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authorLinus Torvalds <torvalds@linux-foundation.org>2014-08-14 09:53:39 -0600
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-14 09:53:39 -0600
commitae36e95cf81c98b111b84317adeb358aaffa80e2 (patch)
tree87ef144d3392cca199448117a737c657b7c4663a /Documentation/devicetree
parentcc8a44c671fd3a2c792e9e1f59ea1df52697cc8b (diff)
parent663d3f7c2e5e1b018a4c53277ccfde40329d98ca (diff)
downloadop-kernel-dev-ae36e95cf81c98b111b84317adeb358aaffa80e2.zip
op-kernel-dev-ae36e95cf81c98b111b84317adeb358aaffa80e2.tar.gz
Merge tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux
Pull device tree updates from Grant Likely: "The branch contains the following device tree changes the v3.17 merge window: Group changes to the device tree. In preparation for adding device tree overlay support, OF_DYNAMIC is reworked so that a set of device tree changes can be prepared and applied to the tree all at once. OF_RECONFIG notifiers see the most significant change here so that users always get a consistent view of the tree. Notifiers generation is moved from before a change to after it, and notifiers for a group of changes are emitted after the entire block of changes have been applied Automatic console selection from DT. Console drivers can now use of_console_check() to see if the device node is specified as a console device. If so then it gets added as a preferred console. UART devices get this support automatically when uart_add_one_port() is called. DT unit tests no longer depend on pre-loaded data in the device tree. Data is loaded dynamically at the start of unit tests, and then unloaded again when the tests have completed. Also contains a few bugfixes for reserved regions and early memory setup" * tag 'devicetree-for-linus' of git://git.secretlab.ca/git/linux: (21 commits) of: Fixing OF Selftest build error drivers: of: add automated assignment of reserved regions to client devices of: Use proper types for checking memory overflow of: typo fix in __of_prop_dup() Adding selftest testdata dynamically into live tree of: Add todo tasklist for Devicetree of: Transactional DT support. of: Reorder device tree changes and notifiers of: Move dynamic node fixups out of powerpc and into common code of: Make sure attached nodes don't carry along extra children of: Make devicetree sysfs update functions consistent. of: Create unlocked versions of node and property add/remove functions OF: Utility helper functions for dynamic nodes of: Move CONFIG_OF_DYNAMIC code into a separate file of: rename of_aliases_mutex to just of_mutex of/platform: Fix of_platform_device_destroy iteration of devices of: Migrate of_find_node_by_name() users to for_each_node_by_name() tty: Update hypervisor tty drivers to use core stdout parsing code. arm/versatile: Add the uart as the stdout device. of: Enable console on serial ports specified by /chosen/stdout-path ...
Diffstat (limited to 'Documentation/devicetree')
-rw-r--r--Documentation/devicetree/changesets.txt40
-rw-r--r--Documentation/devicetree/todo.txt11
2 files changed, 51 insertions, 0 deletions
diff --git a/Documentation/devicetree/changesets.txt b/Documentation/devicetree/changesets.txt
new file mode 100644
index 0000000..935ba5a
--- /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 0000000..c3cf065
--- /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
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