[PATCH] ASoC: hdmi-codec: re-introduce mutex locking

[Jerome Brunet]

Replace the bit atomic operations by a mutex to ensure only one dai
at a time is active on the hdmi codec.

This is a follow up on change:
3fcf94ef4d41 ("ASoC: hdmi-codec: remove reference to the current substream")

Suggested-by: Mark Brown <broo...@kernel.org>
Signed-off-by: Jerome Brunet <jbru...@baylibre.com>
---
 sound/soc/codecs/hdmi-codec.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/sound/soc/codecs/hdmi-codec.c b/sound/soc/codecs/hdmi-codec.c
index 90a892766625..6a0cc8d7e141 100644
--- a/sound/soc/codecs/hdmi-codec.c
+++ b/sound/soc/codecs/hdmi-codec.c
@@ -281,7 +281,7 @@ 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;
 };
 
 static const struct snd_soc_dapm_widget hdmi_widgets[] = {
@@ -395,8 +395,8 @@ 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) {
+       ret = mutex_trylock(&hcp->lock);
+       if (!ret) {
                dev_err(dai->dev, "Only one simultaneous stream supported!\n");
                return -EINVAL;
        }
@@ -424,7 +424,7 @@ static int hdmi_codec_startup(struct snd_pcm_substream 
*substream,
 
 err:
        /* Release the exclusive lock on error */
-       clear_bit(0, &hcp->busy);
+       mutex_unlock(&hcp->lock);
        return ret;
 }
 
@@ -436,7 +436,7 @@ 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_unlock(&hcp->lock);
 }
 
 static int hdmi_codec_hw_params(struct snd_pcm_substream *substream,
@@ -773,6 +773,8 @@ 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;
-- 
2.20.1