[PATCH net-next 2/2] r8169: disable RTL8126 ZRX-DC timeout

[ChunHao Lin <hau@realtek.com>]

Disable it due to it dose not meet ZRX-DC specification. If it is enabled,
device will exit L1 substate every 100ms. Disable it for saving more power
in L1 substate.

Signed-off-by: ChunHao Lin <hau@realtek.com>
---
 drivers/net/ethernet/realtek/r8169_main.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 3c663fca07d3..dfc96b09b85e 100644
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -2852,6 +2852,21 @@ static u32 rtl_csi_read(struct rtl8169_private *tp, int addr)
 		RTL_R32(tp, CSIDR) : ~0;
 }
 
+static void rtl_disable_zrxdc_timeout(struct rtl8169_private *tp)
+{
+	struct pci_dev *pdev = tp->pci_dev;
+	u8 val;
+
+	if (pdev->cfg_size > 0x0890 &&
+	    pci_read_config_byte(pdev, 0x0890, &val) == PCIBIOS_SUCCESSFUL &&
+	    pci_write_config_byte(pdev, 0x0890, val & ~BIT(0)) == PCIBIOS_SUCCESSFUL)
+		return;
+
+	netdev_notice_once(tp->dev,
+		"No native access to PCI extended config space, falling back to CSI\n");
+	rtl_csi_write(tp, 0x0890, rtl_csi_read(tp, 0x0890) & ~BIT(0));
+}
+
 static void rtl_set_aspm_entry_latency(struct rtl8169_private *tp, u8 val)
 {
 	struct pci_dev *pdev = tp->pci_dev;
@@ -3824,6 +3839,7 @@ static void rtl_hw_start_8125d(struct rtl8169_private *tp)
 
 static void rtl_hw_start_8126a(struct rtl8169_private *tp)
 {
+	rtl_disable_zrxdc_timeout(tp);
 	rtl_set_def_aspm_entry_latency(tp);
 	rtl_hw_start_8125_common(tp);
 }
-- 
2.43.0