[PATCH] of_firmware: fix lookup of fpga manager

[Michael Tretter]

The of_parse_phandle() looks for the phandle in the root device tree,
but as np is resolved for the target device tree, the phandle refers to
the target device tree and may return a wrong node in the root tree.

Therefore, we must ensure that we look for the manager-node in the
target device tree and look for the manager with that name.

firmwaremgr_find_by_node already uses the name for the lookup.

Signed-off-by: Michael Tretter <m.tretter at pengutronix.de>
---
 drivers/of/of_firmware.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/drivers/of/of_firmware.c b/drivers/of/of_firmware.c
index 80feb3b90dba..0429875a26c4 100644
--- a/drivers/of/of_firmware.c
+++ b/drivers/of/of_firmware.c
@@ -9,14 +9,32 @@
 static struct firmware_mgr *of_node_get_mgr(struct device_node *np)
 {
 	struct device_node *mgr_node;
+	const __be32 *property;
+	phandle phandle;
+	int size;
 
+	/* Find fpga-mgr phandle, which may be set in a parent fpga-region. */
 	do {
-		mgr_node = of_parse_phandle(np, "fpga-mgr", 0);
-		if (mgr_node)
-			return firmwaremgr_find_by_node(mgr_node);
-	} while ((np = of_get_parent(np)) != NULL);
-
-	return NULL;
+		property = of_get_property(np, "fpga-mgr", &size);
+		if (property && size == sizeof(*property))
+			break;
+	} while ((np = of_get_parent(np)) != NULL &&
+		 of_device_is_compatible(np, "fpga-region"));
+	if (!property)
+		return NULL;
+	phandle = be32_to_cpup(property);
+
+	/*
+	 * The phandle in the np will refer to a device node in the target
+	 * tree, which may differ from the phandle in the root tree. We need
+	 * the name of the target node, as firmwaremgr_find_by_node performs
+	 * the lookup by the node name.
+	 */
+	mgr_node = of_find_node_by_phandle_from(phandle, of_find_root_node(np));
+	if (!mgr_node)
+		return NULL;
+
+	return firmwaremgr_find_by_node(mgr_node);
 }
 
 struct fw_load_entry {
-- 
2.39.2