r8169: fix performance regression related to PCIe max read request size

It turned out that on low performance systems the original change can
cause lower tx performance. On a N3450-based mini-PC tx performance
in iperf3 was reduced from 950Mbps to ~900Mbps. Therefore effectively
revert the original change, just use pcie_set_readrq() now instead of
changing the PCIe capability register directly.

Fixes: 8458013c81bf ("r8169: remove fiddling with the PCIe max read request size")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index aaa316be6183ca69f85d2871a8b342ab5398ab84..a2168a14794c74c80988b677e2f9cdee59bc4f39 100644 (file)
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -2477,15 +2477,18 @@ static void rtl_hw_jumbo_enable(struct rtl8169_private *tp)
        switch (tp->mac_version) {
        case RTL_GIGA_MAC_VER_12:
        case RTL_GIGA_MAC_VER_17:
+               pcie_set_readrq(tp->pci_dev, 512);
                r8168b_1_hw_jumbo_enable(tp);
                break;
        case RTL_GIGA_MAC_VER_18 ... RTL_GIGA_MAC_VER_26:
+               pcie_set_readrq(tp->pci_dev, 512);
                r8168c_hw_jumbo_enable(tp);
                break;
        case RTL_GIGA_MAC_VER_27 ... RTL_GIGA_MAC_VER_28:
                r8168dp_hw_jumbo_enable(tp);
                break;
        case RTL_GIGA_MAC_VER_31 ... RTL_GIGA_MAC_VER_33:
+               pcie_set_readrq(tp->pci_dev, 512);
                r8168e_hw_jumbo_enable(tp);
                break;
        default:
@@ -2515,6 +2518,9 @@ static void rtl_hw_jumbo_disable(struct rtl8169_private *tp)
                break;
        }
        rtl_lock_config_regs(tp);
+
+       if (pci_is_pcie(tp->pci_dev) && tp->supports_gmii)
+               pcie_set_readrq(tp->pci_dev, 4096);
 }
 
 static void rtl_jumbo_config(struct rtl8169_private *tp, int mtu)