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

[Marek Vasut]

On 6/28/24 10:27 AM, Quentin Schulz wrote:

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 ?

[...]

>>> I am wondering if we cannot simply have a string array with overlays 
>>> applied left-to-right or right-to-left instead? Or u-boot,fdt-dto-N = 
>>> "imx8mp-dhcom-pdk3-overlay-rev100";
>>
>> We can, but that is much harder to test for presence of specific DTO 
>> on U-Boot command line. It is easy to test for presence of boolean or 
>> integer DT property using 'fdt' command.
>>
> 
> Not sure dt-bindings people would love to hear that we adapt the fdt to 
> be easier to work with from the U-Boot CLI :)
> 
> In any case, another few thoughts that popped up overnight:
> 1- do we want to have this for SPL DTB modified by TPL? If so, I'm sure 
> we want it different from the one passed from SPL to U-Boot proper IFF 
> we start from a clean sheet (new DTB) and/or add the DTBO we applied on 
> top the DTBOs already applied by the TPL to the SPL DTB before passing 
> it to proper

As far as I can tell, TPL currently does not support loading fitImages 
and applying DTOs from them. When this is available, I suspect the 
prefix of the newly added property would change from 
u-boot,spl-applied-dto- to u-boot,tpl-applied-dto- and that would be 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 ?