linux-kernel - Re: [PATCH v4 2/6] dt: bindings: add mt7621-clk device tree binding documentation

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Date:   Thu, 17 Dec 2020 11:01:39 +0100
From:   Sergio Paracuellos <sergio.paracuellos@...il.com>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        John Crispin <john@...ozen.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Greg KH <gregkh@...uxfoundation.org>,
        Chuanhong Guo <gch981213@...il.com>,
        Weijie Gao <hackpascal@...il.com>,
        "open list:COMMON CLK FRAMEWORK" <linux-clk@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "open list:MIPS" <linux-mips@...r.kernel.org>,
        "open list:STAGING SUBSYSTEM" <devel@...verdev.osuosl.org>,
        NeilBrown <neil@...wn.name>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH v4 2/6] dt: bindings: add mt7621-clk device tree binding documentation

Hi Stephen,

Thanks for the review!

On Thu, Dec 17, 2020 at 9:58 AM Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting Sergio Paracuellos (2020-11-22 01:55:52)
> > Adds device tree binding documentation for clocks in the
> > MT7621 SOC.
> >
> > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>
> > ---
> >  .../bindings/clock/mediatek,mt7621-clk.yaml   | 67 +++++++++++++++++++
> >  1 file changed, 67 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/clock/mediatek,mt7621-clk.yaml
> >
>
> Rob?
>
> > diff --git a/Documentation/devicetree/bindings/clock/mediatek,mt7621-clk.yaml b/Documentation/devicetree/bindings/clock/mediatek,mt7621-clk.yaml
> > new file mode 100644
> > index 000000000000..6aca4c1a4a46
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/mediatek,mt7621-clk.yaml
> > @@ -0,0 +1,67 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/clock/mediatek,mt7621-clk.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: MT7621 Clock Device Tree Bindings
> > +
> > +maintainers:
> > +  - Sergio Paracuellos <sergio.paracuellos@...il.com>
> > +
> > +description: |
> > +  The MT7621 has a PLL controller from where the cpu clock is provided
> > +  as well as derived clocks for the bus and the peripherals. It also
> > +  can gate SoC device clocks.
> > +
> > +  Each clock is assigned an identifier and client nodes use this identifier
> > +  to specify the clock which they consume.
> > +
> > +  All these identifiers could be found in:
> > +  [1]: <include/dt-bindings/clock/mt7621-clk.h>.
> > +
> > +  The mt7621 clock node should be the child of a syscon node with the
> > +  required property:
> > +
> > +  - compatible: Should be one of the following:
> > +                "mediatek,mt7621-sysc", "syscon"
> > +
> > +  Refer to the bindings described in
> > +  Documentation/devicetree/bindings/mfd/syscon.yaml
> > +
> > +properties:
> > +  compatible:
> > +    const: mediatek,mt7621-clk
> > +
> > +  "#clock-cells":
> > +    description:
> > +      The first cell indicates the clock gate number, see [1] for available
> > +      clocks.
> > +    const: 1
> > +
> > +  clock-output-names:
> > +    maxItems: 8
> > +
> > +required:
> > +  - compatible
> > +  - '#clock-cells'
> > +  - clock-output-names
>
> Why is clock-output-names required? Hopefully it is not required.

Not really, can be removed from here.

>
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/clock/mt7621-clk.h>
> > +
> > +    sysc: sysc@0 {
>
> syscon@0? I don't think sysc is a standard node name.

Ok, I will change this into syscon@0 in both bindings and device tree file.

>
> > +      compatible = "mediatek,mt7621-sysc", "syscon";
> > +      reg = <0x0 0x100>;
> > +
> > +      pll {
>
> clock-controller? Why can't the parent device be the clk provider and
> have #clock-cells?
>

I don't get your point, sorry. Can you please explain this a bit more
or point to me to an example to understand the real meaning of this?


> > +        compatible = "mediatek,mt7621-clk";
> > +        #clock-cells = <1>;
> > +        clock-output-names = "xtal", "cpu", "bus",
> > +                             "50m", "125m", "150m",
> > +                             "250m", "270m";
> > +      };
> > +    };

Best regards,
    Sergio Paracuellos