r6040: check MDIO register busy waiting result

We are currently busy waiting for MDIO registers to complete their
operation but we did not propagate the result back to the caller.
Update r6040_phy_{read,write} to report the busy waiting result
accordingly.
Signed-off-by: NFlorian Fainelli <florian@openwrt.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/rdc/r6040.c

@@ -224,11 +224,14 @@ static int r6040_phy_read(void __iomem *ioaddr, int phy_addr, int reg)
 			break;
 	}
 
+	if (limit < 0)
+		return -ETIMEDOUT;
+
 	return ioread16(ioaddr + MMRD);
 }
 
 /* Write a word data from PHY Chip */
-static void r6040_phy_write(void __iomem *ioaddr,
+static int r6040_phy_write(void __iomem *ioaddr,
 					int phy_addr, int reg, u16 val)
 {
 	int limit = MAC_DEF_TIMEOUT;
@@ -243,6 +246,8 @@ static void r6040_phy_write(void __iomem *ioaddr,
 		if (!(cmd & MDIO_WRITE))
 			break;
 	}
+
+	return (limit < 0) ? -ETIMEDOUT : 0;
 }
 
 static int r6040_mdiobus_read(struct mii_bus *bus, int phy_addr, int reg)
@@ -261,9 +266,7 @@ static int r6040_mdiobus_write(struct mii_bus *bus, int phy_addr,
 	struct r6040_private *lp = netdev_priv(dev);
 	void __iomem *ioaddr = lp->base;
 
-	r6040_phy_write(ioaddr, phy_addr, reg, value);
-
-	return 0;
+	return r6040_phy_write(ioaddr, phy_addr, reg, value);
 }
 
 static int r6040_mdiobus_reset(struct mii_bus *bus)