Re: [PATCH V2 09/15] arm64: dts: imx8mn-evk: set off-on-delay-us in regulator

[Peng Fan]

On 10/28/2022 11:02 PM, Marco Felsch wrote:
> On 22-10-24, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@xxxxxxx>
> >
> > Some SD Card controller and power circuitry has increased capacitance,
> > so the usual toggling of regulator to power the card off and on
> > is insufficient.
> >
> > According to SD spec, for sd card power reset operation, the sd card
> > supply voltage needs to be lower than 0.5v and keep over 1ms, otherwise,
> > next time power back the sd card supply voltage to 3.3v, sd card can't
> > support SD3.0 mode again.
> >
> > This patch add the off-on-delay-us, make sure the sd power reset behavior
> > is align with the specification. Without this patch, when do quick system
> > suspend/resume test, some sd card can't work at SD3.0 mode after system
> > resume back.
> >
> > Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> > ---
> >   arch/arm64/boot/dts/freescale/imx8mn-evk.dtsi | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mn-evk.dtsi b/arch/arm64/boot/dts/freescale/imx8mn-evk.dtsi
> > index 261c36540079..2b4395854283 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mn-evk.dtsi
> > +++ b/arch/arm64/boot/dts/freescale/imx8mn-evk.dtsi
> > @@ -36,6 +36,7 @@ reg_usdhc2_vmmc: regulator-usdhc2 {
> >   		regulator-min-microvolt = <3300000>;
> >   		regulator-max-microvolt = <3300000>;
> >   		gpio = <&gpio2 19 GPIO_ACTIVE_HIGH>;
> > +		off-on-delay-us = <12000>;
>
> All others are using 20000us, did you changed the HW?

This is i.MX8MN. This value should be safe I think,
since it goes through several NXP releases.

Thanks,
Peng.

> Regards,
>    Marco
>
> >   		enable-active-high;
> >   	};
> >   
> > --
> > 2.37.1