linux-kernel - [RFC PATCH 07/77] livetree: Improve get_node_by

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Message-ID: <20260112142009.1006236-8-herve.codina@bootlin.com>
Date: Mon, 12 Jan 2026 15:18:57 +0100
From: Herve Codina <herve.codina@...tlin.com>
To: David Gibson <david@...son.dropbear.id.au>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>
Cc: Ayush Singh <ayush@...gleboard.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	devicetree-compiler@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	devicetree-spec@...r.kernel.org,
	Hui Pu <hui.pu@...ealthcare.com>,
	Ian Ray <ian.ray@...ealthcare.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
	Herve Codina <herve.codina@...tlin.com>
Subject: [RFC PATCH 07/77] livetree: Improve get_node_by_phandle()

get_node_by_phandle() allows to get a node based on its phandle value.
It checks the phandle value against value available in internal node
structure.

This internal phandle value is updated during process_check() and so,
get_node_by_phandle() cannot give correct results before the
process_check() call.

Improve get_node_by_phandle() to look at node phandle properties when
the internal phandle value is not valid.

This allows to return a correct matching node even if process_check()
was not called yet.

With the recently introduced FDT_REF_LOCAL dtb tag, this will be needed
to update internal phandle references before the call to process_check().
Indeed, this tag allows to identify phandles and internal references
need to be updated based on the phandle value before the
process_check() call.

Signed-off-by: Herve Codina <herve.codina@...tlin.com>
---
 livetree.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/livetree.c b/livetree.c
index f328824..9b67934 100644
--- a/livetree.c
+++ b/livetree.c
@@ -609,16 +609,35 @@ struct node *get_node_by_label(struct node *tree, const char *label)
 	return NULL;
 }
 
+static cell_t get_node_phandle_existing(struct node *node)
+{
+	struct property *prop;
+
+	if (phandle_is_valid(node->phandle))
+		return node->phandle;
+
+	prop = get_property(node, "phandle");
+	if (!prop) {
+		prop = get_property(node, "linux,phandle");
+		if (!prop)
+			return 0;
+	}
+
+	return propval_cell(prop);
+}
+
 struct node *get_node_by_phandle(struct node *tree, cell_t phandle)
 {
 	struct node *child, *node;
+	cell_t tree_phandle;
 
 	if (!phandle_is_valid(phandle)) {
 		assert(generate_fixups);
 		return NULL;
 	}
 
-	if (tree->phandle == phandle) {
+	tree_phandle = get_node_phandle_existing(tree);
+	if (phandle_is_valid(tree_phandle) && tree_phandle == phandle) {
 		if (tree->deleted)
 			return NULL;
 		return tree;
-- 
2.52.0