El Wed, Feb 14, 2018 at 04:22:54PM -0800 Brian Norris ha dit:
> Hi Matthias,
>
> On Wed, Feb 14, 2018 at 03:51:56PM -0800, 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 <mka@xxxxxxxxxxxx>
> > ---
> > .../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;
>
> N00b question: are you sure this is legit? Is it possible to get
> START/STOP/START (or similar) with no prepare() in between?
To be honest I can't answer this question with authority and have to
defer it to the experts.
> > }
> >
> > @@ -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))
>
> You really want to be strict about error codes? What about -ENXIO ("no
> suitable firmware interface is present")? Seems like we should ignore
> that one too.
>
> In practice, it looks like many drivers that are reading optional
> properties like this just tend to ignore the return code entirely.
Ok, let's follow the common practice for optional properties
then. I'll update it in v2.
Thanks
Matthias
> > + return err;
> >
> > - snd_soc_codec_set_drvdata(codec, dmic_en);
> > + snd_soc_codec_set_drvdata(codec, dmic);
> >
> > return 0;
> > }
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