linux-kernel - Re: [PATCH] ASoC: max98373: Added 10ms delay after amp software reset

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Date:   Wed, 22 Aug 2018 17:31:04 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     ryans.lee@...imintegrated.com
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        lkml <linux-kernel@...r.kernel.org>, ryan.lee.maxim@...il.com
Subject: Re: [PATCH] ASoC: max98373: Added 10ms delay after amp software reset

On Wed, Aug 22, 2018 at 5:21 PM Ryan Lee <ryans.lee@...imintegrated.com> wrote:
>
> Signed-off-by: Ryan Lee <ryans.lee@...imintegrated.com>
> ---
>  Changes : Applied 10ms delay after amp software reset.
>            10ms guard time is required for stability.
>  sound/soc/codecs/max98373.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/sound/soc/codecs/max98373.c b/sound/soc/codecs/max98373.c
> index 2764fae..6aaff03 100644
> --- a/sound/soc/codecs/max98373.c
> +++ b/sound/soc/codecs/max98373.c
> @@ -730,6 +730,7 @@ static int max98373_probe(struct snd_soc_component *component)
>         /* Software Reset */
>         regmap_write(max98373->regmap,
>                 MAX98373_R2000_SW_RESET, MAX98373_SOFT_RESET);
> +       mdelay(10);

Is it really necessary for the CPU to spin for 10msec here?
usleep_range() would be better solution.

>
>         /* IV default slot configuration */
>         regmap_write(max98373->regmap,
> @@ -818,6 +819,7 @@ static int max98373_resume(struct device *dev)
>
>         regmap_write(max98373->regmap,
>                 MAX98373_R2000_SW_RESET, MAX98373_SOFT_RESET);
> +       mdelay(10);
>         regcache_cache_only(max98373->regmap, false);
>         regcache_sync(max98373->regmap);
>         return 0;
> --
> 2.7.4
>

Thanks.

-- 
Dmitry