[PATCH 5.16 0921/1039] of: base: Improve argument length mismatch error

[Greg Kroah-Hartman]

From: Baruch Siach <baruch@xxxxxxxxxx>

commit 5d05b811b5acb92fc581a7b328b36646c86f5ab9 upstream.

The cells_name field of of_phandle_iterator might be NULL. Use the
phandle name instead. With this change instead of:

  OF: /soc/pinctrl@1000000: (null) = 3 found 2

We get:

  OF: /soc/pinctrl@1000000: phandle pinctrl@1000000 needs 3, found 2

Which is a more helpful messages making DT debugging easier.

In this particular example the phandle name looks like duplicate of the
same node name. But note that the first node is the parent node
(it->parent), while the second is the phandle target (it->node). They
happen to be the same in the case that triggered this improvement. See
commit 72cb4c48a46a ("arm64: dts: qcom: ipq6018: Fix gpio-ranges
property").

Signed-off-by: Baruch Siach <baruch@xxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Link: https://lore.kernel.org/r/f6a68e0088a552ea9dfd4d8e3b5b586d92594738.1640881913.git.baruch@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/of/base.c |   11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1349,9 +1349,14 @@ int of_phandle_iterator_next(struct of_p
 		 * property data length
 		 */
 		if (it->cur + count > it->list_end) {
-			pr_err("%pOF: %s = %d found %td\n",
-			       it->parent, it->cells_name,
-			       count, it->list_end - it->cur);
+			if (it->cells_name)
+				pr_err("%pOF: %s = %d found %td\n",
+					it->parent, it->cells_name,
+					count, it->list_end - it->cur);
+			else
+				pr_err("%pOF: phandle %s needs %d, found %td\n",
+					it->parent, of_node_full_name(it->node),
+					count, it->list_end - it->cur);
 			goto err;
 		}
 	}