On 2018-02-15 01:51, Matthias Kaehlcke wrote:
> 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 <m...@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);
You don't need the 'if (dmic->gpio_en)'
> +
> + 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;
> }
What if instead of this trickery we try to handle the gpio/delay via
DAPM? SND_SOC_DAPM_AIF_OUT_E() might be just what we need?
We could remove the trigger, and will have no need for the prepare
callback either..
>
> @@ -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;
> }
>
- Péter
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