linux-kernel - Re: [PATCH] arm64: dts: hihope-rzg2-ex-lvds: Add power-supply and enable-gpios to backlight node

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Message-ID: <CA+V-a8vQyNUkVak-nFN+k9+nnf1icmATQgSW-2yt+Bbf9080Uw@mail.gmail.com>
Date:   Tue, 23 Nov 2021 20:18:56 +0000
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>,
        Magnus Damm <magnus.damm@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Biju Das <biju.das.jz@...renesas.com>
Subject: Re: [PATCH] arm64: dts: hihope-rzg2-ex-lvds: Add power-supply and
 enable-gpios to backlight node

Hi Geert,

Thank you for the review.

On Tue, Nov 23, 2021 at 2:44 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Mon, Nov 22, 2021 at 12:58 AM Lad Prabhakar
> <prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> > This patch adds missing power-supply and enable-gpios property to
> > backlight node. This fixes the warning "pwm-backlight backlight:
> > backlight supply power not found, using dummy regulator".
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Thanks for your patch!
>
> > --- a/arch/arm64/boot/dts/renesas/hihope-rzg2-ex-lvds.dtsi
> > +++ b/arch/arm64/boot/dts/renesas/hihope-rzg2-ex-lvds.dtsi
> > @@ -12,6 +12,17 @@
> >
> >                 brightness-levels = <0 2 8 16 32 64 128 255>;
> >                 default-brightness-level = <6>;
> > +               power-supply = <&reg_12v>;
> > +               enable-gpios = <&gpio6 7 GPIO_ACTIVE_HIGH>;
>
> According to the schematics (up to Rev. 4.00), GP6_07 is not connected?
>
Ouch sorry about that. When I noticed a warning with the regulator, I
saw the missing gpio property too and I pulled out the older schematic
with Rev2 which has GP6_07 :(
> > +       };
> > +
> > +       reg_12v: regulator2 {
>
> Using "regulatorN" as a node name is error-prone, and may lead to
> accidental clashes. Please use a more appropriate name.
>
> > +               compatible = "regulator-fixed";
> > +               regulator-name = "fixed-12V";
> > +               regulator-min-microvolt = <12000000>;
> > +               regulator-max-microvolt = <12000000>;
>
> Hmm, the AT1316A is a constant-current source, not a constant-voltage
> source? The -02 variant has a 0.2V Low Reference Voltage. Combined
> with the 1.1Ω resistor, that should give 181818 microamp.
>
Agreed.

Cheers,
Prabhakar

> > +               regulator-boot-on;
> > +               regulator-always-on;
> >         };
> >  };
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds