RTL_W16(CPlusCmd, RTL_R16(CPlusCmd) & ~R8168_CPCMD_QUIRK_MASK);
 
-       rtl_tx_performance_tweak(pdev,
-               (0x5 << MAX_READ_REQUEST_SHIFT) | PCI_EXP_DEVCTL_NOSNOOP_EN);
+       if (tp->dev->mtu <= ETH_DATA_LEN) {
+               rtl_tx_performance_tweak(pdev, (0x5 << MAX_READ_REQUEST_SHIFT) |
+                                        PCI_EXP_DEVCTL_NOSNOOP_EN);
+       }
 }
 
 static void rtl_hw_start_8168bef(struct rtl8169_private *tp)
 
        RTL_W8(Config3, RTL_R8(Config3) & ~Beacon_en);
 
-       rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
+       if (tp->dev->mtu <= ETH_DATA_LEN)
+               rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
 
        rtl_disable_clock_request(pdev);
 
 
        RTL_W8(Config3, RTL_R8(Config3) & ~Beacon_en);
 
-       rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
+       if (tp->dev->mtu <= ETH_DATA_LEN)
+               rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
 
        RTL_W16(CPlusCmd, RTL_R16(CPlusCmd) & ~R8168_CPCMD_QUIRK_MASK);
 }
 
        RTL_W8(MaxTxPacketSize, TxPacketMax);
 
-       rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
+       if (tp->dev->mtu <= ETH_DATA_LEN)
+               rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
 
        RTL_W16(CPlusCmd, RTL_R16(CPlusCmd) & ~R8168_CPCMD_QUIRK_MASK);
 }
 
        RTL_W8(MaxTxPacketSize, TxPacketMax);
 
-       rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
+       if (tp->dev->mtu <= ETH_DATA_LEN)
+               rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
 
        RTL_W16(CPlusCmd, RTL_R16(CPlusCmd) & ~R8168_CPCMD_QUIRK_MASK);
 }
 
        rtl_csi_access_enable_1(tp);
 
-       rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
+       if (tp->dev->mtu <= ETH_DATA_LEN)
+               rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
 
        RTL_W8(MaxTxPacketSize, TxPacketMax);
 
 
        rtl_ephy_init(tp, e_info_8168e_1, ARRAY_SIZE(e_info_8168e_1));
 
-       rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
+       if (tp->dev->mtu <= ETH_DATA_LEN)
+               rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
 
        RTL_W8(MaxTxPacketSize, TxPacketMax);
 
 
        rtl_ephy_init(tp, e_info_8168e_2, ARRAY_SIZE(e_info_8168e_2));
 
-       rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
+       if (tp->dev->mtu <= ETH_DATA_LEN)
+               rtl_tx_performance_tweak(pdev, 0x5 << MAX_READ_REQUEST_SHIFT);
 
        rtl_eri_write(tp, 0xc0, ERIAR_MASK_0011, 0x0000, ERIAR_EXGMAC);
        rtl_eri_write(tp, 0xb8, ERIAR_MASK_0011, 0x0000, ERIAR_EXGMAC);