linux-kernel - Re: [PATCH v7 06/11] arm64: dts: mediatek: set vmc regulator as always on

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Date:   Mon, 15 May 2023 13:44:24 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     amergnat@...libre.com, Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Conor Dooley <conor+dt@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        Fabien Parent <fparent@...libre.com>,
        Kevin Hilman <khilman@...libre.com>
Subject: Re: [PATCH v7 06/11] arm64: dts: mediatek: set vmc regulator as
 always on

Il 11/05/23 18:29, amergnat@...libre.com ha scritto:
> From: Fabien Parent <fparent@...libre.com>
> 
> On downstream, we observe that the MSDC IP (used by the emmc, the micro
> SD card and the WiFi) isn't working properly if the VMC regulator is
> shutdown.
> 
> Make sure it is always on.

I don't understand the power tree of this board: if your VQMMC is VIO18 and
*not* VMC, why is that required?

The real question is if we're facing one more supply as requirement for newer
MediaTek SoCs and whether it would be a better idea to add that to the actual
driver (and/or as a power domain supply!!!) to both better represent the power
tree and to eventually allow deep power saving states.

Regards,
Angelo

> 
> Signed-off-by: Fabien Parent <fparent@...libre.com>
> Tested-by: Kevin Hilman <khilman@...libre.com>
> Signed-off-by: Alexandre Mergnat <amergnat@...libre.com>
> ---
>   arch/arm64/boot/dts/mediatek/mt8365-evk.dts | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/mediatek/mt8365-evk.dts b/arch/arm64/boot/dts/mediatek/mt8365-evk.dts
> index 752007d0598e..5d69b39c8746 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8365-evk.dts
> +++ b/arch/arm64/boot/dts/mediatek/mt8365-evk.dts
> @@ -137,6 +137,11 @@ &mt6357_pmic {
>   	#interrupt-cells = <2>;
>   };
>   
> +/* Needed by MSDC IP */
> +&mt6357_vmc_reg {
> +	regulator-always-on;
> +};
> +
>   &pio {
>   	gpio_keys: gpio-keys-pins {
>   		pins {
>