Merge branch 'add-mdiobus_modify_changed-helper'

Russell King says:

====================
Add mdiobus_modify_changed() helper

Sean Anderson's recent patch series is introducing more read-write
operations on the MDIO bus that only need to happen if a change is
being made.

We have similar logic in __mdiobus_modify_changed(), but we didn't
add its correponding locked variant mdiobus_modify_changed() as we
had very few users. Now that we are getting more, let's add the
helper.
====================

Link: https://lore.kernel.org/r/YV2UIa2eU+UjmWaE@shell.armlinux.org.ukSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/mdio_bus.c

@@ -926,6 +926,28 @@ int mdiobus_modify(struct mii_bus *bus, int addr, u32 regnum, u16 mask, u16 set)
 }
 EXPORT_SYMBOL_GPL(mdiobus_modify);
 
+/**
+ * mdiobus_modify_changed - Convenience function for modifying a given mdio
+ *	device register and returning if it changed
+ * @bus: the mii_bus struct
+ * @addr: the phy address
+ * @regnum: register number to write
+ * @mask: bit mask of bits to clear
+ * @set: bit mask of bits to set
+ */
+int mdiobus_modify_changed(struct mii_bus *bus, int addr, u32 regnum,
+			   u16 mask, u16 set)
+{
+	int err;
+
+	mutex_lock(&bus->mdio_lock);
+	err = __mdiobus_modify_changed(bus, addr, regnum, mask, set);
+	mutex_unlock(&bus->mdio_lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(mdiobus_modify_changed);
+
 /**
  * mdio_bus_match - determine if given MDIO driver supports the given
  *		    MDIO device

drivers/net/phy/phylink.c

@@ -2596,7 +2596,6 @@ int phylink_mii_c22_pcs_set_advertisement(struct mdio_device *pcs,
 {
 	struct mii_bus *bus = pcs->bus;
 	int addr = pcs->addr;
-	int val, ret;
 	u16 adv;
 
 	switch (interface) {
@@ -2610,32 +2609,12 @@ int phylink_mii_c22_pcs_set_advertisement(struct mdio_device *pcs,
 				      advertising))
 			adv |= ADVERTISE_1000XPSE_ASYM;
 
-		val = mdiobus_read(bus, addr, MII_ADVERTISE);
-		if (val < 0)
-			return val;
-
-		if (val == adv)
-			return 0;
-
-		ret = mdiobus_write(bus, addr, MII_ADVERTISE, adv);
-		if (ret < 0)
-			return ret;
-
-		return 1;
+		return mdiobus_modify_changed(bus, addr, MII_ADVERTISE,
+					      0xffff, adv);
 
 	case PHY_INTERFACE_MODE_SGMII:
-		val = mdiobus_read(bus, addr, MII_ADVERTISE);
-		if (val < 0)
-			return val;
-
-		if (val == 0x0001)
-			return 0;
-
-		ret = mdiobus_write(bus, addr, MII_ADVERTISE, 0x0001);
-		if (ret < 0)
-			return ret;
-
-		return 1;
+		return mdiobus_modify_changed(bus, addr, MII_ADVERTISE,
+					      0xffff, 0x0001);
 
 	default:
 		/* Nothing to do for other modes */

include/linux/mdio.h

@@ -349,6 +349,8 @@ int mdiobus_write(struct mii_bus *bus, int addr, u32 regnum, u16 val);
 int mdiobus_write_nested(struct mii_bus *bus, int addr, u32 regnum, u16 val);
 int mdiobus_modify(struct mii_bus *bus, int addr, u32 regnum, u16 mask,
 		   u16 set);
+int mdiobus_modify_changed(struct mii_bus *bus, int addr, u32 regnum,
+			   u16 mask, u16 set);
 
 static inline u32 mdiobus_c45_addr(int devad, u16 regnum)
 {