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From:   Chen-Yu Tsai <wens@csie.org>
Date:   Thu, 18 Jan 2018 22:28:49 +0800
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Subject: Re: [PATCH 1/1] ARM: dts: sunxi: Add Olimex A20-SOM204-EVB board
To:     Maxime Ripard <maxime.ripard@free-electrons.com>
Cc:     Stefan Mavrodiev <stefan@olimex.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Russell King <linux@armlinux.org.uk>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        "moderated list:ARM PORT" <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>,
        linux-sunxi <linux-sunxi@googlegroups.com>
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On Thu, Jan 18, 2018 at 6:07 PM, Maxime Ripard
<maxime.ripard@free-electrons.com> wrote:
> Hi!
>
> On Mon, Jan 15, 2018 at 12:07:34PM +0200, Stefan Mavrodiev wrote:
>> > > +/dts-v1/;
>> > > +#include "sun7i-a20.dtsi"
>> > > +#include "sunxi-common-regulators.dtsi"
>> > > +
>> > > +
>> > > +#include <dt-bindings/gpio/gpio.h>
>> > > +#include <dt-bindings/interrupt-controller/irq.h>
>> > > +#include <dt-bindings/pwm/pwm.h>
>> > > +
>> > > +/ {
>> > > + model = "Olimex A20-SOM204-EVB";
>> > > + compatible = "olimex,a20-olimex-som204-evb", "allwinner,sun7i-a20";
>> > > +
>> > > + aliases {
>> > > +         serial0 = &uart0;
>> > > +         serial1 = &uart4;
>> > > +         serial2 = &uart7;
>> > > +         spi0 = &spi1;
>> > > +         spi1 = &spi2;
>> > > +         ethernet1 = &rtl8723bs;
>> >
>> > ethernet1? if there's a single network interface, it should be
>> > ethernet0.
>>
>> I think this will conflict the gmac alias defined in sun7i-a20.dtsi:
>>
>> aliases {
>>     ethernet0 = &gmac;
>> };
>
> We have that? That's bad, but you're right :)
>
>> > > +         stat {
>> > > +                 label = "a20-som204:green:stat";
>> > > +                 gpios = <&pio 8 0 GPIO_ACTIVE_HIGH>;
>> > > +                 default-state = "on";
>> > > +         };
>> > > +
>> > > +         led1 {
>> > > +                 label = "a20-som204-evb:green:led1";
>> > > +                 gpios = <&pio 8 10 GPIO_ACTIVE_HIGH>;
>> > > +                 default-state = "on";
>> > > +         };
>> > > +
>> > > +         led2 {
>> > > +                 label = "a20-som204-evb:yellow:led2";
>> > > +                 gpios = <&pio 8 11 GPIO_ACTIVE_HIGH>;
>> > > +                 default-state = "on";
>> > > +         };
>> >
>> > You don't have the same prefix between stat and led1/led2. I'm fine
>> > with both, but you should be consistent :)
>>
>> STAT led is on the SOM204 module, while led1/2 on the EVB. Thats why
>> they have different prefix.
>
> Still, the user and the system will see it as a single board, and the
> documentation states that it should be the board name. I'm not quite
> sure what a good rule would be here. Have you looked at how other
> boards dealt with it? Chen-Yu, any opinion on this?

Follow the bindings, I guess? I don't think we (sunxi) have dealt
with modules that have LEDs or anything that needs to be named after
the board.

On a related topic, I don't know if you (Stefan / Olimex) want to split
this into a .dtsi file for the SoM, and a .dts file for the EVB. It might
help your customers? I've tried it previously, and it helps in some ways
when you're matching the files to the schematics. But it is confusing
when you want the big picture. On the other hand, this is not going to
help with supporting different modules on the same baseboard, as the
routing, peripherals and labels likely won't match up. Just my two cents.

ChenYu