[PATCH] spl: fit: List DTOs applied by SPL in U-Boot control DT

[Marek Vasut]

On 7/1/24 10:42 AM, Quentin Schulz wrote:
> Hi Marek,

Hi,

>>>>> Shouldn't this rather be in /config node?
>>>>
>>>> This is what I had there originally, but then I realized that some 
>>>> DTs might not have the /config node in them (or am I mistaken?), so 
>>>> I moved the new properties into the root node, which surely exists.
>>>>
>>>> It also keeps the code simpler, as it doesn't have to fiddle with 
>>>> creation of the /config node if it doesn't exist.
>>>>
>>>
>>> I don't think we should pollute the root node with this. If we want 
>>> to be able to expose this in a proper binding to the upstream DT 
>>> binding repo, I'm not sure this is going to fly :/
>>
>> The other option is to add more code into SPL, that's not great.
>>
>> I can check if /config node exists, and if so, add it there, otherwise 
>> do nothing. That should be some sort of compromise between bloat and 
>> config node. What do you think ?
>>
>> [...]
>>
> 
> Considering that we're trying to have the same DT for U-Boot and Linux 
> kernel in the long run and that `git grep "\s+config {"` returns nothing 
> in dts/upstream/src, I'm not sure this amounts to anything but 
> dead-code? We could also always insert this node as pre/post process of 
> the DT compilation? But I think some people want to reuse the exact same 
> DTB (like, the binary itself) between U-Boot and the Linux kernel.

In my case, the /config node is inserted via *-u-boot.dtsi , I don't 
think those DT extras are going away anytime soon, esp. because of the 
'bootph-*' properties.

> I guess we can start with checking if the /config node exists and we can 
> figure something smarter once we need it?
> 
> [...]
> 
>>> 2- Add info about which DTBOs were applied to the kernel DTB?
>>
>> SPL DTOs or DTOs applied from kernel fitImage ? Or a merging of those ?
> 
> DTOs that U-Boot proper applies to the kernel DTB either via fitimage 
> configs, maybe also via syslinux (via 
> `fdtoverlays`/`devicetree-overlay`) and the like?

Isn't that something that would be better (=more flexible and fixable if 
broken without bootloader update) done in a boot script which could be 
embedded in a fitImage ?