1 .. SPDX-License-Identifier: GPL-2.0 2 3 ===================== 4 Devicetree Changesets 5 ===================== 6 7 A Devicetree changeset is a method which allows one to apply changes 8 in the live tree in such a way that either the full set of changes 9 will be applied, or none of them will be. If an error occurs partway 10 through applying the changeset, then the tree will be rolled back to the 11 previous state. A changeset can also be removed after it has been 12 applied. 13 14 When a changeset is applied, all of the changes get applied to the tree 15 at once before emitting OF_RECONFIG notifiers. This is so that the 16 receiver sees a complete and consistent state of the tree when it 17 receives the notifier. 18 19 The sequence of a changeset is as follows. 20 21 1. of_changeset_init() - initializes a changeset 22 23 2. A number of DT tree change calls, of_changeset_attach_node(), 24 of_changeset_detach_node(), of_changeset_add_property(), 25 of_changeset_remove_property, of_changeset_update_property() to prepare 26 a set of changes. No changes to the active tree are made at this point. 27 All the change operations are recorded in the of_changeset 'entries' 28 list. 29 30 3. of_changeset_apply() - Apply the changes to the tree. Either the 31 entire changeset will get applied, or if there is an error the tree will 32 be restored to the previous state. The core ensures proper serialization 33 through locking. An unlocked version __of_changeset_apply is available, 34 if needed. 35 36 If a successfully applied changeset needs to be removed, it can be done 37 with of_changeset_revert().
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