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commonlib/device_tree: Skip dt_read_cell_props() when not needed

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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 <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/85989
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Maximilian Brune <maximilian.brune@9elements.com>
This commit is contained in:
Julius Werner 2025-01-14 13:58:42 -08:00
commit cd912cf4a1
1 changed files with 4 additions and 2 deletions
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6
src/commonlib/device_tree.c
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@ -1050,7 +1050,8 @@ static struct device_tree_node *_dt_find_node(struct device_tree_node *parent,
/* 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 @@ struct device_tree_node *dt_find_node_by_path(struct device_tree *tree,
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;
}