ASoC: rk3399_gru_sound: fix recording pop at first attempt

Pop happens when mclk applied but dmic's own boot-time
Specify dmic delay times in dt to make sure
clocks are ready earlier than dmic working
Signed-off-by: NWonjoon Lee <woojoo.lee@samsung.com>
Signed-off-by: NXing Zheng <zhengxing@rock-chips.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/sound/rockchip,rk3399-gru-sound.txt

@@ -6,10 +6,17 @@ Required properties:
   connected to the codecs
 - rockchip,codec: The phandle of the MAX98357A/RT5514/DA7219 codecs
 
+Optional properties:
+- dmic-wakeup-delay-ms : specify delay time (ms) for DMIC ready.
+  If this option is specified, which means it's required dmic need
+  delay for DMIC to ready so that rt5514 can avoid recording before
+  DMIC send valid data
+
 Example:
 
 sound {
 	compatible = "rockchip,rk3399-gru-sound";
 	rockchip,cpu = <&i2s0>;
 	rockchip,codec = <&max98357a &rt5514 &da7219>;
+	dmic-wakeup-delay-ms = <20>;
 };

sound/soc/rockchip/rk3399_gru_sound.c

@@ -38,6 +38,8 @@
 
 #define SOUND_FS	256
 
+unsigned int rt5514_dmic_delay;
+
 static struct snd_soc_jack rockchip_sound_jack;
 
 static const struct snd_soc_dapm_widget rockchip_dapm_widgets[] = {
@@ -123,6 +125,9 @@ static int rockchip_sound_rt5514_hw_params(struct snd_pcm_substream *substream,
 		return ret;
 	}
 
+	/* Wait for DMIC stable */
+	msleep(rt5514_dmic_delay);
+
 	return 0;
 }
 
@@ -343,6 +348,15 @@ static int rockchip_sound_probe(struct platform_device *pdev)
 		return -ENODEV;
 	}
 
+	/* Set DMIC delay */
+	ret = device_property_read_u32(&pdev->dev, "dmic-delay",
+					&rt5514_dmic_delay);
+	if (ret) {
+		rt5514_dmic_delay = 0;
+		dev_dbg(&pdev->dev,
+			"no optional property 'dmic-delay' found, default: no delay\n");
+	}
+
 	rockchip_dailinks[DAILINK_RT5514_DSP].cpu_name = kstrdup_const(dev_name(dev), GFP_KERNEL);
 	rockchip_dailinks[DAILINK_RT5514_DSP].cpu_dai_name = kstrdup_const(dev_name(dev), GFP_KERNEL);
 	rockchip_dailinks[DAILINK_RT5514_DSP].platform_name = kstrdup_const(dev_name(dev), GFP_KERNEL);