[U-Boot] [PATCH 11/13] arm: zynq: dts: Add U-Boot device tree additions

Masahiro Yamada
2015-09-01T16:19:55Z

Hi.

2015-09-02 0:41 GMT+09:00 Michal Simek <monstr@monstr.eu>:

>>>
>>>>
>>>>> Why not just add one more uboot property to chosen with list of IPs
>>>>> which needs to be relocated?
>>>>
>>>> You mean a list of devices needed before relocation?
>>>
>>> I mean something like this:
>>>
>>> chosen {
>>> u-boot,dm-pre-reloc = <&uart1 ...>;
>>> }
>>>
>>> And then just go through this list. I expect that you are looking for
>>> that property anyway.
>>
>> In this case wouldn't it need to list the simple-bus also?
>
> yes for zc702 case
>
> u-boot,dm-pre-reloc = <&amba &uart1>;

I think this should be

u-boot,dm-pre-reloc = &amba, &uart1;

<&label> is used for phandle, while &label is replaced with a string
standing for the full path for the node.

For example, stdout-path takes that:

stdout-path = &serial0;

>
>>
>> We also use this with fdtgrep to remove nodes not needed for SPL. So
>> we would have to come up with a tool to make that work. At present
>> 'fdtgrep -p u-boot,dm-pre-reloc' picks out all the nodes we want (it
>> finds nodes with that property).
>>
>> I'm actually not sure that this approach is any easier/better. What
>> are the advantages?
>
> The question is if current solution which you are using is fully
> compatible with binding. Adding bootloader property to the HW node
> doesn't look like a best solution.
> On the other hand chosen node is the location where OS specific
> properties are coming that's why I have suggested to use it.

I like Michal's idea.
We need some work for fdtgrep, but I believe it is worthwhile.

From Michal's recent patches (http://patchwork.ozlabs.org/patch/498609/),
I guess he is tackling on syncing device trees between Linux and U-boot,
and this is right thing to do.

Inserting the U-boot specific property here and there
makes it difficult.

--
Best Regards
Masahiro Yamada