On 2018-02-16 19:53, Matthias Kaehlcke wrote:
> 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 <m...@chromium.org>
Reviewed-by: Peter Ujfalusi <peter.ujfal...@ti.com>
> ---
> 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"),
> };
>
>
- Péter
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