netdev - RE: [PATCH 3/3] dt-bindings: can: rcar

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Date:   Mon, 10 Sep 2018 09:54:27 +0000
From:   Fabrizio Castro <fabrizio.castro@...renesas.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
CC:     Wolfgang Grandegger <wg@...ndegger.com>,
        Marc Kleine-Budde <mkl@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        "David S. Miller" <davem@...emloft.net>,
        "linux-can@...r.kernel.org" <linux-can@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Simon Horman <horms@...ge.net.au>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Chris Paterson <Chris.Paterson2@...esas.com>,
        Biju Das <biju.das@...renesas.com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 3/3] dt-bindings: can: rcar_can: Add r8a774a1 support

Hello Geert,

Thank you for your feedback.

> Subject: Re: [PATCH 3/3] dt-bindings: can: rcar_can: Add r8a774a1 support
>
> Hi Fabrizio,
>
> On Thu, Aug 23, 2018 at 3:08 PM Fabrizio Castro
> <fabrizio.castro@...renesas.com> wrote:>
> > Document RZ/G2M (r8a774a1) SoC specific bindings and RZ/G2
> > generic bindings.
> >
> > Signed-off-by: Fabrizio Castro <fabrizio.castro@...renesas.com>
> > Signed-off-by: Chris Paterson <Chris.Paterson2@...esas.com>
> > Reviewed-by: Biju Das <biju.das@...renesas.com>
>
> Thanks for your patch!
>
> > --- a/Documentation/devicetree/bindings/net/can/rcar_can.txt
> > +++ b/Documentation/devicetree/bindings/net/can/rcar_can.txt
> > @@ -4,6 +4,7 @@ Renesas R-Car CAN controller Device Tree Bindings
> >  Required properties:
> >  - compatible: "renesas,can-r8a7743" if CAN controller is a part of R8A7743 SoC.
> >               "renesas,can-r8a7745" if CAN controller is a part of R8A7745 SoC.
> > +             "renesas,can-r8a774a1" if CAN controller is a part of R8A774A1 SoC.
>
> Looks good to me.
>
> >               "renesas,can-r8a7778" if CAN controller is a part of R8A7778 SoC.
> >               "renesas,can-r8a7779" if CAN controller is a part of R8A7779 SoC.
> >               "renesas,can-r8a7790" if CAN controller is a part of R8A7790 SoC.
> > @@ -17,6 +18,7 @@ Required properties:
> >               "renesas,rcar-gen2-can" for a generic R-Car Gen2 or RZ/G1
> >               compatible device.
> >               "renesas,rcar-gen3-can" for a generic R-Car Gen3 compatible device.
> > +             "renesas,rzg-gen2-can" for a generic RZ/G2 compatible device.
>
> AFAIK, the actual CAN module in RZ/G2M is fully compatible with the CAN
> module in R-Car Gen3 SoCs. The lack of clkp2 is merely an integration
> difference: as RZ/G2 SoCs do not have the CANFD module, and their CPG block
> doesn't provide the CANFD clock (so the CAN device node in DT cannot refer
> to that clock anyway).
>
> Hence I don't think there's a need to introduce a "renesas,rzg-gen2-can"
> compatible value.

Agreed, will drop RZ/G2 specific compatible string.

>
> >               When compatible with the generic version, nodes must list the
> >               SoC-specific version corresponding to the platform first
> >               followed by the generic version.
> > @@ -24,7 +26,9 @@ Required properties:
> >  - reg: physical base address and size of the R-Car CAN register map.
> >  - interrupts: interrupt specifier for the sole interrupt.
> >  - clocks: phandles and clock specifiers for 3 CAN clock inputs.
>
> You still have "3" here. Perhaps
> "Must contain a phandle and clock-specifier pair for each entry in
> clock-names."?

Good spot, we overlooked it.

>
> > -- clock-names: 3 clock input name strings: "clkp1", "clkp2", "can_clk".
> > +- clock-names: 2 clock input name strings for RZ/G2: "clkp1", "can_clk".
> > +              3 clock input name strings for every other SoC: "clkp1", "clkp2",
> > +              "can_clk".
>
> OK.
>
> > @@ -41,8 +45,9 @@ using the below properties:
> >  Optional properties:
> >  - renesas,can-clock-select: R-Car CAN Clock Source Select. Valid values are:
> >                             <0x0> (default) : Peripheral clock (clkp1)
> > -                           <0x1> : Peripheral clock (clkp2)
> > -                           <0x3> : Externally input clock
> > +                           <0x1> : Peripheral clock (clkp2) (not supported by
> > +                                   RZ/G2 devices)
> > +                           <0x3> : External input clock
>
> I already expressed my feelings about this property in my reply to the first
> patch ;-)

I know, I am not super happy about it either, maybe we will get a proper solution for this at some point in the future.

Thanks,
Fab

>
> 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



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