Hi,
On Thu, Feb 15, 2018 at 06:24:16PM -0800, 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 <mka@xxxxxxxxxxxx>
> ---
> 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
Looks good to me in general:
Brian Norris <briannorris@xxxxxxxxxxxx>
But I don't know much about the audio subsystem. One comment below.
>
> .../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 cf83c423394d..b5f60ac22ace 100644
> --- a/sound/soc/codecs/dmic.c
> +++ b/sound/soc/codecs/dmic.c
[...]
> 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),
Any good reason both are _POST_? It seems like you'd want them to be
inverses (e.g., power-power-up, and pre-power-down).
> SND_SOC_DAPM_INPUT("DMic"),
> };
>
Brian
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