38 lines
1.5 KiB
ReStructuredText
38 lines
1.5 KiB
ReStructuredText
.. 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().
|