From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Warren Subject: Re: "magic" handling of memory nodes Date: Thu, 24 Apr 2014 10:57:03 -0600 Message-ID: <5359425F.9090200@wwwdotorg.org> References: <20140424113311.GR5904@bivouac.eciton.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140424113311.GR5904-t77nlHhSwNqAroYi2ySoxKxOck334EZe@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Leif Lindholm , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org List-Id: devicetree@vger.kernel.org On 04/24/2014 05:33 AM, Leif Lindholm wrote: > Hi, > > Following on the special handling of nodes called memory@0, I went to > have a look at the various platforms that do not actually declare a > device_type = "memory" for their "memory" nodes. > > Firstly, we currently have 162(ish, I did a sloppy grep) such .dts{i} > files in the kernel tree. > > Secondly, the only reason these platforms could ever have worked is > because they include .dtsi files that define a memory node with a > type explicitly set. Since this node already exists, its contents get > overridden, but the type tag remains. Of course, this only happens > with nodes called explicitly "memory" - but it happens regardless of > what other things they contain. That's precisely how DT includes/overrides are supposed to work, and is entirely expected and normal. Since skeleton.dtsi already says: memory { device_type = "memory"; reg = <0 0>; }; ... then any .dts which includes that already has the device_type property set, so there's no need to repeat that property. Subsequent changes to /memory/reg have no impact on /memory/device_type; any new node definitions simply over-write any previous definitions of a redefined property, but leave unmentioned properties unchanged (unless you /delete-property/). If skeleton.dtsi were changed to remove that property then yes a lot of files would then need to set it, but why would it be removed? -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html