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authorMauro Carvalho Chehab <mchehab+huawei@kernel.org>2020-04-15 17:45:20 +0300
committerRob Herring <robh@kernel.org>2020-05-05 01:09:52 +0300
commit26853a242057b8c09f51726b54a79aff3fec874a (patch)
tree607967f930e62cd19275903891ccc0eb4761c3d6 /Documentation/devicetree/dynamic-resolution-notes.rst
parentafb6120519ae26272946cb4566de5b25fc4f74e0 (diff)
downloadlinux-26853a242057b8c09f51726b54a79aff3fec874a.tar.xz
docs: dt: convert dynamic-resolution-notes.txt to ReST
- Add a SPDX header; - Adjust document title; - Add it to devicetree/index.rst. Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Signed-off-by: Rob Herring <robh@kernel.org>
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+.. SPDX-License-Identifier: GPL-2.0
+
+==================================
+Device Tree Dynamic Resolver Notes
+==================================
+
+This document describes the implementation of the in-kernel
+Device Tree resolver, residing in drivers/of/resolver.c
+
+How the resolver works
+----------------------
+
+The resolver is given as an input an arbitrary tree compiled with the
+proper dtc option and having a /plugin/ tag. This generates the
+appropriate __fixups__ & __local_fixups__ nodes.
+
+In sequence the resolver works by the following steps:
+
+1. Get the maximum device tree phandle value from the live tree + 1.
+2. Adjust all the local phandles of the tree to resolve by that amount.
+3. Using the __local__fixups__ node information adjust all local references
+ by the same amount.
+4. For each property in the __fixups__ node locate the node it references
+ in the live tree. This is the label used to tag the node.
+5. Retrieve the phandle of the target of the fixup.
+6. For each fixup in the property locate the node:property:offset location
+ and replace it with the phandle value.