linux-kernel - Re: [PATCH v9 2/6] dt: bindings: add mt7621-clk device tree binding documentation

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Message-ID: <CAMhs-H_RoA-JvT9Q1K+8tEA1vqS6HWuE-D4=kWVsoOWTwjTGbw@mail.gmail.com>
Date:   Sat, 6 Mar 2021 08:12:43 +0100
From:   Sergio Paracuellos <sergio.paracuellos@...il.com>
To:     Rob Herring <robh@...nel.org>
Cc:     Stephen Boyd <sboyd@...nel.org>, John Crispin <john@...ozen.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Greg KH <gregkh@...uxfoundation.org>,
        "open list:COMMON CLK FRAMEWORK" <linux-clk@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        "open list:MIPS" <linux-mips@...r.kernel.org>,
        "open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
        NeilBrown <neil@...wn.name>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 2/6] dt: bindings: add mt7621-clk device tree binding documentation

Hi Rob,

On Fri, Mar 5, 2021 at 11:47 PM Rob Herring <robh@...nel.org> wrote:
[snip]
> > +
> > +  ralink,sysctl:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description:
> > +      phandle of syscon used to control system registers
> > +
> > +  ralink,memctl:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description:
> > +      phandle of syscon used to control memory registers
>
> I assume one of these phandles are the main registers for the clocks?
> Make this a child node and drop that phandle.

The 'ralink,sysctl' phandle is to read bootstrap register to be able
to derive xtal and a clk gate register for the peripherals.
The 'ralink,memctl' phandle is to read the cpu clock frequency from
the memory controller.

So there is not "main registers". I already put this as a child node
in v4 and I was told to get rid of child nodes. I need this as a
regmap to other DT node registers (sysctl, and memctl) to be able to
use the driver without specific architecture operations and properly
enable for COMPILE_TEST without dirty Makefile arch flags. Both sysctl
and memctl has no other child nodes, and I think that's why I was told
to avoid child nodes at the end. I explained here [0] current sysctl
and memctl in the mt7621 device tree and my view of the need for this
two syscons:

[0]: https://lkml.org/lkml/2021/1/2/9

So to avoid to send again "a previous version" on this patch, please
guide me in the correct thing to do. Stephen, Rob, I will be really
happy with your help :)

Best regards,
    Sergio Paracuellos
>
> > +
> > +  clock-output-names:
> > +    maxItems: 8
> > +
> > +required:
> > +  - compatible
> > +  - '#clock-cells'
> > +  - ralink,sysctl
> > +  - ralink,memctl
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/mt7621-clk.h>
> > +
> > +    pll {
> > +      compatible = "mediatek,mt7621-clk";
> > +      #clock-cells = <1>;
> > +      ralink,sysctl = <&sysc>;
> > +      ralink,memctl = <&memc>;
> > +      clock-output-names = "xtal", "cpu", "bus",
> > +                           "50m", "125m", "150m",
> > +                           "250m", "270m";
> > +    };
> > --
> > 2.25.1
> >