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

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

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On Thu, Jan 29, 2015 at 09:07:31PM +1100, David Gibson wrote:
> On Wed, Jan 28, 2015 at 08:20:11PM +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-l0cyMroinI0@public.gmane.org>
> 
> Hi, sorry I didn't get around to responding to your earlier posting of
> this.
> 
> The concept is good, and the implementation looks fine.
> 
> Only 2 things before I'm ready to merge:
>   1) It wants a testcase
>   2) I need to stare at the syntax for a while and convince myself
>      it's as good as we can reasonably do.

..and.. #2 is now done.  Give me a testcase, and I'll merge.

-- 
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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