[alsa-devel] Applied "ASoC: dmic: introduce mode switch delay" to the asoc tree

[Mark Brown]

The patch

   ASoC: dmic: introduce mode switch delay

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From bc0a7dbc5a54a06b925064adba8b07d65acf8718 Mon Sep 17 00:00:00 2001
From: Jenny TC <jenny.tc at intel.com>
Date: Wed, 28 Nov 2018 12:22:45 +0530
Subject: [PATCH] ASoC: dmic: introduce mode switch delay

On startup, applications such as PulseAudio or CRAS enable playback or
capture on all PCM devices to verify that configurations are correct,
and close them immediately. For DMICs, this can result in the clock
being turned off very quickly, which may not compatible with internal
state machine transition requirements.

This patch add a mode-switch delay which will prevent the clock from
being turned off without complying with manufacturer timing
specifications. While the DMIC clock may be controlled at a lower level,
be it with hardware or firmware, applying the delay during the
STOP_TRIGGER phase ensures that there is no race condition, e.g. with
the hardware/firmware turning off the clock earlier

Signed-off-by: Sathyanarayana Nujella <sathyanarayana.nujella at intel.com>
Signed-off-by: Jairaj Arava <jairaj.arava at intel.com>
Signed-off-by: Harsha Priya <harshapriya.n at intel.com>
Signed-off-by: Jenny TC <jenny.tc at intel.com>
Signed-off-by: Mark Brown <broonie at kernel.org>
---
 .../devicetree/bindings/sound/dmic.txt        |  2 ++
 sound/soc/codecs/dmic.c                       | 35 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/Documentation/devicetree/bindings/sound/dmic.txt b/Documentation/devicetree/bindings/sound/dmic.txt
index e957b4136716..32e871037269 100644
--- a/Documentation/devicetree/bindings/sound/dmic.txt
+++ b/Documentation/devicetree/bindings/sound/dmic.txt
@@ -9,6 +9,7 @@ Optional properties:
 	- dmicen-gpios: GPIO specifier for dmic to control start and stop
 	- num-channels: Number of microphones on this DAI
 	- wakeup-delay-ms: Delay (in ms) after enabling the DMIC
+	- modeswitch-delay-ms: Delay (in ms) to complete DMIC mode switch
 
 Example node:
 
@@ -17,4 +18,5 @@ Example node:
 		dmicen-gpios = <&gpio4 3 GPIO_ACTIVE_HIGH>;
 		num-channels = <1>;
 		wakeup-delay-ms <50>;
+		modeswitch-delay-ms <35>;
 	};
diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c
index 71322e0410ee..f4eb0a438a3a 100644
--- a/sound/soc/codecs/dmic.c
+++ b/sound/soc/codecs/dmic.c
@@ -30,9 +30,36 @@
 #include <sound/soc.h>
 #include <sound/soc-dapm.h>
 
+#define MAX_MODESWITCH_DELAY 70
+static int modeswitch_delay;
+module_param(modeswitch_delay, uint, 0644);
+
 struct dmic {
 	struct gpio_desc *gpio_en;
 	int wakeup_delay;
+	/* Delay after DMIC mode switch */
+	int modeswitch_delay;
+};
+
+int dmic_daiops_trigger(struct snd_pcm_substream *substream,
+		int cmd, struct snd_soc_dai *dai)
+{
+	struct snd_soc_component *component = dai->component;
+	struct dmic *dmic = snd_soc_component_get_drvdata(component);
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_STOP:
+		if (dmic->modeswitch_delay)
+			mdelay(dmic->modeswitch_delay);
+
+		break;
+	}
+
+	return 0;
+}
+
+static const struct snd_soc_dai_ops dmic_dai_ops = {
+	.trigger	= dmic_daiops_trigger,
 };
 
 static int dmic_aif_event(struct snd_soc_dapm_widget *w,
@@ -68,6 +95,7 @@ static struct snd_soc_dai_driver dmic_dai = {
 			| SNDRV_PCM_FMTBIT_S24_LE
 			| SNDRV_PCM_FMTBIT_S16_LE,
 	},
+	.ops    = &dmic_dai_ops,
 };
 
 static int dmic_component_probe(struct snd_soc_component *component)
@@ -85,6 +113,13 @@ static int dmic_component_probe(struct snd_soc_component *component)
 
 	device_property_read_u32(component->dev, "wakeup-delay-ms",
 				 &dmic->wakeup_delay);
+	device_property_read_u32(component->dev, "modeswitch-delay-ms",
+				 &dmic->modeswitch_delay);
+	if (modeswitch_delay)
+		dmic->modeswitch_delay  = modeswitch_delay;
+
+	if (dmic->modeswitch_delay > MAX_MODESWITCH_DELAY)
+		dmic->modeswitch_delay = MAX_MODESWITCH_DELAY;
 
 	snd_soc_component_set_drvdata(component, dmic);
 
-- 
2.19.0.rc2