linux-kernel - Re: [PATCH 2/3] dt: bindings: add ralink RT2880 resets device tree binding documentation

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Date:   Tue, 5 Oct 2021 08:27:25 -0500
From:   Rob Herring <robh@...nel.org>
To:     Sergio Paracuellos <sergio.paracuellos@...il.com>
Cc:     linux-staging@...ts.linux.dev, John Crispin <john@...ozen.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, Greg KH <gregkh@...uxfoundation.org>,
        NeilBrown <neil@...wn.name>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/3] dt: bindings: add ralink RT2880 resets device tree
 binding documentation

On Mon, Oct 4, 2021 at 1:23 PM Sergio Paracuellos
<sergio.paracuellos@...il.com> wrote:
>
> Hi Rob,
>
> On Mon, Oct 4, 2021 at 8:06 PM Rob Herring <robh@...nel.org> wrote:
> >
> > On Sun, Sep 26, 2021 at 04:59:30PM +0200, Sergio Paracuellos wrote:
> > > Adds device tree binding documentation for resets in the ralink RT2880 SoCs.
> > >
> > > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@...il.com>
> > > ---
> > >  .../bindings/reset/ralink,rt2880-reset.yaml   | 39 +++++++++++++++++++
> > >  1 file changed, 39 insertions(+)
> > >  create mode 100644 Documentation/devicetree/bindings/reset/ralink,rt2880-reset.yaml
> > >
> > > diff --git a/Documentation/devicetree/bindings/reset/ralink,rt2880-reset.yaml b/Documentation/devicetree/bindings/reset/ralink,rt2880-reset.yaml
> > > new file mode 100644
> > > index 000000000000..88eddeb4ee45
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/reset/ralink,rt2880-reset.yaml
> > > @@ -0,0 +1,39 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/reset/ralink,rt2880-reset.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: Ralink RT2880 Reset Controller Device Tree Bindings
> > > +
> > > +maintainers:
> > > +  - Sergio Paracuellos <sergio.paracuellos@...il.com>
> > > +
> > > +description: |
> > > +  Ralink RT2880 reset controller driver which supports the SoC
> > > +  system controller supplied reset registers for the various peripherals
> > > +  of the SoC.
> > > +
> > > +  See also:
> > > +  - dt-bindings/reset/ralink-rt2880.h
> > > +
> > > +properties:
> > > +  compatible:
> > > +    const: ralink,rt2880-reset
> > > +
> > > +  '#reset-cells':
> > > +    const: 1
> > > +
> > > +required:
> > > +  - '#reset-cells'
> > > +  - compatible
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    #include <dt-bindings/reset/ralink-rt2880.h>
> > > +    rstctrl: reset-controller {
> > > +      compatible = "ralink,rt2880-reset";
> > > +      #reset-cells = <1>;
> >
> > How is this h/w controlled? If this is part of a system controller, then
> > it needs to be documented as such. IOW, you need to document the binding
> > for the whole block.
> >
> > Do you really need a child node here? All you need to make a system
> > controller a reset provider is add '#reset-cells' to it.
>
> I am just documenting what is already mainlined (see [0]) in order to
> get mt7621-dts out of staging at some point of my life. What am I
> supposed to do? Should I rewrite all already mainlined code? Because
> if that is the case we need to rewrite tons of things from the ralink
> platform...

On the flip side, am I not supposed to review bindings because the dts
is already in staging? Code dependent on DT bindings shouldn't have
been mainlined without any documented binding.

Looks like the resets are part of "mediatek,mt7621-sysc" to answer my
question. Add a #reset-cell to that node (and binding) and then change
this line to "mediatek,mt7621-sysc":

        reset_dev.of_node = of_find_compatible_node(NULL, NULL,
                                                "ralink,rt2880-reset");

That's the minimal change, but really I would move the reset code to
the clock driver as that is what handles the sysc node.


> I'd also like to know what we should do with those nodes already added
> to the dtsi file that have not got associated compatible driver
> mainlined. Can we just get rid of them?

Yes. Typically dts files start with minimal support.

A dts file in staging is odd. We shouldn't be adding them there.

Rob