Re: [PATCH AUTOSEL for 4.14 029/110] ASoC: nau8825: fix issue that pop noise when start capture

From: Mark Brown
Date: Mon Feb 05 2018 - 06:42:18 EST


On Sat, Feb 03, 2018 at 06:00:42PM +0000, Sasha Levin wrote:
> From: Abhijeet Kumar <abhijeet.kumar@xxxxxxxxx>
>
> [ Upstream commit d070f7c703ef26e3db613f24206823f916272fc6 ]
>
> In skylake platform, we hear a loud pop noise(0 dB) at start of
> audio capture power up sequence. This patch removes the pop noise
> from the recording by adding a delay before enabling ADC.

> switch (event) {
> case SND_SOC_DAPM_POST_PMU:
> + msleep(125);
> regmap_update_bits(nau8825->regmap, NAU8825_REG_ENA_CTRL,

This is another one of these where I'm not convinced that backporting to
stable isn't going to introduce regressions - it will fix problems on
some systems but if someone really cares about a startup pop and has
arranged to do something like discard the start of the audio where the
pop occurs then this may cut off even more and cause them to miss
things.

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