linux-kernel - Re: [PATCH 1/2] arm64: dts: renesas: r9a09g056: Add DMA support for RSPI channels

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Message-ID: <CAMuHMdVeB0xYbnHx-RYf3F4aw4TQOzC39A_MWc8PoROo8-p1mA@mail.gmail.com>
Date: Thu, 8 Jan 2026 14:17:50 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: Magnus Damm <magnus.damm@...il.com>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH 1/2] arm64: dts: renesas: r9a09g056: Add DMA support for
 RSPI channels

Hi Prabhakar,

On Mon, 15 Dec 2025 at 17:34, Prabhakar <prabhakar.csengg@...il.com> wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
>
> Enable DMA support for RSPI channels.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>

Thanks for your patch!

> --- a/arch/arm64/boot/dts/renesas/r9a09g056.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r9a09g056.dtsi
> @@ -679,6 +679,8 @@ rspi0: spi@...00000 {
>                         clock-names = "pclk", "pclk_sfr", "tclk";
>                         resets = <&cpg 0x7b>, <&cpg 0x7c>;
>                         reset-names = "presetn", "tresetn";
> +                       dmas = <&dmac0 0x448c>, <&dmac0 0x448d>;
> +                       dma-names = "rx", "tx";

RZ/V2N does not seem to have restrictions about which DMA controllers
can be used by which SPI instance.  Hence shouldn't these point to
all five DMA controllers?

    dmas = <&dmac0 0x448c>, <&dmac0 0x448d>,
           <&dmac1 0x448c>, <&dmac1 0x448d>,
           <&dmac2 0x448c>, <&dmac2 0x448d>,
           <&dmac3 0x448c>, <&dmac3 0x448d>,
           <&dmac4 0x448c>, <&dmac4 0x448d>;
    dma-names = "rx", "tx", "rx", "tx", "rx", "tx",
                "rx", "tx", "rx", "tx";

Note that this requires updating the DT bindings, as they currently
restrict dma to two entries.

>                         power-domains = <&cpg>;
>                         #address-cells = <1>;
>                         #size-cells = <0>;

The actual DMA specifier values are OK, so
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>

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