linux-kernel - Re: [PATCH v4 3/3] arm64: dts: reset: add microchip sparx5 switch reset driver

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Message-ID: <c92626b109dacc133a38036bfdea8876b8963603.camel@microchip.com>
Date:   Mon, 8 Feb 2021 08:58:40 +0100
From:   Steen Hegelund <steen.hegelund@...rochip.com>
To:     Rob Herring <robh@...nel.org>
CC:     Philipp Zabel <p.zabel@...gutronix.de>,
        Andrew Lunn <andrew@...n.ch>,
        Microchip Linux Driver Support <UNGLinuxDriver@...rochip.com>,
        "Alexandre Belloni" <alexandre.belloni@...tlin.com>,
        Gregory Clement <gregory.clement@...tlin.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v4 3/3] arm64: dts: reset: add microchip sparx5 switch
 reset driver

Hi Rob,

On Fri, 2021-02-05 at 16:35 -0600, Rob Herring wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
> 
> On Wed, Jan 20, 2021 at 09:19:21AM +0100, Steen Hegelund wrote:
> > This provides reset driver support for the Microchip Sparx5 PCB134
> > and
> > PCB135 reference boards.
> 
> This isn't a compatible change. You need an explanation why that's
> okay
> if that's intended.
> 
> > 
> > Signed-off-by: Steen Hegelund <steen.hegelund@...rochip.com>
> > ---
> >  arch/arm64/boot/dts/microchip/sparx5.dtsi | 14 +++++++++++---
> >  1 file changed, 11 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/arm64/boot/dts/microchip/sparx5.dtsi
> > b/arch/arm64/boot/dts/microchip/sparx5.dtsi
> > index 380281f312d8..4edbb9fcdce0 100644
> > --- a/arch/arm64/boot/dts/microchip/sparx5.dtsi
> > +++ b/arch/arm64/boot/dts/microchip/sparx5.dtsi
> > @@ -132,9 +132,17 @@ mux: mux-controller {
> >                       };
> >               };
> > 
> > -             reset@...010008 {
> > -                     compatible = "microchip,sparx5-chip-reset";
> > -                     reg = <0x6 0x11010008 0x4>;
> > +             gcb_ctrl: syscon@...010000 {
> > +                     compatible = "microchip,sparx5-gcb-syscon",
> > "syscon";
> > +                     reg = <0x6 0x11010000 0x10000>;
> > +             };
> > +
> > +             reset: reset-controller@0 {
> > +                     compatible = "microchip,sparx5-switch-reset";
> > +                     reg = <0x6 0x0 0x0>;
> 
> Your register length is 0?

Yes, I only use the syscons.

> 
> > +                     #reset-cells = <1>;
> > +                     cpu-syscon = <&cpu_ctrl>;
> 
> Can't you accomplish the same thing adding these to
> "microchip,sparx5-chip-reset"? Or possibly as a child node.
> 
> Define nodes based on h/w blocks, not as containers of things you
> happen
> to want for some driver.

Yes - I think the idea of using syscons came from another reset driver,
but it probably makes more sense to just use IO ranges directly.
I will try that out.

> 
> > +                     gcb-syscon = <&gcb_ctrl>;
> >               };
> > 
> >               uart0: serial@...100000 {
> > --
> > 2.29.2
> > 

Thanks for your comments

BR
Steen