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- .. SPDX-License-Identifier: GPL-2.0
- =====================
- Devicetree Changesets
- =====================
- A Devicetree 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().
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