Thread (1 message) 1 message, 1 author, 2014-01-21

[RFC PATCH 1/1] of/irq: create interrupts-extended-2 property

From: David Gibson <hidden>
Date: 2014-01-21 08:57:50
Also in: linux-devicetree

On Mon, Jan 20, 2014 at 05:03:23PM -0800, Olof Johansson wrote:
On Mon, Jan 20, 2014 at 2:47 PM, Grant Likely [off-list ref] wrote:
quoted
On Wed, 15 Jan 2014 16:12:24 +0000, Mark Rutland [off-list ref] wrote:
quoted
quoted
Another, more invasive option would be extend the dts syntax and teach
dtc to handle property appending. Then the soc dts could stay as it is,
and the board dts could have something like:

    /append-property/ interrupts = <&intc1 6 1>;
    /append-property/ interrupt-names = "board-specific-irq";

Both these options solve the issue at the source, are general to other
properties, and allow more than one level of hierarchy (the proposed
interrupts-extended-2 only allows one level).
I've just had a go at implementing the append-property mechanism above
in dtc, and it was far easier than I expected (patch below).

Does anyone have any issues with the /append-property/ idea?
I think that is reasonable.

The main problem with this (same for clocks) is if you need to append
something with a name when the original didn't have any.

Reordering entries might not work for interrupts, since the bindings
might have requirements on order.

I'm not aware of a good solution for this. Suggestions welcome.
So, in principle my preferred way to handle things like this would be
to add richer expression support, including a token for "previous
value" when overlaying.

But although I've recently had another look at it, that's still a ways
off, so I wouldn't object to another approach as a stopgap, as long as
its not too hideous.

-- 
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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