Re: [PATCH fixup v1] of: base: register DT root as device

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello,

On 8/12/20 5:13 PM, Oleksij Rempel wrote:
>>> +		dev_set_name(dev, "dt-root.of");
>>
>> Couldn't we drop the dt-? just let it be root.of.
>> dashes make use of device parameters less convenient should we
>> want to use those in future IIRC.
> 
> dt is used to make clear: it is root of dt and not some random root of
> what ever.

It's redundant, there is already a .of suffix.
I like machine.of more though.

>> of_platform_device_create does:
>>
>> [-] check if device is available: not applicable to root node
>> [-] populate io resources: not applicable to root node
>> [-] use of_device_make_bus_id to get a name: not applicable to root node (prior to this patch)
>> [-] configure dma: not applicable to root node
>> [x] call platform_device_register
> 
> You make this assumption, just because this node has no parents?
> Does it means, a parent less child may have no resources to do some work?
> You should be ashamed of yourself! :D
> 
> But really, what prevents you to assign board specific resource to a
> root node. It is just node as many others.

It makes no sense for the root node to have resources.
What is a machine-wide interrupt? Or a machine-wide MMIO region?
What size would that region even have, when you have no parent
bus that defines address/size cells?

Do you have any examples of oftree resources for the root node?

I'd rather not litter core code with an if-clause that evaluates to
true only once, to support your (IMHO wrong) use of a helper.

of_device_make_bus_id is taken from Linux and does per comment:

This routine will first try using the translated bus address to
derive a unique name. If it cannot, then it will prepend names from
parent nodes until a unique name can be derived.

IMO, it should stay that way.

Cheers
Ahmad


> 
> Regards,
> Oleksij
> 

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