Re: [PATCH v2] dtc: parser: Add label while overriding nodes

[David Gibson <david@gibson.dropbear.id.au>]

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On Fri, Feb 20, 2015 at 02:11:02AM +0530, Nikhil Devshatwar wrote:
> This patch changes the dtc grammar to allow following syntax
> 
> i2cexp: &i2c2 {
>     ...
> };
> 
> Current device tree compiler allows to define multiple labels when defining
> the device node the first time. Typically device nodes are defined in
> DTSI files. Now these nodes can be overwritten for updating some of the
> properties. Typically, device nodes are overridden in DTS files.
> 
> When working with adapter boards, most of the time adapter board can fit to
> multiple base boards. But depending on which base board it is connected to,
> the devices on the adapter board would be children of different devices.
> 
> e.g. On dra7-evm.dts, i2c2 is exported for expansion connector whereas
> on dra72-evm.dts, i2c5 is exported for expansion connector.
> This causes a problem when writing a generic device tree file for
> the adapter board. Because, you cannot know whether all the devices on
> adapter board are present on i2c or i2c5.
> 
> The problem can be solved by adding a common label (e.g. i2cexp) in both
> of the DTS files when overriding the device nodes for i2c2 or i2c5.
> This way, generic adapter board file would override the i2cexp. And
> depending on which base board you use the adapter board, all the devices
> are automatically added for correct device nodes.
> 
> Signed-off-by: Nikhil Devshatwar <nikhil.nd@ti.com>

Applied, thanks.

I did tweak the testcase to use dtbs_unordered_equal instead of going
through the set of tree1 tests.

The fact that you can only apply a single label by this method is a
bit of a wart, but it's something we can fix later.  I had a look at
it and (as I suspect you already discovered) it's surprisingly
complicated to do so.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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