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

From: Masahiro Yamada <masahiroy@kernel.org>
To: Lee Jones <lee.jones@linaro.org>
Cc: linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Rob Herring <robh+dt@kernel.org>,
	DTML <devicetree@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/4] ARM: dts: uniphier: change support card to simple-mfd from simple-bus
Date: Thu, 25 Jun 2020 01:29:04 +0900	[thread overview]
Message-ID: <CAK7LNAR-dm6Zbtt9MsUunn9+qqwTtRCbq4Wzb=8uKLtfaLK6TQ@mail.gmail.com> (raw)
In-Reply-To: <20200623122413.GA954398@dell>

On Tue, Jun 23, 2020 at 9:24 PM Lee Jones <lee.jones@linaro.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.

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.

Thanks

>
> > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> > ---
> >
> >  arch/arm/boot/dts/uniphier-support-card.dtsi | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/boot/dts/uniphier-support-card.dtsi b/arch/arm/boot/dts/uniphier-support-card.dtsi
> > index 11e46e7de7c5..eedc10cbc6e6 100644
> > --- a/arch/arm/boot/dts/uniphier-support-card.dtsi
> > +++ b/arch/arm/boot/dts/uniphier-support-card.dtsi
> > @@ -10,7 +10,7 @@ &system_bus {
> >       ranges = <1 0x00000000 0x42000000 0x02000000>;
> >
> >       support_card: support-card@1,1f00000 {
> > -             compatible = "simple-bus";
> > +             compatible = "simple-mfd";
> >               #address-cells = <1>;
> >               #size-cells = <1>;
> >               ranges = <0x00000000 1 0x01f00000 0x00100000>;
>
> --
> Lee Jones [李琼斯]
> Senior Technical Lead - Developer Services
> Linaro.org │ Open source software for Arm SoCs
> Follow Linaro: Facebook | Twitter | Blog

--
Best Regards
Masahiro Yamada