r8169: Tx performance tweak helper

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Edward Hsu <edward_hsu@realtek.com.tw>

drivers/net/r8169.c

@@ -2054,12 +2054,20 @@ static void rtl_hw_start_8169(struct net_device *dev)
 	RTL_W16(IntrMask, tp->intr_event);
 }
 
+static void rtl_tx_performance_tweak(struct pci_dev *pdev, u8 force)
+{
+	u8 ctl;
+
+	pci_read_config_byte(pdev, 0x69, &ctl);
+	ctl = (ctl & ~0x70) | force;
+	pci_write_config_byte(pdev, 0x69, ctl);
+}
+
 static void rtl_hw_start_8168(struct net_device *dev)
 {
 	struct rtl8169_private *tp = netdev_priv(dev);
 	void __iomem *ioaddr = tp->mmio_addr;
 	struct pci_dev *pdev = tp->pci_dev;
-	u8 ctl;
 
 	RTL_W8(Cfg9346, Cfg9346_Unlock);
 
@@ -2073,10 +2081,7 @@ static void rtl_hw_start_8168(struct net_device *dev)
 
 	RTL_W16(CPlusCmd, tp->cp_cmd);
 
-	/* Tx performance tweak. */
-	pci_read_config_byte(pdev, 0x69, &ctl);
-	ctl = (ctl & ~0x70) | 0x50;
-	pci_write_config_byte(pdev, 0x69, ctl);
+	rtl_tx_performance_tweak(pdev, 0x50);
 
 	RTL_W16(IntrMitigate, 0x5151);