RE: [PATCH net-next 2/2] r8169: enable LTR support

We generally do not recommend disabling LTR. LTR works in concert
with ASPM to reduce power consumption while maintaining performance.
There is no LTR-related bug in the existing code. The issue observed
on the customer���s evaluation platform is that the link cannot enter
L1.1/L1.2 without LTR support. This patch enables LTR to allow the
device and platform to reach those low power states. Therefore, this
patch should be considered as a new feature.
After a hardware reset, LTR Enable defaults to 0 (disabled). Driver
must program the related registers to enable LTR.
We will replace some register numbers with names according to the
datasheet in the next patch.

quoted

Signed-off-by: Javen Xu <redacted>
---
 drivers/net/ethernet/realtek/r8169_main.c | 98 
+++++++++++++++++++++++
 1 file changed, 98 insertions(+)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c 

b/drivers/net/ethernet/realtek/r8169_main.c
index f9df6aadacce..97abf95502dc 100644

--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c

@@ -2919,6 +2919,101 @@ static void rtl_disable_exit_l1(struct rtl8169_private *tp)
      }
 }

+static void rtl_enable_ltr(struct rtl8169_private *tp) {
+     switch (tp->mac_version) {
+     case RTL_GIGA_MAC_VER_80:
+             r8168_mac_ocp_write(tp, 0xcdd0, 0x9003);
+             r8168_mac_ocp_modify(tp, 0xe034, 0x0000, 0xc000);
+             r8168_mac_ocp_modify(tp, 0xe0a2, 0x0000, BIT(0));
+             r8168_mac_ocp_write(tp, 0xcdd2, 0x8c09);
+             r8168_mac_ocp_write(tp, 0xcdd8, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdd4, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdda, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdd6, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcddc, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcde8, 0x887a);
+             r8168_mac_ocp_write(tp, 0xcdea, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdec, 0x8c09);
+             r8168_mac_ocp_write(tp, 0xcdee, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdf0, 0x8a62);
+             r8168_mac_ocp_write(tp, 0xcdf2, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdf4, 0x883e);
+             r8168_mac_ocp_write(tp, 0xcdf6, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdf8, 0x8849);
+             r8168_mac_ocp_write(tp, 0xcdfa, 0x9003);
+             r8168_mac_ocp_modify(tp, 0xe032, 0x0000, BIT(14));
+             break;
+     case RTL_GIGA_MAC_VER_70:
+             r8168_mac_ocp_write(tp, 0xcdd0, 0x9003);
+             r8168_mac_ocp_modify(tp, 0xe034, 0x0000, 0xc000);
+             r8168_mac_ocp_modify(tp, 0xe0a2, 0x0000, BIT(0));
+             r8168_mac_ocp_write(tp, 0xcdd2, 0x8c09);
+             r8168_mac_ocp_write(tp, 0xcdd8, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdd4, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdda, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdd6, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcddc, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcde8, 0x887a);
+             r8168_mac_ocp_write(tp, 0xcdea, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdec, 0x8c09);
+             r8168_mac_ocp_write(tp, 0xcdee, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdf0, 0x8a62);
+             r8168_mac_ocp_write(tp, 0xcdf2, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdf4, 0x883e);
+             r8168_mac_ocp_write(tp, 0xcdf6, 0x9003);
+             r8168_mac_ocp_modify(tp, 0xe032, 0x0000, BIT(14));
+             break;
+     case RTL_GIGA_MAC_VER_61 ... RTL_GIGA_MAC_VER_66:
+             r8168_mac_ocp_write(tp, 0xcdd0, 0x9003);
+             r8168_mac_ocp_modify(tp, 0xe034, 0x0000, 0xc000);
+             r8168_mac_ocp_modify(tp, 0xe0a2, 0x0000, BIT(0));
+             r8168_mac_ocp_write(tp, 0xcdd2, 0x889c);
+             r8168_mac_ocp_write(tp, 0xcdd8, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdd4, 0x8c30);
+             r8168_mac_ocp_write(tp, 0xcdda, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdd6, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcddc, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcde8, 0x883e);
+             r8168_mac_ocp_write(tp, 0xcdea, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdec, 0x889c);
+             r8168_mac_ocp_write(tp, 0xcdee, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdf0, 0x8C09);
+             r8168_mac_ocp_write(tp, 0xcdf2, 0x9003);
+             r8168_mac_ocp_modify(tp, 0xe032, 0x0000, BIT(14));
+             break;
+     case RTL_GIGA_MAC_VER_46 ... RTL_GIGA_MAC_VER_52:
+             r8168_mac_ocp_modify(tp, 0xe034, 0x0000, 0xc000);
+             r8168_mac_ocp_modify(tp, 0xe0a2, 0x0000, BIT(0));
+             r8168_mac_ocp_write(tp, 0xe02c, 0x1880);
+             r8168_mac_ocp_write(tp, 0xe02e, 0x4880);
+             r8168_mac_ocp_write(tp, 0xcdd8, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdda, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcddc, 0x9003);
+             r8168_mac_ocp_write(tp, 0xcdd2, 0x883c);
+             r8168_mac_ocp_write(tp, 0xcdd4, 0x8c12);
+             r8168_mac_ocp_write(tp, 0xcdd6, 0x9003);
+             RTL_W8(tp, 0xb6, RTL_R8(tp, 0xb6) | BIT(0));
+             break;
+     default:
+             return;
+     }
+     /* chip can trigger LTR */
+     r8168_mac_ocp_modify(tp, 0xe032, 0x0003, BIT(0)); }
+
+static void rtl_disable_ltr(struct rtl8169_private *tp) {
+     switch (tp->mac_version) {
+     case RTL_GIGA_MAC_VER_46 ... RTL_GIGA_MAC_VER_80:
+             r8168_mac_ocp_modify(tp, 0xe032, 0x0003, 0);
+             break;
+     default:
+             break;
+     }
+}
+
 static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, 

bool enable)  {
      u8 val8;

@@ -2947,6 +3042,7 @@ static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
                      break;
              }

+             rtl_enable_ltr(tp);
              switch (tp->mac_version) {
              case RTL_GIGA_MAC_VER_46 ... RTL_GIGA_MAC_VER_48:
              case RTL_GIGA_MAC_VER_61 ... RTL_GIGA_MAC_VER_LAST:

@@ -2968,6 +3064,7 @@ static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
                      break;
              }

+             rtl_disable_ltr(tp);
              switch (tp->mac_version) {
              case RTL_GIGA_MAC_VER_70:
              case RTL_GIGA_MAC_VER_80:

@@ -4811,6 +4908,7 @@ static void rtl8169_down(struct rtl8169_private 

*tp)

      rtl8169_cleanup(tp);
      rtl_disable_exit_l1(tp);
+     rtl_disable_ltr(tp);
      rtl_prepare_power_down(tp);

      if (tp->dash_type != RTL_DASH_NONE && !tp->saved_wolopts)