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authorMauro Carvalho Chehab <mchehab+huawei@kernel.org>2020-04-15 17:45:19 +0300
committerRob Herring <robh@kernel.org>2020-05-05 01:09:46 +0300
commitafb6120519ae26272946cb4566de5b25fc4f74e0 (patch)
tree3ce63d218ceb59753e2b5100256daafd483eac27 /Documentation/devicetree/changesets.rst
parentb91a770a696ca96a0b8bce9dd39e4f17f2f1d759 (diff)
downloadlinux-afb6120519ae26272946cb4566de5b25fc4f74e0.tar.xz
docs: dt: convert changesets to ReST
- Add a SPDX header; - Add a document title; - Some whitespace fixes and new line breaks; - 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
+
+=============
+DT Changesets
+=============
+
+A DT changeset is a method which allows one to apply changes
+in the live tree in such a way that either the full set of changes
+will be applied, or none of them will be. If an error occurs partway
+through applying the changeset, then the tree will be rolled back to the
+previous state. A changeset can also be removed after it has been
+applied.
+
+When a changeset is applied, all of the changes get applied to the tree
+at once before emitting OF_RECONFIG notifiers. This is so that the
+receiver sees a complete and consistent state of the tree when it
+receives the notifier.
+
+The sequence of a changeset is as follows.
+
+1. of_changeset_init() - initializes a changeset
+
+2. A number of DT tree change calls, of_changeset_attach_node(),
+ of_changeset_detach_node(), of_changeset_add_property(),
+ of_changeset_remove_property, of_changeset_update_property() to prepare
+ a set of changes. No changes to the active tree are made at this point.
+ All the change operations are recorded in the of_changeset 'entries'
+ list.
+
+3. of_changeset_apply() - Apply the changes to the tree. Either the
+ entire changeset will get applied, or if there is an error the tree will
+ be restored to the previous state. The core ensures proper serialization
+ through locking. An unlocked version __of_changeset_apply is available,
+ if needed.
+
+If a successfully applied changeset needs to be removed, it can be done
+with of_changeset_revert().