linux-kernel - Re: [PATCH 12/13] arm64: dts: renesas: r9a09g077: wire up DMA support for SPI

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Message-ID: <CAMuHMdWUPM=q7J_S_x7=CZoYxKm-v=7GGGkq9Nv0T14b8MBtpA@mail.gmail.com>
Date: Tue, 23 Dec 2025 15:24:37 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@...esas.com>
Cc: Fabrizio Castro <fabrizio.castro.jz@...esas.com>, Mark Brown <broonie@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Magnus Damm <magnus.damm@...il.com>, 
	Philipp Zabel <p.zabel@...gutronix.de>, linux-spi@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 12/13] arm64: dts: renesas: r9a09g077: wire up DMA support
 for SPI

Hi Cosmin,

On Mon, 1 Dec 2025 at 14:44, Cosmin Tanislav
<cosmin-gabriel.tanislav.xa@...esas.com> wrote:
> RZ/T2H (R9A09G077) has three DMA controllers that can be used by
> peripherals like SPI to offload data transfers from the CPU.
>
> Wire up the DMA channels for the SPI peripherals.
>
> Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@...esas.com>

Thanks for your patch!

> --- a/arch/arm64/boot/dts/renesas/r9a09g077.dtsi
> +++ b/arch/arm64/boot/dts/renesas/r9a09g077.dtsi
> @@ -200,6 +200,8 @@ rspi0: spi@...07000 {
>                         clocks = <&cpg CPG_CORE R9A09G077_CLK_PCLKM>,
>                                  <&cpg CPG_MOD 104>;
>                         clock-names = "pclk", "pclkspi";
> +                       dmas = <&dmac0 0x267a>, <&dmac0 0x267b>;
> +                       dma-names = "rx", "tx";

RZ/T2H does not seem to have restrictions about which DMA controllers
can be used by which SPI instance.  Hence shouldn't these point to
all three DMA controllers?

    dmas = <&dmac0 0x267a>, <&dmac0 0x267b>,
           <&dmac1 0x267a>, <&dmac1 0x267b>,
           <&dmac2 0x267a>, <&dmac2 0x267b>;
    dma-names = "rx", "tx", "rx", "tx", "rx", "tx";

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

The rest LGTM, 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