linux-kernel - [PATCH v3 2/2] usb: dwc3: drd: Improve dwc3_get

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Message-Id: <20201211211916.6259-3-semen.protsenko@linaro.org>
Date:   Fri, 11 Dec 2020 23:19:16 +0200
From:   Sam Protsenko <semen.protsenko@...aro.org>
To:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        John Stultz <john.stultz@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v3 2/2] usb: dwc3: drd: Improve dwc3_get_extcon() style

Commit c73b41955ee4 ("usb: dwc3: drd: Avoid error when extcon is
missing") changed the code flow in dwc3_get_extcon() function, leading
to unnecessary if-branch. This patch does housekeeping by reworking the
code for obtaining extcon device from the "port" node. While at it, add
the  comment from mentioned code block, explaining how checking the port
availability helps to avoid the misleading error.

Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
Changes in v3:
  - Split patch into two patches: logic diff and style diff

 drivers/usb/dwc3/drd.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/dwc3/drd.c b/drivers/usb/dwc3/drd.c
index 312a4d060e80..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"))
@@ -462,18 +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);
-	if (of_graph_is_present(np_phy))
-		np_conn = of_graph_get_remote_node(np_phy, -1, -1);
-	else
-		np_conn = NULL;
+	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;
-- 
2.29.2