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From:   Adam Ford <aford173@gmail.com>
Date:   Wed, 20 Mar 2019 08:41:27 -0500
Message-ID: <CAHCN7x+DKh8bR17C90o-zKKnFqWe_Yz5EM68xEiSY0W6ufNARA@mail.gmail.com>
Subject: Re: [PATCH 2/3] ARM: DTS: imx6q-logicpd: Reduce inrush current on start
To:     Shawn Guo <shawnguo@kernel.org>
Cc:     arm-soc <linux-arm-kernel@lists.infradead.org>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Mar 20, 2019 at 7:45 AM Shawn Guo <shawnguo@kernel.org> wrote:
>
> On Wed, Mar 06, 2019 at 08:04:00AM -0600, Adam Ford wrote:
> > The main 3.3V regulator sources a series of additional regulators.
> > This patch adds a small delay, so when the 3.3V regulator comes
> > on it delays a bit before the subsequent regulators can come on.
> > This reduces the inrush current a bit on the external DC power
> > supply.
> >
> > Fixes: 1c207f911fe9 ("ARM: dts: imx: Add support for Logic PD
> > i.MX6QD EVM")
>
> Same comment as patch #1.

The sourcing regulator occasionally cuts out because the inrush is so
high.  I would argue that preventing a hardware issue like that would
be a 'fix' and if it helps, I could add that to the description.

>
> >
> > Signed-off-by: Adam Ford <aford173@gmail.com>
>
> To match the convention, the 'DTS' in subject prefix should be
> lowercase.

I will fix in V2.

>
> Shawn

adam
>
> >
> > diff --git a/arch/arm/boot/dts/imx6-logicpd-baseboard.dtsi b/arch/arm/boot/dts/imx6-logicpd-baseboard.dtsi
> > index fb01fa6e4224..e31b6923cb72 100644
> > --- a/arch/arm/boot/dts/imx6-logicpd-baseboard.dtsi
> > +++ b/arch/arm/boot/dts/imx6-logicpd-baseboard.dtsi
> > @@ -99,6 +99,7 @@
> >               regulator-min-microvolt = <3300000>;
> >               regulator-max-microvolt = <3300000>;
> >               gpio = <&gpio1 26 GPIO_ACTIVE_HIGH>;
> > +             startup-delay-us = <70000>;
> >               enable-active-high;
> >               regulator-always-on;
> >       };
> > --
> > 2.17.1
> >