Subject: Re: [PATCH 5/5] PCI fixes for the MPC8641 Rev 2.0 silicon and Rev 1.02hardware

From: Scott Wood <[email-masked]>
Date: Fri, 18 May 2007 12:52:55 -0500

Timur Tabi wrote:
> Scott Wood wrote:
> 
>> Timur Tabi wrote:
>>
>>> Just being able to delete a given node/property would be enough. 
>>
>>
>> I'd rather have an additive model than a subtractive one.  And it 
>> would not be enough, as you would not be able to have two different 
>> versions of a property with the same name.
> 
> 
> The model would be additive, but the DTB would be subtractive.

I meant additive at the DTB level.

 > After
> all, the nodes have to *exist* in the DTB that's given to U-Boot.

Yes, they exist under the /hwoptions node.

 > After
> U-Boot scans the device tree and evaluates the conditions, it has to 
> remove the nodes that fail.

That's your model.  Mine involves merging a fragment that corresponds to 
an active hwoption, with no complex conditional evaluation or deletion 
of anything from the main tree.

How would you express the alternate setting of phy_type in a subtractive 
model?  You can't have two nodes with the same name and different 
phy_types, and you can't have two phy_type properties in one node.

-Scott