Re: [PATCH] ARM: BCM5301X: Enable UART0 for SmartRG SR-400AC

[Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

Le 06/27/15 15:08, Rafał Miłecki a écrit :
> On 24 June 2015 at 01:51, Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
>> Enable the use of UART0 by overriding its default status property.
>>
>> Signed-off-by: Florian Fainelli <f.fainelli-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>  arch/arm/boot/dts/bcm4708-smartrg-sr400ac.dts | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/bcm4708-smartrg-sr400ac.dts b/arch/arm/boot/dts/bcm4708-smartrg-sr400ac.dts
>> index d6a033b97c70..64a5e8ab65e0 100644
>> --- a/arch/arm/boot/dts/bcm4708-smartrg-sr400ac.dts
>> +++ b/arch/arm/boot/dts/bcm4708-smartrg-sr400ac.dts
>> @@ -118,3 +118,7 @@
>>                 };
>>         };
>>  };
>> +
>> +&uart0 {
>> +       status = "okay";
>> +};
> 
> We have many more changes like this in OpenWrt, I just didn't upstream
> them because of current chipcommonA state.
> 
> It was added before we got "brcm,bus-axi" and I believe Hauke wanted
> move it to the "correct" place at some point. Since UART is part of
> ChipCommon device and ChipCommon is part of "brcm,bus-axi",.I guess we
> should add UARTs as a ChipCommon device subnodes. We already have
> chipcommon: chipcommon@0 {
>         reg = <0x00000000 0x1000>;
> 
>         gpio-controller;
>         #gpio-cells = <2>;
> };
> , is it possible to move UARTs there?
> 
> I'm not sure if this UART cleanup should block your change. I guess it
> depends on the way it'll finally look like.

I do not think it will, see below:

> 
> I'm also wondering: is there any preference between overwriting status
> with something like
> &uart0 { };
> and
> chipcommonA {
>     uart0: serial@0300 { };
> };
> ? I don't know DT that well, just asking.

An alias can be located pretty much anywhere in the DTS as long as the
name is unique, which is why I took this approach, because I do not have
to do something like this and need to know the full depth of the tree:

foo0 {
	bar0 {
		baz0 {
			status = "okay";
		};
	};
};

This is both more compact, and more robust to re-parenting the UART0
node in case you ever wanted to do it in the future.

I will happily fix the other DTSes to use that convention if we agree
this is the route to take.

Thanks!
--
Florian
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