linux-kernel - Re: [PATCH] ASoC: da7219: check SRM lock in trigger callback

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Message-ID: <20200210185905.GD14166@sirena.org.uk>
Date:   Mon, 10 Feb 2020 18:59:05 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Brent Lu <brent.lu@...el.com>
Cc:     alsa-devel@...a-project.org,
        Support Opensource <support.opensource@...semi.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, linux-kernel@...r.kernel.org,
        cychiang@...gle.com, mac.chiang@...el.com
Subject: Re: [PATCH] ASoC: da7219: check SRM lock in trigger callback

On Mon, Feb 10, 2020 at 04:16:51PM +0800, Brent Lu wrote:

> Intel sst firmware turns on BCLK/WCLK in START Ioctl call which timing is
> later than the DAPM SUPPLY event handler da7219_dai_event is called (in
> PREPARED state). Therefore, the SRM lock check always fail.
> 
> Moving the check to trigger callback could ensure the SRM is locked before
> DSP starts to process data and avoid possisble noise.

Independently of any other discussion trigger is expected to run very
fast so doesn't feel like a good place to do this - given that we're
talking about doing this to avoid noise the mute operation seems like a
more idiomatic place to do this, it exists to avoid playing back
glitches from the digitial interface during startup.

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