On some systems a delay is needed after switching on the clocks, to allow the DMIC 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 in the new dmic_daiops_prepare().
Signed-off-by: Matthias Kaehlcke mka@chromium.org --- .../devicetree/bindings/sound/dmic.txt | 2 + sound/soc/codecs/dmic.c | 54 ++++++++++++++----- 2 files changed, 42 insertions(+), 14 deletions(-)
diff --git a/Documentation/devicetree/bindings/sound/dmic.txt b/Documentation/devicetree/bindings/sound/dmic.txt index 54c8ef6498a8..de741c6609d0 100644 --- a/Documentation/devicetree/bindings/sound/dmic.txt +++ b/Documentation/devicetree/bindings/sound/dmic.txt @@ -7,10 +7,12 @@ Required properties:
Optional properties: - dmicen-gpios: GPIO specifier for dmic to control start and stop + - wakeup-delay-ms: Delay (in ms) after enabling the DMIC
Example node:
dmic_codec: dmic@0 { compatible = "dmic-codec"; dmicen-gpios = <&gpio4 3 GPIO_ACTIVE_HIGH>; + wakeup-delay-ms <50>; }; diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c index b88a1ee66f80..11f6abf11074 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> @@ -29,24 +30,38 @@ #include <sound/soc.h> #include <sound/soc-dapm.h>
+struct dmic { + struct gpio_desc *gpio_en; + int wakeup_delay; +}; + +static int dmic_daiops_prepare(struct snd_pcm_substream *substream, + struct snd_soc_dai *dai) +{ + struct dmic *dmic = snd_soc_dai_get_drvdata(dai); + + if (dmic->gpio_en) + gpiod_set_value(dmic->gpio_en, 1); + + if (dmic->wakeup_delay) + msleep(dmic->wakeup_delay); + + return 0; +} + 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 *dmic = snd_soc_dai_get_drvdata(dai);
- if (!dmic_en) + if (!dmic->gpio_en) return 0;
switch (cmd) { - case SNDRV_PCM_TRIGGER_START: - case SNDRV_PCM_TRIGGER_RESUME: - case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: - gpiod_set_value(dmic_en, 1); - break; case SNDRV_PCM_TRIGGER_STOP: case SNDRV_PCM_TRIGGER_SUSPEND: case SNDRV_PCM_TRIGGER_PAUSE_PUSH: - gpiod_set_value(dmic_en, 0); + gpiod_set_value(dmic->gpio_en, 0); break; }
@@ -54,6 +69,7 @@ static int dmic_daiops_trigger(struct snd_pcm_substream *substream, }
static const struct snd_soc_dai_ops dmic_dai_ops = { + .prepare = dmic_daiops_prepare, .trigger = dmic_daiops_trigger, };
@@ -73,14 +89,24 @@ static struct snd_soc_dai_driver dmic_dai = {
static int dmic_codec_probe(struct snd_soc_codec *codec) { - struct gpio_desc *dmic_en; + struct dmic *dmic; + int err; + + dmic = devm_kzalloc(codec->dev, sizeof(*dmic), GFP_KERNEL); + if (!dmic) + return -ENOMEM; + + dmic->gpio_en = devm_gpiod_get_optional(codec->dev, + "dmicen", GPIOD_OUT_LOW); + if (IS_ERR(dmic->gpio_en)) + return PTR_ERR(dmic->gpio_en);
- dmic_en = devm_gpiod_get_optional(codec->dev, - "dmicen", GPIOD_OUT_LOW); - if (IS_ERR(dmic_en)) - return PTR_ERR(dmic_en); + err = device_property_read_u32(codec->dev, "wakeup-delay-ms", + &dmic->wakeup_delay); + if (err && (err != -EINVAL)) + return err;
- snd_soc_codec_set_drvdata(codec, dmic_en); + snd_soc_codec_set_drvdata(codec, dmic);
return 0; }