[PATCH 4/4] ASoC: wm8524: Delay some time to follow power up sequency

[Chancel Liu]

The recommended power sequence needs to be followed to ensure the best
performance. After MCLK, BCLK and MUTE=1 are ready, this device has to
wait some time before ready to output audio. Otherwise the beginning
data may be lost. For more details about the timing constraints, please
refer to WTN0302 on https://www.cirrus.com/products/wm8524/

Signed-off-by: Chancel Liu <chancel.liu@xxxxxxx>
---
 sound/soc/codecs/wm8524.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/sound/soc/codecs/wm8524.c b/sound/soc/codecs/wm8524.c
index 8f2130e05b32..f61967b66c3b 100644
--- a/sound/soc/codecs/wm8524.c
+++ b/sound/soc/codecs/wm8524.c
@@ -21,6 +21,7 @@
 #include <sound/soc.h>
 #include <sound/initval.h>
 
+#define WM8524_POWER_UP_DELAY_MS 100
 #define WM8524_NUM_RATES 7
 
 /* codec private data */
@@ -29,6 +30,7 @@ struct wm8524_priv {
 	unsigned int sysclk;
 	unsigned int rate_constraint_list[WM8524_NUM_RATES];
 	struct snd_pcm_hw_constraint_list rate_constraint;
+	unsigned int power_up_delay;
 };
 
 
@@ -157,6 +159,28 @@ static int wm8524_mute_stream(struct snd_soc_dai *dai, int mute, int stream)
 	return 0;
 }
 
+static int wm8524_trigger(struct snd_pcm_substream *substream, int cmd,
+			  struct snd_soc_dai *dai)
+{
+	struct wm8524_priv *wm8524 = snd_soc_dai_get_drvdata(dai);
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		mdelay(wm8524->power_up_delay);
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+};
+
 #define WM8524_RATES SNDRV_PCM_RATE_8000_192000
 
 #define WM8524_FORMATS (SNDRV_PCM_FMTBIT_S16_LE |\
@@ -169,6 +193,7 @@ static const struct snd_soc_dai_ops wm8524_dai_ops = {
 	.set_sysclk	= wm8524_set_dai_sysclk,
 	.set_fmt	= wm8524_set_fmt,
 	.mute_stream	= wm8524_mute_stream,
+	.trigger	= wm8524_trigger,
 };
 
 static struct snd_soc_dai_driver wm8524_dai = {
@@ -213,6 +238,7 @@ MODULE_DEVICE_TABLE(of, wm8524_of_match);
 
 static int wm8524_codec_probe(struct platform_device *pdev)
 {
+	struct device_node *np = pdev->dev.of_node;
 	struct wm8524_priv *wm8524;
 	int ret;
 
@@ -230,6 +256,9 @@ static int wm8524_codec_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	wm8524->power_up_delay = WM8524_POWER_UP_DELAY_MS;
+	of_property_read_u32(np, "wlf,power-up-delay-ms", &wm8524->power_up_delay);
+
 	ret = devm_snd_soc_register_component(&pdev->dev,
 			&soc_component_dev_wm8524, &wm8524_dai, 1);
 	if (ret < 0)
-- 
2.25.1