netdev - [PATCH] of: of_mdio: count number of regitered phys

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Date:   Mon, 29 Jun 2020 10:26:36 +0300
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <andrew@...n.ch>, <f.fainelli@...il.com>, <hkallweit1@...il.com>,
        <linux@...linux.org.uk>, <robh+dt@...nel.org>,
        <frowand.list@...il.com>
CC:     <netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: [PATCH] of: of_mdio: count number of regitered phys

In case of_mdiobus_register_phy()/of_mdiobus_register_device()
returns -ENODEV for all PHYs in device tree or for all scanned
PHYs there is a chance that of_mdiobus_register() to
return success code although no PHY devices were registered.
Add a counter that increments every time a PHY was registered
to avoid the above scenario.

Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---

Though I haven't encountered the scenario described in commit
message. Just went through this code and seemed to me that it
could be enhanved by checking the number of successfuly
registered devices.

Thank you,
Claudiu Beznea

 drivers/of/of_mdio.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/of/of_mdio.c b/drivers/of/of_mdio.c
index eb84507de28a..bbf1d42d27f8 100644
--- a/drivers/of/of_mdio.c
+++ b/drivers/of/of_mdio.c
@@ -249,7 +249,7 @@ int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
 {
 	struct device_node *child;
 	bool scanphys = false;
-	int addr, rc;
+	int addr, rc, devices = 0;
 
 	if (!np)
 		return mdiobus_register(mdio);
@@ -293,9 +293,11 @@ int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
 				addr);
 		else if (rc)
 			goto unregister;
+		else
+			devices++;
 	}
 
-	if (!scanphys)
+	if (!scanphys && devices)
 		return 0;
 
 	/* auto scan for PHYs with empty reg property */
@@ -319,14 +321,21 @@ int of_mdiobus_register(struct mii_bus *mdio, struct device_node *np)
 				 * scanning should continue.
 				 */
 				rc = of_mdiobus_register_phy(mdio, child, addr);
-				if (!rc)
+				if (!rc) {
+					devices++;
 					break;
+				}
 				if (rc != -ENODEV)
 					goto unregister;
 			}
 		}
 	}
 
+	if (!devices) {
+		rc = -ENODEV;
+		goto unregister;
+	}
+
 	return 0;
 
 unregister:
-- 
2.7.4