linux-kernel - Re: [PATCH v3 1/2] dt-bindings: rng: bcm2835: document reset support

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Message-ID: <c750ae9f6c55011c07868ba563ac8e5af3e01a2a.camel@suse.de>
Date:   Thu, 04 Mar 2021 14:30:59 +0100
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Álvaro Fernández Rojas <noltari@...il.com>
Cc:     Matt Mackall <mpm@...enic.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Rob Herring <robh+dt@...nel.org>,
        Florian Fainelli <f.fainelli@...il.com>,
        Ray Jui <rjui@...adcom.com>,
        Scott Branden <sbranden@...adcom.com>,
        bcm-kernel-feedback-list@...adcom.com,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Mark Brown <broonie@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        "Nícolas "F. R. A. Prado\"" 
        <nfraprado@...tonmail.com>,
        Rikard Falkeborn <rikard.falkeborn@...il.com>,
        Stefan Wahren <stefan.wahren@...e.com>,
        linux-crypto@...r.kernel.org,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>, linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/2] dt-bindings: rng: bcm2835: document reset support

On Thu, 2021-03-04 at 13:18 +0100, Álvaro Fernández Rojas wrote:
> 
> > El 4 mar 2021, a las 13:07, Nicolas Saenz Julienne <nsaenzjulienne@...e.de> escribió:
> > 
> > Hi Alvaro,
> > 
> > On Tue, 2021-02-23 at 18:00 +0100, Álvaro Fernández Rojas wrote:
> > > Some devices may need to perform a reset before using the RNG, such as the
> > > BCM6368.
> > > 
> > > Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> > > ---
> > >  v3: make resets required if brcm,bcm6368-rng.
> > >  v2: document reset support.
> > > 
> > >  .../devicetree/bindings/rng/brcm,bcm2835.yaml   | 17 +++++++++++++++++
> > >  1 file changed, 17 insertions(+)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/rng/brcm,bcm2835.yaml b/Documentation/devicetree/bindings/rng/brcm,bcm2835.yaml
> > > index c147900f9041..11c23e1f6988 100644
> > > --- a/Documentation/devicetree/bindings/rng/brcm,bcm2835.yaml
> > > +++ b/Documentation/devicetree/bindings/rng/brcm,bcm2835.yaml
> > > @@ -37,6 +37,21 @@ required:
> > >  
> > > 
> > > 
> > >  additionalProperties: false
> > 
> > I can't claim I fully understand all the meta stuff in shemas, so I generally
> > just follow the patterns already available out there.
> 
> Well, that makes two of us :).
> 
> > That said, shoudln't this be at the end, just before the examples?
> 
> I don’t know but I can move it there ¯\_(ツ)_/¯

Yes please do. See commit 7f464532b05 ("dt-bindings: Add missing
'additionalProperties: false'") which expands on why it is needed, and why it
should be at the end.

> > Maybe the cause of that odd warning
> > you got there?
> 
> Which odd warning?

The one pointed out by Rob Herring's script, which I can reproduce too BTW. On
the other hand I can't really tell what's wrong right away.

> I don’t get any warnings when running (or at least warnings related to rig, because I get warnings related to other yamls):
> make dt_binding_check DT_SCHEMA_FILES=Documentation/devicetree/bindings/rng/brcm,bcm2835.yaml
> 
> > 
> > > +if:
> > > +  properties:
> > > +    compatible:
> > > +      enum:
> > > +        - brcm,bcm6368-rng
> > > +then:
> > > +  properties:
> > > +    resets:
> > > +      maxItems: 1
> > > +  required:
> > > +    - resets
> > 
> > I belive you can't really make a property required when the bindings for
> > 'brcm,bcm6368-rng' were already defined. This will break the schema for those
> > otherwise correct devicetrees.
> 
> Why not?
> Wouldn’t just be required for brcm,bcm6368-rng?

Well, do all 'brcm,bcm6368-rng' users absolutely need the reset controller? If
so, the original binding is wrong, which should be mentioned and a 'Fixes:' tag
should be added to the commit message. Otherwise, the requirement is optional.

Regards,
Nicolas


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