[PATCH 1/4] arm64: dts: imx8mp: Describe VDD_ARM run and standby voltage for DH i.MX8M Plus DHCOM SoM

[Marco Felsch]

On 23-09-07, Marek Vasut wrote:
> On 9/7/23 17:45, Marco Felsch wrote:
> > Hi Marek,
> 
> Hi,
> 
> > On 23-08-31, Marek Vasut wrote:
> > > Describe VDD_ARM (BUCK2) run and standby voltage in DT.
> > > 
> > > Signed-off-by: Marek Vasut <marex at denx.de>
> > > ---
> > > Cc: Conor Dooley <conor+dt at kernel.org>
> > > Cc: Fabio Estevam <festevam at gmail.com>
> > > Cc: Frieder Schrempf <frieder.schrempf at kontron.de>
> > > Cc: Geert Uytterhoeven <geert+renesas at glider.be>
> > > Cc: Krzysztof Kozlowski <krzysztof.kozlowski+dt at linaro.org>
> > > Cc: Magnus Damm <magnus.damm at gmail.com>
> > > Cc: Marek Vasut <marex at denx.de>
> > > Cc: NXP Linux Team <linux-imx at nxp.com>
> > > Cc: Peng Fan <peng.fan at nxp.com>
> > > Cc: Pengutronix Kernel Team <kernel at pengutronix.de>
> > > Cc: Rob Herring <robh+dt at kernel.org>
> > > Cc: Sascha Hauer <s.hauer at pengutronix.de>
> > > Cc: Shawn Guo <shawnguo at kernel.org>
> > > Cc: devicetree at vger.kernel.org
> > > Cc: linux-arm-kernel at lists.infradead.org
> > > ---
> > >   arch/arm64/boot/dts/freescale/imx8mp-dhcom-som.dtsi | 2 ++
> > >   1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/arch/arm64/boot/dts/freescale/imx8mp-dhcom-som.dtsi b/arch/arm64/boot/dts/freescale/imx8mp-dhcom-som.dtsi
> > > index cb1953d14aa90..1644b56c3953d 100644
> > > --- a/arch/arm64/boot/dts/freescale/imx8mp-dhcom-som.dtsi
> > > +++ b/arch/arm64/boot/dts/freescale/imx8mp-dhcom-som.dtsi
> > > @@ -293,6 +293,8 @@ buck1: BUCK1 {	/* VDD_SOC (dual-phase with BUCK3) */
> > >   			};
> > >   			buck2: BUCK2 {	/* VDD_ARM */
> > > +				nxp,dvs-run-voltage = <950000>;
> > 
> > Why do we need to set the "nxp,dvs-run-voltage"? If I read the driver
> > correctly, then nxp,dvs-run-voltage and regulator-min/max-microvolt are
> > touching the same register.
> 
> My understanding is that the nxp,dvs-run-voltage selects the default
> regulator voltage which is configured early on once the regulator is
> detected in DT (see of_parse_cb callback in the PCA9450 regulator driver)
> and may be higher than regulator-min-microvolt, while later on DVFS can
> adjust the regulator in range of regulator-min-microvolt to
> regulator-max-microvolt .

Right, albeit I think that the bootloader already did the
initialization once. Anyway the change lgtm:

Reviewed-by: Marco Felsch <m.felsch at pengutronix.de>

> > > +				nxp,dvs-standby-voltage = <850000>;
> > >   				regulator-min-microvolt = <850000>;
> > >   				regulator-max-microvolt = <1000000>;
> 
> [...]
>