linux-kernel - Re: [PATCH 4/4] ARM: dts: uniphier: change support card to simple-mfd from simple-bus

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Message-ID: <CAK7LNATFUX56t=wn-3qOSYLwESp63gqDWjADEVQ1g1CYrGxA3g@mail.gmail.com>
Date:   Thu, 25 Jun 2020 23:37:48 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Rob Herring <robh+dt@...nel.org>,
        DTML <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] ARM: dts: uniphier: change support card to simple-mfd
 from simple-bus

On Thu, Jun 25, 2020 at 3:16 AM Lee Jones <lee.jones@...aro.org> wrote:
>
> On Thu, 25 Jun 2020, Masahiro Yamada wrote:
>
> > On Tue, Jun 23, 2020 at 9:24 PM Lee Jones <lee.jones@...aro.org> wrote:
> > >
> > > On Tue, 23 Jun 2020, Masahiro Yamada wrote:
> > >
> > > > 'make ARCH=arm dtbs_check' emits the following warning:
> > > >
> > > >   support-card@1,1f00000: $nodename:0: 'support-card@1,1f00000' does not match '^(bus|soc|axi|ahb|apb)(@[0-9a-f]+)?$'
> > > >
> > > > Maybe, simple-mfd could be a better fit for this device.
> > >
> > > The two should be equivalent.
> >
> > Yes, I know.
> > That's why I can change "simple-bus" to "simple-mfd"
> > with no risk.
> >
> > The difference is schema-check.
> >
> > The node name for "simple-bus" is checked by 'make dtbs_check'.
> >
> > See this code:
> > https://github.com/robherring/dt-schema/blob/v2020.05/schemas/simple-bus.yaml#L17
> >
> > Even if I rename the node, it does not accept the
> > unit name '1,1f00000'
> >
> > > What do you mean by "maybe"?  Does this squash the warning?
> >
> > "maybe" means I am not quite sure
> > which compatible is a better fit
> > to describe this device.
> >
> > As mentioned above, simple-bus and simple-mfd
> > are interchangeable from a driver point of view.
> >
> > This add-on board is integrated with various peripherals
> > such as 16550a serial, smsc9115 ether etc.
> > The address-decode is implemented in a CPLD device.
> > It has chip selects and local addresses, which are mapped to
> > the parent.
> >
> > It can be either simple-bus or simple-mfd, I think.
> >
> >
> > dt-schema checks the node name of simple-bus.
> > Currently, there is no check for simple-mfd.
> >
> > So, I think this patch is an easy solution
> > to fix the warning.
>
> Yes, looking at the documentation it seems as though 'simple-mfd'
> would be a better fit.  Is the device a single IP with various
> different functions?


Not an IP.

This is a small board that consists of
a CPLD + ethernet controller + serial controller + LED, etc.


>
> > Rob is in Cc. Please add comments if any.
> >
> > > Isn't the issue caused by the ','?
> >
> > Right.
> >
> > The node name of simple-bus
> > must meet the regular expression:
> > "^(bus|soc|axi|ahb|apb)(@[0-9a-f]+)?$"
> >
> >
> > Even if I rename the node
> > "support-card@1,1f00000"
> > to "bus@1,1f00000", the warning is still
> > displayed due to ','
> >
> > "1,1f00000" means
> > the address 0x01f00000 of chip select 1.
>
> Is this an officially accepted format?


I am not sure if it is official.

Rob said the data fields should be separated by commas.
https://www.spinics.net/lists/devicetree/msg201565.html




-- 
Best Regards
Masahiro Yamada