap_idx;
+	unsigned long busy;
 };
 
 static const struct snd_soc_dapm_widget hdmi_widgets[] = {
@@ -392,42 +391,22 @@ static int hdmi_codec_chmap_ctl_get(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
-static int hdmi_codec_new_stream(struct snd_pcm_substream *substream,
-				 struct snd_soc_dai *dai)
-{
-	struct hdmi_codec_priv *hcp = snd_soc_dai_get_drvdata(dai);
-	int ret = 0;
-
-	mutex_lock(&hcp->current_stream_lock);
-	if (!hcp->current_stream) {
-		hcp->current_stream = substream;
-	} else if (hcp->current_stream != substream) {
-		dev_err(dai->dev, "Only one simultaneous stream supported!\n");
-		ret = -EINVAL;
-	}
-	mutex_unlock(&hcp->current_stream_lock);
-
-	return ret;
-}
-
 static int hdmi_codec_startup(struct snd_pcm_substream *substream,
 			      struct snd_soc_dai *dai)
 {
 	struct hdmi_codec_priv *hcp = snd_soc_dai_get_drvdata(dai);
 	int ret = 0;
 
-	ret = hdmi_codec_new_stream(substream, dai);
-	if (ret)
-		return ret;
+	ret = test_and_set_bit(0, &hcp->busy);
+	if (ret) {
+		dev_err(dai->dev, "Only one simultaneous stream supported!\n");
+		return -EINVAL;
+	}
 
 	if (hcp->hcd.ops->audio_startup) {
 		ret = hcp->hcd.ops->audio_startup(dai->dev->parent, hcp->hcd.data);
-		if (ret) {
-			mutex_lock(&hcp->current_stream_lock);
-			hcp->current_stream = NULL;
-			mutex_unlock(&hcp->current_stream_lock);
-			return ret;
-		}
+		if (ret)
+			goto err;
 	}
 
 	if (hcp->hcd.ops->get_eld) {
@@ -437,32 +416,29 @@ static int hdmi_codec_startup(struct snd_pcm_substream *substream,
 		if (!ret) {
 			ret = snd_pcm_hw_constraint_eld(substream->runtime,
 							hcp->eld);
-			if (ret) {
-				mutex_lock(&hcp->current_stream_lock);
-				hcp->current_stream = NULL;
-				mutex_unlock(&hcp->current_stream_lock);
-				return ret;
-			}
+			if (ret)
+				goto err;
 		}
 		/* Select chmap supported */
 		hdmi_codec_eld_chmap(hcp);
 	}
 	return 0;
+
+err:
+	/* Release the exclusive lock on error */
+	clear_bit(0, &hcp->busy);
+	return ret;
 }
 
 static void hdmi_codec_shutdown(struct snd_pcm_substream *substream,
 				struct snd_soc_dai *dai)
 {
 	struct hdmi_codec_priv *hcp = snd_soc_dai_get_drvdata(dai);
 
-	WARN_ON(hcp->current_stream != substream);
-
 	hcp->chmap_idx = HDMI_CODEC_CHMAP_IDX_UNKNOWN;
 	hcp->hcd.ops->audio_shutdown(dai->dev->parent, hcp->hcd.data);
 
-	mutex_lock(&hcp->current_stream_lock);
-	hcp->current_stream = NULL;
-	mutex_unlock(&hcp->current_stream_lock);
+	clear_bit(0, &hcp->busy);
 }
 
 static int hdmi_codec_hw_params(struct snd_pcm_substream *substream,
@@ -761,8 +737,6 @@ static int hdmi_codec_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	hcp->hcd = *hcd;
-	mutex_init(&hcp->current_stream_lock);
-
 	hcp->daidrv = devm_kcalloc(dev, dai_count, sizeof(*hcp->daidrv),
 				   GFP_KERNEL);
 	if (!hcp->daidrv)