linux-kernel - Re: [PATCH v2 2/5] dt-bindings: gpio: pca95xx: add entry for pcal6534 and PI4IOE5V6534Q

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YxdQv99FoFNx+11c@smile.fi.intel.com>
Date:   Tue, 6 Sep 2022 16:53:03 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Martyn Welch <martyn.welch@...labora.co.uk>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Martyn Welch <martyn.welch@...labora.com>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/5] dt-bindings: gpio: pca95xx: add entry for
 pcal6534 and PI4IOE5V6534Q

On Tue, Sep 06, 2022 at 03:33:34PM +0200, Linus Walleij wrote:
> On Tue, Sep 6, 2022 at 3:20 PM Andy Shevchenko
> <andriy.shevchenko@...el.com> wrote:
> > On Tue, Sep 06, 2022 at 03:08:00PM +0200, Linus Walleij wrote:
> > > On Tue, Sep 6, 2022 at 2:19 PM Andy Shevchenko
> > > <andriy.shevchenko@...el.com> wrote:
> > > > On Tue, Sep 06, 2022 at 09:28:16AM +0100, Martyn Welch wrote:

...

> > > > > +    oneOf:
> > > > > +      - items:
> > > > > +        - const: diodes,pi4ioe5v6534q
> > > > > +        - const: nxp,pcal6534
> > > >
> > > > ^^^
> > > >
> > > > > +      - items:
> > > > > +        - enum:
> > > >
> > > > > +          - nxp,pcal6534
> > > >
> > > > ^^^
> > > >
> > > > Not sure why is this dup?
> > >
> > > No that is how DT compatibles work. One version of the component,
> > > bought from NXP will look like this:
> > >
> > > compatible = "nxp,pcal6534";
> > >
> > > Another version bought from diodes will look like this:
> > >
> > > compatible = "diodes,pi4ioe5v6534q", "nxp,pcal6534";
> > >
> > > Then the drivers are probed matching from left to right,
> > > with the "most compatible" matching first.
> > >
> > > This also answers your question on the implementation.
> >
> > Then I don't understand why the const list above is only for new chips
> > and not for the old one where the same can be applied.
> 
> That's YAML. It's because the const list is the most compact way
> to express two precise items following after each other, and the enum
> list is an implicit list of single-item const:s, as you cannot enum
> tuples.

This makes a lot of sense, thank you for explaining this. Indeed, now I
understand the absence of Diodes in the code.

> > Mysterious ways of DT...
> 
> It's not DT, it's YAML that is mysterious. DT itself is a pretty
> straight-forward
> grammar, while YAML is a meta-grammar describing the DT grammar
> (ML stands for Meta Language).
> 
> All meta languages are mysterious.

Yeah :-)

-- 
With Best Regards,
Andy Shevchenko