linux-kernel - Re: [PATCH] regulator: wm8994: Use PROBE_FORCE

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Date:   Thu, 23 Mar 2023 11:40:35 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
CC:     <linux-kernel@...r.kernel.org>,
        <linux-samsung-soc@...r.kernel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Douglas Anderson <dianders@...omium.org>,
        <patches@...nsource.cirrus.com>
Subject: Re: [PATCH] regulator: wm8994: Use PROBE_FORCE_SYNCHRONOUS

On Thu, Mar 23, 2023 at 09:33:12AM +0100, Marek Szyprowski wrote:
> Restore synchronous probing for wm8994 regulators because otherwise the
> sound device is never initialized on Exynos5250-based Arndale board.
> 
> Fixes: 259b93b21a9f ("regulator: Set PROBE_PREFER_ASYNCHRONOUS for drivers that existed in 4.14")
> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>  drivers/regulator/wm8994-regulator.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/regulator/wm8994-regulator.c b/drivers/regulator/wm8994-regulator.c
> index 8921051a00e9..2946db448aec 100644
> --- a/drivers/regulator/wm8994-regulator.c
> +++ b/drivers/regulator/wm8994-regulator.c
> @@ -227,7 +227,7 @@ static struct platform_driver wm8994_ldo_driver = {
>  	.probe = wm8994_ldo_probe,
>  	.driver		= {
>  		.name	= "wm8994-ldo",
> -		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +		.probe_type = PROBE_FORCE_SYNCHRONOUS,
>  	},
>  };

Acked-by: Charles Keepax <ckeepax@...nsource.cirrus.com>

Yes, these seems to be a wider problem with these complex CODECs
that have an internal LDO. Changing to async probe, means the
internal LDO driver doesn't probe before the code in the main MFD
carries on, which means the regulator framework finds no driver
and swaps in the dummy. Which means the CODEC never powers up.

I think these basically have to be forced sync, I will do a patch
to update the other devices working like this.

Thanks,
Charles