Re: [PATCH v11 5/7] overlay: Documentation for the overlay sugar syntax

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

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On Mon, Nov 28, 2016 at 08:36:07PM -0800, Frank Rowand wrote:
> On 11/28/16 19:10, David Gibson wrote:
> > On Mon, Nov 28, 2016 at 06:05:39PM +0200, Pantelis Antoniou wrote:
> >> There exists a syntactic sugar version of overlays which
> >> make them simpler to write for the trivial case of a single target.
> 
> It also works for multiple targets.  (See the example I provided in
> my comment to v10.)
> 
> 
> >>
> >> Document it in the device tree object internals.
> >>
> >> Signed-off-by: Pantelis Antoniou <pantelis.antoniou-OWPKS81ov/FWk0Htik3J/w@public.gmane.org>
> > 
> > I'm with Frank that I think this, rather than being regarded mere
> > syntactic sugar, should be considered the primary way of describing
> > overlays.
> > 
> > Obviously we need to support the fully written out version as well.
> 
> If we need to support the fully written out version, can we make that
> a discouraged, non-preferred method?  Maybe require an option to
> enable compiling this style of dts?

Yeah.  To avoid further proliferation of options, I'm thinking a
single "backwards compat" option which would:
	- Use the dtb magic instead of dtb magic
	- Disable checks which would reject explicit creation of
	  __overlay__ / __symbols__ / __fixups__ nodes
	- Anything other special behaviour we need
	
> I can imagine some reasons to support the fully written out version,
> but can we document what those reasons are?

I believe the main one is the dts files in this format out in the
field.  Mind you, I guess we're already requiring them to tweak how
they declare the /plugin/ option.

-- 
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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