[PATCH 2/2] usb: dwc3: drd: Avoid error when extcon is missing

[Sam Protsenko <semen.protsenko@linaro.org>]

If "port" node is missing in PHY controller node, dwc3_get_extcon()
isn't able to find extcon device. This is perfectly fine in case when
"usb-role-switch" or OTG is used, but next misleading error message is
printed in that case, from of_graph_get_remote_node():

    OF: graph: no port node found in /phy@1234abcd

Avoid printing that message by checking if port node exists in PHY node
before calling of_graph_get_remote_node().

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
---
 drivers/usb/dwc3/drd.c | 25 ++++++++++++++++---------
 1 file changed, 16 insertions(+), 9 deletions(-)

diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index 3e1c1aacf002..eaf389d3f3c5 100644
--- a/drivers/usb/dwc3/drd.c
+++ b/drivers/usb/dwc3/drd.c
@@ -441,8 +441,8 @@ static int dwc3_drd_notifier(struct notifier_block *nb,
 static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
 {
 	struct device *dev = dwc->dev;
-	struct device_node *np_phy, *np_conn;
-	struct extcon_dev *edev;
+	struct device_node *np_phy;
+	struct extcon_dev *edev = NULL;
 	const char *name;
 
 	if (device_property_read_bool(dev, "extcon"))
@@ -462,15 +462,22 @@ static struct extcon_dev *dwc3_get_extcon(struct dwc3 *dwc)
 		return edev;
 	}
 
+	/*
+	 * Try to get extcon device from USB PHY controller's "port" node.
+	 * Check if it has the "port" node first, to avoid printing the error
+	 * message from underlying code, as it's a valid case: extcon device
+	 * (and "port" node) may be missing in case of "usb-role-switch" or OTG
+	 * mode.
+	 */
 	np_phy = of_parse_phandle(dev->of_node, "phys", 0);
-	np_conn = of_graph_get_remote_node(np_phy, -1, -1);
+	if (of_graph_is_present(np_phy)) {
+		struct device_node *np_conn;
 
-	if (np_conn)
-		edev = extcon_find_edev_by_node(np_conn);
-	else
-		edev = NULL;
-
-	of_node_put(np_conn);
+		np_conn = of_graph_get_remote_node(np_phy, -1, -1);
+		if (np_conn)
+			edev = extcon_find_edev_by_node(np_conn);
+		of_node_put(np_conn);
+	}
 	of_node_put(np_phy);
 
 	return edev;
-- 
2.27.0