[coreboot-gerrit] [XS] Change in coreboot[main]: commonlib/device_tree: Skip dt_read_cell_props() when not needed

[Julius Werner (Code Review)]

Julius Werner has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/85989?usp=email )

Change subject: commonlib/device_tree: Skip dt_read_cell_props() when not needed
......................................................................

commonlib/device_tree: Skip dt_read_cell_props() when not needed

dt_find_node() calls dt_read_cell_props() for every node it walks, but
this is only actually necessary when the caller is interested in the
`#address-cells` and `#size-cells` values and passed out-parameters to
receive them. Most callers don't actually do that, and we scan through
all properties needlessly on every node. This patch adds a fast path to
skip that.

Change-Id: I114f824a7d88b0bac4a96aca3f7dced459503b02
Signed-off-by: Julius Werner 
---
M src/commonlib/device_tree.c
1 file changed, 4 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/89/85989/1

diff --git a/src/commonlib/device_tree.c b/src/commonlib/device_tree.c
index 2ee0316..a7007d9 100644
--- a/src/commonlib/device_tree.c
+++ b/src/commonlib/device_tree.c
@@ -1050,7 +1050,8 @@

/* Update #address-cells and #size-cells for the parent level (cells
       properties always count for the direct children of their node). */
-	dt_read_cell_props(parent, addrcp, sizecp);
+	if (addrcp || sizecp)
+		dt_read_cell_props(parent, addrcp, sizecp);

/* Find the next node in the path, if it exists. */
    list_for_each(node, parent->children, list_node) {
@@ -1135,7 +1136,8 @@

if (path[0] == '/') { /* regular path */
    	if (path[1] == '\0') {	/* special case: "/" is root node */
-			dt_read_cell_props(tree->root, addrcp, sizecp);
+			if (addrcp || sizecp)
+				dt_read_cell_props(tree->root, addrcp, sizecp);
    		return tree->root;
    	}