[alsa-devel] [PATCH] ASoC: AMD: Add delay before starting to capture

[Agrawal, Akshu]

On capture through dmic we observe a glitch at the start of record.
This is because we start capturing even before dmic is ready to send
out data. The glitch seen last for ~20msec.

Signed-off-by: Akshu Agrawal <akshu.agrawal at amd.com>
Signed-off-by: Daniel Kurtz <djkurtz at chromium.org>
---
 sound/soc/amd/acp-da7219-max98357a.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/sound/soc/amd/acp-da7219-max98357a.c b/sound/soc/amd/acp-da7219-max98357a.c
index a5daad9..72b1cf4 100644
--- a/sound/soc/amd/acp-da7219-max98357a.c
+++ b/sound/soc/amd/acp-da7219-max98357a.c
@@ -44,6 +44,8 @@
 
 #define CZ_PLAT_CLK 48000000
 #define DUAL_CHANNEL		2
+#define ADAU7002_DELAY_MS  20
+
 
 static struct snd_soc_jack cz_jack;
 static struct clk *da7219_dai_clk;
@@ -213,6 +215,7 @@ static int cz_dmic0_startup(struct snd_pcm_substream *substream)
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_soc_card *card = rtd->card;
 	struct acp_platform_info *machine = snd_soc_card_get_drvdata(card);
+	int ret;
 
 	/*
 	 * On this platform for PCM device we support stereo
@@ -225,7 +228,17 @@ static int cz_dmic0_startup(struct snd_pcm_substream *substream)
 				   &constraints_rates);
 
 	machine->cap_i2s_instance = I2S_BT_INSTANCE;
-	return da7219_clk_enable(substream);
+	ret = da7219_clk_enable(substream);
+	if (ret)
+		return ret;
+	/*
+	 * On some platforms, it takes ~20 msec for PDM DMICs and ADAU7002
+	 * to settle and start producing proper audio data.
+	 */
+	msleep(ADAU7002_DELAY_MS);
+	/* Delay in frames for 48Khz, 16bit, 2 channel */
+	runtime->delay = ADAU7002_DELAY_MS * 48;
+	return 0;
 }
 
 static int cz_dmic1_startup(struct snd_pcm_substream *substream)
@@ -234,6 +247,7 @@ static int cz_dmic1_startup(struct snd_pcm_substream *substream)
 	struct snd_soc_pcm_runtime *rtd = substream->private_data;
 	struct snd_soc_card *card = rtd->card;
 	struct acp_platform_info *machine = snd_soc_card_get_drvdata(card);
+	int ret;
 
 	/*
 	 * On this platform for PCM device we support stereo
@@ -247,7 +261,17 @@ static int cz_dmic1_startup(struct snd_pcm_substream *substream)
 
 	machine->cap_i2s_instance = I2S_SP_INSTANCE;
 	machine->capture_channel = CAP_CHANNEL0;
-	return da7219_clk_enable(substream);
+	ret = da7219_clk_enable(substream);
+	if (ret)
+		return ret;
+	/*
+	 * On some platforms, it takes ~20 msec for PDM DMICs and ADAU7002
+	 * to settle and start producing proper audio data.
+	 */
+	msleep(ADAU7002_DELAY_MS);
+	/* Delay in frames for 48Khz, 16bit, 2 channel */
+	runtime->delay = ADAU7002_DELAY_MS * 48;
+	return 0;
 }
 
 static void cz_dmic_shutdown(struct snd_pcm_substream *substream)
-- 
1.9.1