r8169: disable RTL8126 ZRX-DC timeout

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>
Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://patch.msgid.link/20250318083721.4127-3-hau@realtek.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
index 5c5e256fb9faee6834f453c8186a55d55abd25c5..4eebd9cb40a37031540cb3af539a2902156b33bb 100644 (file)
--- a/drivers/net/ethernet/realtek/r8169_main.c
+++ b/drivers/net/ethernet/realtek/r8169_main.c
@@ -2852,6 +2852,32 @@ 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;
+       u32 csi;
+       int rc;
+       u8 val;
+
+#define RTL_GEN3_RELATED_OFF   0x0890
+#define RTL_GEN3_ZRXDC_NONCOMPL        0x1
+       if (pdev->cfg_size > RTL_GEN3_RELATED_OFF) {
+               rc = pci_read_config_byte(pdev, RTL_GEN3_RELATED_OFF, &val);
+               if (rc == PCIBIOS_SUCCESSFUL) {
+                       val &= ~RTL_GEN3_ZRXDC_NONCOMPL;
+                       rc = pci_write_config_byte(pdev, RTL_GEN3_RELATED_OFF,
+                                                  val);
+                       if (rc == PCIBIOS_SUCCESSFUL)
+                               return;
+               }
+       }
+
+       netdev_notice_once(tp->dev,
+               "No native access to PCI extended config space, falling back to CSI\n");
+       csi = rtl_csi_read(tp, RTL_GEN3_RELATED_OFF);
+       rtl_csi_write(tp, RTL_GEN3_RELATED_OFF, csi & ~RTL_GEN3_ZRXDC_NONCOMPL);
+}
+
 static void rtl_set_aspm_entry_latency(struct rtl8169_private *tp, u8 val)
 {
        struct pci_dev *pdev = tp->pci_dev;
@@ -3824,6 +3850,7 @@ 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);
 }