...
};
-Figure 1, describes a generic structure of machine’s un-flattened device tree
+Figure 1, describes a generic structure of machine's un-flattened device tree
considering only child and sibling pointers. There exists another pointer,
*parent, that is used to traverse the tree in the reverse direction. So, at
a particular level the child node and all the sibling nodes will have a parent
-pointer pointing to a common node (e.g. child1, sibling2, sibling3, sibling4’s
+pointer pointing to a common node (e.g. child1, sibling2, sibling3, sibling4's
parent points to root node)
-root (‘/’)
+root ('/')
|
child1 -> sibling2 -> sibling3 -> sibling4 -> null
| | | |
__dtb_testcases_begin - address marking the start of test data blob
__dtb_testcases_end - address marking the end of test data blob
-Secondly, it calls of_fdt_unflatten_device_tree() to unflatten the flattened
-blob. And finally, if the machine’s device tree (i.e live tree) is present,
+Secondly, it calls of_fdt_unflatten_tree() to unflatten the flattened
+blob. And finally, if the machine's device tree (i.e live tree) is present,
then it attaches the unflattened test data tree to the live tree, else it
attaches itself as a live device tree.
live tree as explained below. To explain the same, the test data tree described
in Figure 2 is attached to the live tree described in Figure 1.
-root (‘/’)
+root ('/')
|
testcase-data
|
Figure 2: Example test data tree to be attached to live tree.
-According to the scenario above, the live tree is already present so it isn’t
-required to attach the root(‘/’) node. All other nodes are attached by calling
+According to the scenario above, the live tree is already present so it isn't
+required to attach the root('/') node. All other nodes are attached by calling
of_attach_node() on each node.
In the function of_attach_node(), the new node is attached as the child of the
data node is attached to the live tree above (Figure 1), the final structure is
as shown in Figure 3.
-root (‘/’)
+root ('/')
|
testcase-data -> child1 -> sibling2 -> sibling3 -> sibling4 -> null
| | | | |
null
-----------------------------------------------------------------------
-root (‘/’)
+root ('/')
|
testcase-data -> child1 -> sibling2 -> sibling3 -> sibling4 -> null
| | | | |
as mentioned above.
If a duplicate node is found (i.e. if a node with same full_name property is
-already present in the live tree), then the node isn’t attached rather its
-properties are updated to the live tree’s node by calling the function
+already present in the live tree), then the node isn't attached rather its
+properties are updated to the live tree's node by calling the function
update_node_properties().
of_detach_node() to detach the nodes from the live device tree.
To detach a node, of_detach_node() first updates all_next linked list, by
-attaching the previous node’s allnext to current node’s allnext pointer. And
-then, it either updates the child pointer of given node’s parent to its
-sibling or attaches the previous sibling to the given node’s sibling, as
+attaching the previous node's allnext to current node's allnext pointer. And
+then, it either updates the child pointer of given node's parent to its
+sibling or attaches the previous sibling to the given node's sibling, as
appropriate. That is it :)