Re: [PATCH 1/3] ARM: dts: imx6: phycore-som: fix arm and soc minimum voltage

From: Marco Felsch <m.felsch@pengutronix.de>
To: "Stefan Riedmüller" <s.riedmueller@phytec.de>
Cc: s.christ@phytec.de, chf.fritz@googlemail.com, robh+dt@kernel.org,
	linux-imx@nxp.com, kernel@pengutronix.de, c.hemp@phytec.de,
	shawnguo@kernel.org, festevam@gmail.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/3] ARM: dts: imx6: phycore-som: fix arm and soc minimum voltage
Date: Mon, 2 Dec 2019 13:42:00 +0100	[thread overview]
Message-ID: <20191202124200.mvwnsne2vnszyprj@pengutronix.de> (raw)
In-Reply-To: <ec29daf9-d87f-276f-2927-da66b153840f@phytec.de>

Hi Stefan,

On 19-12-02 11:09, Stefan Riedmüller wrote:
> Hi Marco,
> 
> your proposed setting is only valid for the LDO enabled case but not for the
> case where the LDO's are in bypass mode. Is that intended? In bypass mode it
> actually needs to be 0.925 V min for ARM and 1.15 V min for SOC.

The case is that the driver doesn't support the bypass mode currently so
yes it was intended.

> Did you experience an issue with the current settings or is this just a
> cosmetic change?

There is currently no issue because the internally LDO's don't try to
apply such a low voltage value. But I think it isn't a cosmetic change
because this value is wrong. We need to specify the valid voltage range.

Regards,
  Marco

> Regards,
> Stefan
> 
> 
> On 29.11.19 17:48, Marco Felsch wrote:
> > The current set minimum voltage of 730000mV seems to be wrong. I don't
> > know the document which specifies that but the imx6qdl datasheets says
> > that the minimum voltage should be 1.05V for VDD_ARM (LDO enabled, lowest
> > opp) and 1.275V for VDD_SOC (LDO enabled, lowest opp).
> > 
> > Fixes: ddec5d1c0047 ("ARM: dts: imx6: Add initial support for phyCORE-i.MX 6 SOM")
> > Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> > ---
> >   arch/arm/boot/dts/imx6qdl-phytec-phycore-som.dtsi | 4 ++--
> >   1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/arch/arm/boot/dts/imx6qdl-phytec-phycore-som.dtsi b/arch/arm/boot/dts/imx6qdl-phytec-phycore-som.dtsi
> > index 6486df3e2942..46d4953c5588 100644
> > --- a/arch/arm/boot/dts/imx6qdl-phytec-phycore-som.dtsi
> > +++ b/arch/arm/boot/dts/imx6qdl-phytec-phycore-som.dtsi
> > @@ -107,14 +107,14 @@
> >   		regulators {
> >   			vdd_arm: buck1 {
> >   				regulator-name = "vdd_arm";
> > -				regulator-min-microvolt = <730000>;
> > +				regulator-min-microvolt = <1050000>;
> >   				regulator-max-microvolt = <1380000>;
> >   				regulator-always-on;
> >   			};
> >   			vdd_soc: buck2 {
> >   				regulator-name = "vdd_soc";
> > -				regulator-min-microvolt = <730000>;
> > +				regulator-min-microvolt = <1275000>;
> >   				regulator-max-microvolt = <1380000>;
> >   				regulator-always-on;
> >   			};
> > 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel