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@chromium.org
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@chromium.org
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