net: phy: improve auto-neg emulation in swphy

Auto-neg emulation currently doesn't set bit BMCR_ANENABLE in BMCR,
add this. Users will ignore speed and duplex settings in BMCR because
we're emulating auto-neg, therefore we can remove related code.
See also following discussion [0].

[0] https://marc.info/?t=155041784900002&r=1&w=2Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/swphy.c

@@ -19,7 +19,6 @@
 #define MII_REGS_NUM 29
 
 struct swmii_regs {
-	u16 bmcr;
 	u16 bmsr;
 	u16 lpa;
 	u16 lpagb;
@@ -40,16 +39,13 @@ enum {
  */
 static const struct swmii_regs speed[] = {
 	[SWMII_SPEED_10] = {
-		.bmcr  = BMCR_FULLDPLX,
 		.lpa   = LPA_10FULL | LPA_10HALF,
 	},
 	[SWMII_SPEED_100] = {
-		.bmcr  = BMCR_FULLDPLX | BMCR_SPEED100,
 		.bmsr  = BMSR_100FULL | BMSR_100HALF,
 		.lpa   = LPA_100FULL | LPA_100HALF,
 	},
 	[SWMII_SPEED_1000] = {
-		.bmcr  = BMCR_FULLDPLX | BMCR_SPEED1000,
 		.bmsr  = BMSR_ESTATEN,
 		.lpagb = LPA_1000FULL | LPA_1000HALF,
 	},
@@ -57,13 +53,11 @@ static const struct swmii_regs speed[] = {
 
 static const struct swmii_regs duplex[] = {
 	[SWMII_DUPLEX_HALF] = {
-		.bmcr  = ~BMCR_FULLDPLX,
 		.bmsr  = BMSR_ESTATEN | BMSR_100HALF,
 		.lpa   = LPA_10HALF | LPA_100HALF,
 		.lpagb = LPA_1000HALF,
 	},
 	[SWMII_DUPLEX_FULL] = {
-		.bmcr  = ~0,
 		.bmsr  = BMSR_ESTATEN | BMSR_100FULL,
 		.lpa   = LPA_10FULL | LPA_100FULL,
 		.lpagb = LPA_1000FULL,
@@ -118,7 +112,6 @@ int swphy_read_reg(int reg, const struct fixed_phy_status *state)
 {
 	int speed_index, duplex_index;
 	u16 bmsr = BMSR_ANEGCAPABLE;
-	u16 bmcr = 0;
 	u16 lpagb = 0;
 	u16 lpa = 0;
 
@@ -136,7 +129,6 @@ int swphy_read_reg(int reg, const struct fixed_phy_status *state)
 	if (state->link) {
 		bmsr |= BMSR_LSTATUS | BMSR_ANEGCOMPLETE;
 
-		bmcr  |= speed[speed_index].bmcr  & duplex[duplex_index].bmcr;
 		lpa   |= speed[speed_index].lpa   & duplex[duplex_index].lpa;
 		lpagb |= speed[speed_index].lpagb & duplex[duplex_index].lpagb;
 
@@ -149,7 +141,7 @@ int swphy_read_reg(int reg, const struct fixed_phy_status *state)
 
 	switch (reg) {
 	case MII_BMCR:
-		return bmcr;
+		return BMCR_ANENABLE;
 	case MII_BMSR:
 		return bmsr;
 	case MII_PHYSID1: