r8169: fix auto speed down issue

commit e2409d8 upstream.

It would cause no link after suspending or shutdowning when the
nic changes the speed to 10M and connects to a link partner which
forces the speed to 100M.

Check the link partner ability to determine which speed to set.

The link speed down code path is not factored in this kernel version.

Signed-off-by: Hayes Wang <hayeswang@realtek.com>
Acked-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/r8169.c

@@ -3105,11 +3105,34 @@ static void r810x_phy_power_up(struct rtl8169_private *tp)
 	rtl_writephy(tp, MII_BMCR, BMCR_ANENABLE);
 }
 
+static void rtl_speed_down(struct rtl8169_private *tp)
+{
+	u32 adv;
+	int lpa;
+
+	rtl_writephy(tp, 0x1f, 0x0000);
+	lpa = rtl_readphy(tp, MII_LPA);
+
+	if (lpa & (LPA_10HALF | LPA_10FULL))
+		adv = ADVERTISED_10baseT_Half | ADVERTISED_10baseT_Full;
+	else if (lpa & (LPA_100HALF | LPA_100FULL))
+		adv = ADVERTISED_10baseT_Half | ADVERTISED_10baseT_Full |
+		      ADVERTISED_100baseT_Half | ADVERTISED_100baseT_Full;
+	else
+		adv = ADVERTISED_10baseT_Half | ADVERTISED_10baseT_Full |
+		      ADVERTISED_100baseT_Half | ADVERTISED_100baseT_Full |
+		      (tp->mii.supports_gmii ?
+		       ADVERTISED_1000baseT_Half |
+		       ADVERTISED_1000baseT_Full : 0);
+
+	rtl8169_set_speed(tp->dev, AUTONEG_ENABLE, SPEED_1000, DUPLEX_FULL,
+			  adv);
+}
+
 static void r810x_pll_power_down(struct rtl8169_private *tp)
 {
 	if (__rtl8169_get_wol(tp) & WAKE_ANY) {
-		rtl_writephy(tp, 0x1f, 0x0000);
-		rtl_writephy(tp, MII_BMCR, 0x0000);
+		rtl_speed_down(tp);
 		return;
 	}
 
@@ -3201,8 +3224,7 @@ static void r8168_pll_power_down(struct rtl8169_private *tp)
 		rtl_ephy_write(ioaddr, 0x19, 0xff64);
 
 	if (__rtl8169_get_wol(tp) & WAKE_ANY) {
-		rtl_writephy(tp, 0x1f, 0x0000);
-		rtl_writephy(tp, MII_BMCR, 0x0000);
+		rtl_speed_down(tp);
 
 		if (tp->mac_version == RTL_GIGA_MAC_VER_32 ||
 		    tp->mac_version == RTL_GIGA_MAC_VER_33)