r8169: fix auto speed down issue

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.
Signed-off-by: NHayes Wang <hayeswang@realtek.com>
Acked-by: NFrancois Romieu <romieu@fr.zoreil.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/realtek/r8169.c

@@ -3818,6 +3818,30 @@ static void rtl_init_mdio_ops(struct rtl8169_private *tp)
 	}
 }
 
+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 rtl_wol_suspend_quirk(struct rtl8169_private *tp)
 {
 	void __iomem *ioaddr = tp->mmio_addr;
@@ -3848,9 +3872,7 @@ static bool rtl_wol_pll_power_down(struct rtl8169_private *tp)
 	if (!(__rtl8169_get_wol(tp) & WAKE_ANY))
 		return false;
 
-	rtl_writephy(tp, 0x1f, 0x0000);
-	rtl_writephy(tp, MII_BMCR, 0x0000);
-
+	rtl_speed_down(tp);
 	rtl_wol_suspend_quirk(tp);
 
 	return true;