of: base: Improve argument length mismatch error

stable inclusion
from stable-v5.10.94
commit 12224c0d19f34edaca246b99fd79b076b0abadaa
bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=12224c0d19f34edaca246b99fd79b076b0abadaa

--------------------------------

commit 5d05b811 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 72cb4c48 ("arm64: dts: qcom: ipq6018: Fix gpio-ranges
property").
Signed-off-by: NBaruch Siach <baruch@tkos.co.il>
Signed-off-by: NRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/f6a68e0088a552ea9dfd4d8e3b5b586d92594738.1640881913.git.baruch@tkos.co.ilSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>

drivers/of/base.c

@@ -1328,9 +1328,14 @@ int of_phandle_iterator_next(struct of_phandle_iterator *it)
 		 * 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;
 		}
 	}