On some systems a delay is needed after switching on the clocks, to allow
the output to stabilize and avoid a popping noise at the beginning of
the recording. Add the optional device tree property 'wakeup-delay-ms'
and apply the specified delay after enabling the mic. A blocking delay
can't be applied in dmic_daiops_trigger() since the function is called
in atomic context. Instead use a DAPM event handler to set the enable
GPIO and apply the delay in the handler.
Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
---
Changes in v3:
- rebased on latest dmic topic branch
Changes in v2:
- use DAPM event handler instead of _prepare() and get rid of
_trigger()
- skip error check for optional 'wakeup-delay-ms' property
- updated commit message
.../devicetree/bindings/sound/dmic.txt | 2 +
sound/soc/codecs/dmic.c | 63 ++++++++++---------
2 files changed, 37 insertions(+), 28 deletions(-)
diff --git a/Documentation/devicetree/bindings/sound/dmic.txt b/Documentation/devicetree/bindings/sound/dmic.txt
index f7bf65611453..e957b4136716 100644
--- a/Documentation/devicetree/bindings/sound/dmic.txt
+++ b/Documentation/devicetree/bindings/sound/dmic.txt
@@ -8,6 +8,7 @@ Required properties:
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
Example node:
@@ -15,4 +16,5 @@ Example node:
compatible = "dmic-codec";
dmicen-gpios = <&gpio4 3 GPIO_ACTIVE_HIGH>;
num-channels = <1>;
+ wakeup-delay-ms <50>;
};
diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c
index 32a8f71d51f1..bac5bbb2dd59 100644
--- a/sound/soc/codecs/dmic.c
+++ b/sound/soc/codecs/dmic.c
@@ -19,6 +19,7 @@
*
*/
+#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
@@ -29,34 +30,33 @@
#include <sound/soc.h>
#include <sound/soc-dapm.h>
-static int dmic_daiops_trigger(struct snd_pcm_substream *substream,
- int cmd, struct snd_soc_dai *dai)
-{
- struct gpio_desc *dmic_en = snd_soc_dai_get_drvdata(dai);
+struct dmic {
+ struct gpio_desc *gpio_en;
+ int wakeup_delay;
+};
- if (!dmic_en)
- return 0;
+static int dmic_aif_event(struct snd_soc_dapm_widget *w,
+ struct snd_kcontrol *kcontrol, int event) {
+ struct snd_soc_codec *codec = snd_soc_dapm_to_codec(w->dapm);
+ struct dmic *dmic = snd_soc_codec_get_drvdata(codec);
- switch (cmd) {
- case SNDRV_PCM_TRIGGER_START:
- case SNDRV_PCM_TRIGGER_RESUME:
- case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
- gpiod_set_value(dmic_en, 1);
+ switch (event) {
+ case SND_SOC_DAPM_POST_PMU:
+ if (dmic->gpio_en)
+ gpiod_set_value(dmic->gpio_en, 1);
+
+ if (dmic->wakeup_delay)
+ msleep(dmic->wakeup_delay);
break;
- case SNDRV_PCM_TRIGGER_STOP:
- case SNDRV_PCM_TRIGGER_SUSPEND:
- case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
- gpiod_set_value(dmic_en, 0);
+ case SND_SOC_DAPM_POST_PMD:
+ if (dmic->gpio_en)
+ gpiod_set_value(dmic->gpio_en, 0);
break;
}
return 0;
}
-static const struct snd_soc_dai_ops dmic_dai_ops = {
- .trigger = dmic_daiops_trigger,
-};
-
static struct snd_soc_dai_driver dmic_dai = {
.name = "dmic-hifi",
.capture = {
@@ -68,26 +68,33 @@ 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)
{
- struct gpio_desc *dmic_en;
+ struct dmic *dmic;
+
+ dmic = devm_kzalloc(component->dev, sizeof(*dmic), GFP_KERNEL);
+ if (!dmic)
+ return -ENOMEM;
+
+ dmic->gpio_en = devm_gpiod_get_optional(component->dev,
+ "dmicen", GPIOD_OUT_LOW);
+ if (IS_ERR(dmic->gpio_en))
+ return PTR_ERR(dmic->gpio_en);
- dmic_en = devm_gpiod_get_optional(component->dev,
- "dmicen", GPIOD_OUT_LOW);
- if (IS_ERR(dmic_en))
- return PTR_ERR(dmic_en);
+ device_property_read_u32(component->dev, "wakeup-delay-ms",
+ &dmic->wakeup_delay);
- snd_soc_component_set_drvdata(component, dmic_en);
+ snd_soc_component_set_drvdata(component, dmic);
return 0;
}
static const struct snd_soc_dapm_widget dmic_dapm_widgets[] = {
- SND_SOC_DAPM_AIF_OUT("DMIC AIF", "Capture", 0,
- SND_SOC_NOPM, 0, 0),
+ SND_SOC_DAPM_AIF_OUT_E("DMIC AIF", "Capture", 0,
+ SND_SOC_NOPM, 0, 0, dmic_aif_event,
+ SND_SOC_DAPM_POST_PMU | SND_SOC_DAPM_POST_PMD),
SND_SOC_DAPM_INPUT("DMic"),
};
--
2.16.1.291.g4437f3f132-goog
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