linux-kernel - Re: [PATCH 15/17] ARM: dts: r8a7742: Add APMU nodes

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Message-ID: <CAMuHMdWdc5P3UyDZs1BPzAXZzkhvmZM8gVSDUnJBf=-dsH=izg@mail.gmail.com>
Date:   Mon, 18 May 2020 13:41:35 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Wolfram Sang <wsa+renesas@...g-engineering.com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        Prabhakar <prabhakar.csengg@...il.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 15/17] ARM: dts: r8a7742: Add APMU nodes

Hi Prabhakar,

reduced CC list
added CPUidle people

On Fri, May 15, 2020 at 5:10 PM Lad Prabhakar
<prabhakar.mahadev-lad.rj@...renesas.com> wrote:
> Add DT nodes for the Advanced Power Management Units (APMU), and use the
> enable-method to point out that the APMU should be used for SMP support.
>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> Reviewed-by: Marian-Cristian Rotariu <marian-cristian.rotariu.rb@...renesas.com>

Thanks for your patch!

> --- a/arch/arm/boot/dts/r8a7742.dtsi
> +++ b/arch/arm/boot/dts/r8a7742.dtsi
> @@ -18,6 +18,7 @@
>         cpus {
>                 #address-cells = <1>;
>                 #size-cells = <0>;
> +               enable-method = "renesas,apmu";

According to Documentation/devicetree/bindings/arm/cpus.yaml,
"enable-method" should be a property of the individual CPU nodes,
and not of the parent "cpus" container node.

However, so far we always put it in the parents "cpus" node, which works from
secondary CPU bringup, but may cause issues with CPUidle?

See also "[PATCH/RFC v2] ARM: dts: r8a7791: Move enable-method to CPU nodes"
https://lore.kernel.org/linux-arm-kernel/20190514085837.18325-1-geert+renesas@glider.be/
which so far has received no feedback from the DT or CPUidle people.

Thanks!

>                 cpu0: cpu@0 {
>                         device_type = "cpu";
> @@ -305,6 +306,18 @@
>                         #reset-cells = <1>;
>                 };
>
> +               apmu@...51000 {
> +                       compatible = "renesas,r8a7742-apmu", "renesas,apmu";
> +                       reg = <0 0xe6151000 0 0x188>;
> +                       cpus = <&cpu4 &cpu5 &cpu6 &cpu7>;
> +               };
> +
> +               apmu@...52000 {
> +                       compatible = "renesas,r8a7742-apmu", "renesas,apmu";
> +                       reg = <0 0xe6152000 0 0x188>;
> +                       cpus = <&cpu0 &cpu1 &cpu2 &cpu3>;
> +               };
> +
>                 rst: reset-controller@...60000 {
>                         compatible = "renesas,r8a7742-rst";
>                         reg = <0 0xe6160000 0 0x0100>;

Regardless:
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
and I'll see what I will queue in renesas-devel for v5.9 ;-)

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