linux-kernel - Re: [PATCH 1/4] ARM: dts: r8a7742-iwg21d-q7: Enable PCIe Controller

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Message-ID: <CAMuHMdVVvDEq-GSsPDrx09TCfGCWkNQvGYrNWP4gK2=63G2z1w@mail.gmail.com>
Date:   Thu, 3 Sep 2020 12:18:45 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Magnus Damm <magnus.damm@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Prabhakar <prabhakar.csengg@...il.com>
Subject: Re: [PATCH 1/4] ARM: dts: r8a7742-iwg21d-q7: Enable PCIe Controller

Hi Prabhakar,

On Tue, Aug 25, 2020 at 6:28 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> Enable PCIe Controller and set PCIe bus clock frequency.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> Reviewed-by: Chris Paterson <Chris.Paterson2@...esas.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
i.e. will queue in renesas-devel for v5.10.

One thing to double-check below.

> --- a/arch/arm/boot/dts/r8a7742-iwg21d-q7.dts
> +++ b/arch/arm/boot/dts/r8a7742-iwg21d-q7.dts
> @@ -238,6 +238,18 @@
>         /* status = "okay"; */
>  };
>
> +&pcie_bus_clk {
> +       clock-frequency = <100000000>;
> +};
> +
> +&pciec {
> +       /* SW2[6] determines which connector is activated
> +        * ON = PCIe X4 (connector-J7)
> +        * OFF = mini-PCIe (connector-J26)

The table on page 14 says it's the other way around.

According to the CBTL02042ABQ datasheet, PCIe_SEL = low
selects the first channel (PCIe x4), while PCIe_SEL = high selects the
second channel (mini-PCIe).
Enabling the switch ties the signal low, so the table must be wrong.

> +        */
> +       status = "okay";
> +};
> +
>  &pfc {
>         avb_pins: avb {
>                 groups = "avb_mdio", "avb_gmii";

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