diff options
Diffstat (limited to 'Documentation/devicetree')
| -rw-r--r-- | Documentation/devicetree/changesets.txt | 40 | ||||
| -rw-r--r-- | Documentation/devicetree/todo.txt | 11 |
2 files changed, 51 insertions, 0 deletions
diff --git a/Documentation/devicetree/changesets.txt b/Documentation/devicetree/changesets.txt new file mode 100644 index 000000000000..935ba5acc34e --- /dev/null +++ b/Documentation/devicetree/changesets.txt @@ -0,0 +1,40 @@ +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. mutex_lock(of_mutex) - starts a changeset; The global of_mutex +ensures there can only be one editor at a time. + +4. 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 + +5. mutex_unlock(of_mutex) - All operations complete, release the mutex + +If a successfully applied changeset needs to be removed, it can be done +with the following sequence. + +1. mutex_lock(of_mutex) + +2. of_changeset_revert() + +3. mutex_unlock(of_mutex) diff --git a/Documentation/devicetree/todo.txt b/Documentation/devicetree/todo.txt new file mode 100644 index 000000000000..c3cf0659bd19 --- /dev/null +++ b/Documentation/devicetree/todo.txt @@ -0,0 +1,11 @@ +Todo list for devicetree: + +=== General structure === +- Switch from custom lists to (h)list_head for nodes and properties structure +- Remove of_allnodes list and iterate using list of child nodes alone + +=== CONFIG_OF_DYNAMIC === +- Switch to RCU for tree updates and get rid of global spinlock +- Document node lifecycle for CONFIG_OF_DYNAMIC +- Always set ->full_name at of_attach_node() time +- pseries: Get rid of open-coded tree modification from arch/powerpc/platforms/pseries/dlpar.c |