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    SubjectRe: [PATCH v3 07/10] riscv: boot: dts: r9a07g043: Add placeholder nodes
    Hi Conor,

    On Fri, Sep 16, 2022 at 12:40 AM Conor Dooley <mail@conchuod.ie> wrote:
    > On 15/09/2022 23:26, Lad, Prabhakar wrote:
    > > On Thu, Sep 15, 2022 at 10:36 PM <Conor.Dooley@microchip.com> wrote:
    > >> On 15/09/2022 19:15, Prabhakar wrote:
    > >>> riscv: boot: dts: r9a07g043: Add placeholder nodes
    > >>> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
    > >>> Add empty placeholder nodes to RZ/Five (R9A07G043) SoC DTSI.
    > >> Can you explain why do you need placeholder nodes for this and
    > >> cannot just directly include the other dtsis?
    > >>
    > > Since the RZ/G2UL SoC is ARM64 where it has a GIC and on RZ/Five SoC
    > > we have PLIC for interrupts. Also the interrupt numbering for RZ/Five
    > > SoC differs from RZ/G2UL SoC hence we are not directly using the
    > > RZ/G2UL SoC DTSI [0].
    > >
    > > [0] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/renesas/r9a07g043.dtsi?h=v6.0-rc5
    > >
    > > For the RZ/Five SMARC EVK I am re-using the below files [1] (SoM) and
    > > [2] (Carrier board) as the RZ/Five SMARC EVK is pin compatible. Since
    > > I am re-using these when trying to compile the RZ/Five DTB I get
    > > compilation errors since the nodes dont exist (and there is no way
    > > currently we can delete the node reference when the actual node itself
    > > isn't present) hence these place holders.
    > >
    > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/renesas/rzg2ul-smarc-som.dtsi?h=v6.0-rc5
    > > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/renesas/rzg2ul-smarc.dtsi?h=v6.0-rc5
    >
    > If this method is acceptable to Geert, this explanation 100% needs to
    > go into the commit message.

    We've been using these placeholders a lot in Renesas SoC-specific
    .dtsi files, as they allow us to introduce gradually support for a new SoC
    that is mounted on an existing PCB, and thus shares a board-specific
    .dtsi file. Hence I'm fine with this.

    However, I think more properties can be dropped from the placeholders.
    There is no need to have e.g. 'reg-names' and 'status = "disabled"'
    (there is no compatible value, so no matching is done).

    Gr{oetje,eeting}s,

    Geert

    --
    Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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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