linux-kernel - RE: [PATCH V5 07/12] arm64: dts: imx8mn-evk: update vdd

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Date:   Wed, 16 Nov 2022 02:31:49 +0000
From:   Peng Fan <peng.fan@....com>
To:     Marco Felsch <m.felsch@...gutronix.de>,
        "Peng Fan (OSS)" <peng.fan@....nxp.com>
CC:     "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH V5 07/12] arm64: dts: imx8mn-evk: update vdd_soc dvs
 voltage

> Subject: Re: [PATCH V5 07/12] arm64: dts: imx8mn-evk: update vdd_soc dvs
> voltage
> 
> Hi Peng,
> 
> On 22-11-15, Peng Fan (OSS) wrote:
> > From: Peng Fan <peng.fan@....com>
> >
> > Per schematic, BUCK1 is for VDD_SOC&DRAM&PU_0V9. The
> > nxp,dvs-run-voltage and nxp,dvs-standby-voltage need set for BUCK1, not
> BUCK2.
> > BUCK2 is for A53, which is handled by DVFS, so no need dvs property.
> >
> > Signed-off-by: Peng Fan <peng.fan@....com>
> > ---
> >  arch/arm64/boot/dts/freescale/imx8mn-evk.dts | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx8mn-evk.dts
> > b/arch/arm64/boot/dts/freescale/imx8mn-evk.dts
> > index 4eb467df5ba7..a5a7d74ec1d5 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8mn-evk.dts
> > +++ b/arch/arm64/boot/dts/freescale/imx8mn-evk.dts
> > @@ -47,6 +47,8 @@ buck1: BUCK1{
> >  				regulator-boot-on;
> >  				regulator-always-on;
> >  				regulator-ramp-delay = <3125>;
> > +				nxp,dvs-run-voltage = <950000>;
> 
> One last question on this. According the schematic the max should be
> 0.88/0.945V and you are going to set it to 0.950V.

No, my schematic shows the TYP voltage is 0.85/0.95V.
> 
> According the driver the nxp,dvs-run-voltage is just the same as the normal
> regulator voltage. So I would suggest to just use the nxp,dvs-standby-
> voltage property to enable the DVS feature since the run voltage is already
> handled by the regulator-min-microvolt/regulator-max-microvolt. So it
> would be just:
It should be fine to not set nxp,dvs-run-voltage, because bootloader already
set that.

Thanks,
Peng.
> 
> > +				nxp,dvs-standby-voltage = <750000>;
> 
> Regards,
>   Marco
> 
> >  			};
> >
> >  			buck2: BUCK2 {
> > @@ -56,8 +58,6 @@ buck2: BUCK2 {
> >  				regulator-boot-on;
> >  				regulator-always-on;
> >  				regulator-ramp-delay = <3125>;
> > -				nxp,dvs-run-voltage = <950000>;
> > -				nxp,dvs-standby-voltage = <850000>;
> >  			};
> >
> >  			buck4: BUCK4{
> > --
> > 2.37.1
> >
> >
> >