linux-kernel - Re: [PATCH v4 4/6] arm64: dts: renesas: rzg3s-smarc-som: Update dma-ranges for PCIe

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Message-ID: <CAMuHMdWeHoUe-=7TDetnDQbLQsKGf4pDGpSdz3xEVLs_Rst9qQ@mail.gmail.com>
Date: Thu, 18 Sep 2025 12:00:04 +0200
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Claudiu Beznea <claudiu.beznea@...on.dev>
Cc: bhelgaas@...gle.com, lpieralisi@...nel.org, kwilczynski@...nel.org, 
	mani@...nel.org, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	magnus.damm@...il.com, p.zabel@...gutronix.de, linux-pci@...r.kernel.org, 
	linux-renesas-soc@...r.kernel.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>, 
	Wolfram Sang <wsa+renesas@...g-engineering.com>
Subject: Re: [PATCH v4 4/6] arm64: dts: renesas: rzg3s-smarc-som: Update
 dma-ranges for PCIe

Hi Claudiu,

On Thu, 18 Sept 2025 at 11:47, Claudiu Beznea <claudiu.beznea@...on.dev> wrote:
> On 9/18/25 12:09, Geert Uytterhoeven wrote:
> > On Fri, 12 Sept 2025 at 14:24, Claudiu <claudiu.beznea@...on.dev> wrote:
> >> From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >>
> >> The first 128MB of memory is reserved on this board for secure area.
> >> Secure area is a RAM region used by firmware. The rzg3s-smarc-som.dtsi
> >> memory node (memory@...00000) excludes the secure area.
> >> Update the PCIe dma-ranges property to reflect this.
> >>
> >> Tested-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> >> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> >
> > Thanks for your patch!
> >
> >> --- a/arch/arm64/boot/dts/renesas/rzg3s-smarc-som.dtsi
> >> +++ b/arch/arm64/boot/dts/renesas/rzg3s-smarc-som.dtsi
> >> @@ -214,6 +214,16 @@ &sdhi2 {
> >>  };
> >>  #endif
> >>
> >> +&pcie {
> >> +       /* First 128MB is reserved for secure area. */
> >
> > Do you really have to take that into account here?  I believe that
> > 128 MiB region will never be used anyway, as it is excluded from the
> > memory map (see memory@...00000).
> >
> >> +       dma-ranges = <0x42000000 0 0x48000000 0 0x48000000 0x0 0x38000000>;
> >
> > Hence shouldn't you add
> >
> >     dma-ranges = <0x42000000 0 0x48000000 0 0x48000000 0x0 0x38000000>;

Oops, I really meant (forgot to edit after copying it):

    dma-ranges = <0x42000000 0 0x40000000 0 0x40000000 0x0 0x40000000>;

> >
> > to the pcie node in arch/arm64/boot/dts/renesas/r9a08g045s33.dtsi
> > instead, like is done for all other Renesas SoCs that have PCIe?
>
> I chose to add it here as the rzg3s-smarc-som.dtsi is the one that defines
> the available memory for board, as the available memory is something board
> dependent.

But IMHO it is independent from the amount of memory on the board.
On other SoCs, it has a comment:

     /* Map all possible DDR as inbound ranges */

>
> If you consider it is better to have it in the SoC file, please let me know.

Hence yes please.

However, I missed you already have:

    /* Map all possible DRAM ranges (4 GB). */
    dma-ranges = <0x42000000 0 0x40000000 0 0x40000000 0x1 0x0>;

in r9a08g045.dtsi, so life's good.

+
> >> +};
> >> +
> >> +&pcie_port0 {
> >> +       clocks = <&versa3 5>;
> >> +       clock-names = "ref";
> >> +};
> >
> > This is not related.
>
> Ah, right! Could you please let me know if you prefer to have another patch
> or to update the patch description?

Given the dma-ranges changes is IMHO not needed, this can just be
a separate patch.

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