Re: [PATCH V2 2/2] arm64: dts: broadcom: add BCM4908 and Asus GT-AC5300 early DTS files

[Florian Fainelli <f.fainelli@gmail.com>]

On 11/10/2020 9:59 PM, Rafał Miłecki wrote:
> On 11.11.2020 02:04, Florian Fainelli wrote:
>>> diff --git a/arch/arm64/boot/dts/broadcom/bcm4908/bcm4908.dtsi
>>> b/arch/arm64/boot/dts/broadcom/bcm4908/bcm4908.dtsi
>>> new file mode 100644
>>> index 000000000000..3bbefc86b978
>>> --- /dev/null
>>> +++ b/arch/arm64/boot/dts/broadcom/bcm4908/bcm4908.dtsi
>>> @@ -0,0 +1,188 @@
>>> +// SPDX-License-Identifier: GPL-2.0-or-later OR MIT
>>> +
>>> +#include <dt-bindings/interrupt-controller/irq.h>
>>> +#include <dt-bindings/interrupt-controller/arm-gic.h>
>>> +
>>> +/dts-v1/;
>>> +
>>> +/ {
>>> +    interrupt-parent = <&gic>;
>>> +
>>> +    #address-cells = <2>;
>>> +    #size-cells = <2>;
>>> +
>>> +    aliases {
>>> +        serial0 = &uart0;
>>> +    };
>>> +
>>> +    chosen {
>>> +        bootargs = "earlycon=bcm63xx_uart,0xff800640";
>>
>> We talked about it before, but the earlycon should be dropped from the
>> .dtsi file, it does not really belong there.
> 
> I asked the following question that you probably missed, could you check
> it, please?
> 
> On Wed, 4 Nov 2020 at 09:02, Rafał Miłecki <zajec5@gmail.com> wrote:
>> Can you explain why, is that some kernel rule I missed? That's
> extremely helpful for debugging.

It's useful for debugging but because it is meant for debugging it does
not really belong in a .dtsi which gets included by a board level .dts
file and I would argue that it does not belong in a board level .dts
either. This is something that you can and should keep locally while
debugging and remove for "production". That is not a rule that is
written somewhere, and there are certainly cases of .dts files in the
kernel containing "earlycon" for better or for worse.
-- 
Florian