From: David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>
To: Stuart Yoder <stuart.yoder-3arQi8VN3Tc@public.gmane.org>
Cc: Neil Armstrong
<narmstrong-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>,
"devicetree-spec-u79uwXL29TY76Z2rM5mHXA@public.gmane.org"
<devicetree-spec-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
Subject: Re: Node names and properties names collision
Date: Fri, 13 May 2016 22:17:55 +0100 [thread overview]
Message-ID: <20160513211755.GA6799@littlecatz> (raw)
In-Reply-To: <HE1PR04MB1641C4DB11CDF2618E27BEF18D730-6LN7OEpIatU5tNmRkpaxD89NdZoXdze2vxpqHgZTriW3zl9H0oFU5g@public.gmane.org>
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On Thu, May 12, 2016 at 04:22:39PM +0000, Stuart Yoder wrote:
>
>
> > -----Original Message-----
> > From: devicetree-spec-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org [mailto:devicetree-spec-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org] On Behalf Of
> > Neil Armstrong
> > Sent: Thursday, May 12, 2016 2:40 AM
> > To: devicetree-spec-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> > Subject: Node names and properties names collision
> >
> > Hi,
> >
> > I'm working on a full python device tree library to load blobs and manipulate the tree in-memory as an
> > object tree (http://github.com/superna9999/pyfdt).
> > My testsuite strategy was to run the DTC testsuite and load every DTC generated dtbs, re-generate a DTS
> > and compare the DTC dtb-to-dts output.
> >
> > But I have a strange case using the Amlogic out-of-tree BSP dts where they use the same name for a sub-
> > node and a property :
> >
> > efusekey:efusekey{
> > keynum = <4>;
> > key0 = <&key0>;
> > key1 = <&key1>;
> > key2 = <&key2>;
> > key3 = <&key3>;
> > key0:key0{
> > keyname = "mac";
> > offset = <0>;
> > size = <6>;
> > };
> > key1:key1{
> > keyname = "mac_bt";
> > offset = <6>;
> > size = <6>;
> > };
> > key2:key2{
> > keyname = "mac_wifi";
> > offset = <12>;
> > size = <6>;
> > };
> > key3:key3{
> > keyname = "usid";
> > offset = <18>;
> > size = <16>;
> > };
> > };
> >
> > While reading the original ePAPR and the new linaro specifications, I was not able to find an answer....
> >
> > Is it authorized ? Could this be clarified in the new specifications ?
>
> Nodes and properties can inherently be differentiated, so there should be
> no ambiguity if they happen to have the same name.
Yes, it's permitted. Properties and subnodes of a node live in
different logical namespaces.
> That being said, in practice
> I don't think this situation happens.
It's rare, but it has occurred in practice. A number of old PowerMac
machines had DTs with (IIRC it was both an "l2-cache" property and
"l2-cache" subnode under the cpu nodes).
> A device tree describes hardware. A node
> name "should describe the general class of the device". Property names
> should be meaninful and if they are non-standard should have a organization
> specific prefix.
>
> The DTS example above seems to be a horrible example and follows none of those conventions.
> There are no compatible strings, the node names don't seem to be describing
> hardware. And not sure why you would need properties pointing to subnodes. So,
> the syntax/semantics of device tree allows it, but nothing like that example would
> ever pass a public review.
That particular example does indeed look horrible.
--
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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prev parent reply other threads:[~2016-05-13 21:17 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-12 7:40 Node names and properties names collision Neil Armstrong
[not found] ` <57343365.6080000-rdvid1DuHRBWk0Htik3J/w@public.gmane.org>
2016-05-12 16:22 ` Stuart Yoder
[not found] ` <HE1PR04MB1641C4DB11CDF2618E27BEF18D730-6LN7OEpIatU5tNmRkpaxD89NdZoXdze2vxpqHgZTriW3zl9H0oFU5g@public.gmane.org>
2016-05-13 21:17 ` David Gibson [this message]
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