is there any value in unreferenced <linux,phandle> assignments?

is there any value in unreferenced <linux,phandle> assignments?

[Robert P. J. Day]

  apologies for what i'm sure is a trivial question, but is there any
point in a .dts file having "linux,phandle" assignments that are
unreferenced from anywhere in the final source file?

  i ask only because i've been handed a .dts file that admittedly
works just fine, but it contains a number of lines of the form:

  linux,phandle = <some-number>;

where none of those numeric phandles are referenced from anywhere else
in the source file (even after processing any .dtsi files).

  one possibility is that those are leftovers before someone started
adding labels to nodes, and referring to them like that, but in my
case, the nodes defining those phandles don't even have labels, so
that seems fairly pointless.

  is there any other explanation for them? thanks.

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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Re: is there any value in unreferenced <linux,phandle> assignments?

[Mark Rutland]

On Tue, May 24, 2016 at 06:49:40AM -0400, Robert P. J. Day wrote:
> 
>   apologies for what i'm sure is a trivial question, but is there any
> point in a .dts file having "linux,phandle" assignments that are
> unreferenced from anywhere in the final source file?
> 
>   i ask only because i've been handed a .dts file that admittedly
> works just fine, but it contains a number of lines of the form:
> 
>   linux,phandle = <some-number>;
> 
> where none of those numeric phandles are referenced from anywhere else
> in the source file (even after processing any .dtsi files).
> 
>   one possibility is that those are leftovers before someone started
> adding labels to nodes, and referring to them like that, but in my
> case, the nodes defining those phandles don't even have labels, so
> that seems fairly pointless.
> 
>   is there any other explanation for them? thanks.

It sounds like the dts file has been decompiled from a DTB, which would
explain the lack of labels. Otherwise, the phandle and linux,phandle
properties are generally not expected to be set directly in a dts
(though this is possible).

I suspect that there were unreferenced labels in the origninal
dts/dtsi, as I believe dtc adds a phandle for any label, regardless of
whether it is referenced (though I could be wrong).

Thanks,
Mark.
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Re: is there any value in unreferenced <linux,phandle> assignments?

[Robert P. J. Day]

On Tue, 24 May 2016, Mark Rutland wrote:

> On Tue, May 24, 2016 at 06:49:40AM -0400, Robert P. J. Day wrote:
> >
> >   apologies for what i'm sure is a trivial question, but is there
> > any point in a .dts file having "linux,phandle" assignments that
> > are unreferenced from anywhere in the final source file?
> >
> >   i ask only because i've been handed a .dts file that admittedly
> > works just fine, but it contains a number of lines of the form:
> >
> >   linux,phandle = <some-number>;
> >
> > where none of those numeric phandles are referenced from anywhere
> > else in the source file (even after processing any .dtsi files).
> >
> >   one possibility is that those are leftovers before someone
> > started adding labels to nodes, and referring to them like that,
> > but in my case, the nodes defining those phandles don't even have
> > labels, so that seems fairly pointless.
> >
> >   is there any other explanation for them? thanks.
>
> It sounds like the dts file has been decompiled from a DTB, ...

  ah, suddenly it makes perfect sense, thanks.

rday

-- 

========================================================================
Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
========================================================================

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