diff --git a/drivers/net/ethernet/nvidia/nvethernet/selftests.c b/drivers/net/ethernet/nvidia/nvethernet/selftests.c
index 04ce4858..e69c26a7 100644
--- a/drivers/net/ethernet/nvidia/nvethernet/selftests.c
+++ b/drivers/net/ethernet/nvidia/nvethernet/selftests.c
@@ -1,5 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
-/* Copyright (c) 2019-2022, NVIDIA CORPORATION & AFFILIATES. All rights reserved */
+// SPDX-FileCopyrightText: Copyright (c) 2019-2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved
 
 #ifndef OSI_STRIPPED_LIB
 #include "ether_linux.h"
@@ -290,7 +290,11 @@ static int ether_test_phy_loopback(struct ether_priv_data *pdata)
 	if (!pdata->phydev)
 		return -ENODEV;
 
+#if defined(NV_PHY_LOOPBACK_HAS_SPEED_ARG) /* Linux v6.15 */
+	ret = phy_loopback(pdata->phydev, true, 0);
+#else
 	ret = phy_loopback(pdata->phydev, true);
+#endif
 	if (ret != 0 && ret != -EBUSY)
 		return ret;
 
@@ -406,7 +410,11 @@ void ether_selftest_run(struct net_device *dev,
 		case ETHER_LOOPBACK_PHY:
 			ret = -EOPNOTSUPP;
 			if (dev->phydev)
+#if defined(NV_PHY_LOOPBACK_HAS_SPEED_ARG) /* Linux v6.15 */
+				ret = phy_loopback(dev->phydev, true, 0);
+#else
 				ret = phy_loopback(dev->phydev, true);
+#endif
 			if (!ret)
 				break;
 		/* Fallthrough */
@@ -439,7 +447,11 @@ void ether_selftest_run(struct net_device *dev,
 		case ETHER_LOOPBACK_PHY:
 			ret = -EOPNOTSUPP;
 			if (dev->phydev)
+#if defined(NV_PHY_LOOPBACK_HAS_SPEED_ARG) /* Linux v6.15 */
+				ret = phy_loopback(dev->phydev, false, 0);
+#else
 				ret = phy_loopback(dev->phydev, false);
+#endif
 			if (!ret)
 				break;
 		/* Fallthrough */
diff --git a/scripts/conftest/Makefile b/scripts/conftest/Makefile
index 335fa16b..be689ced 100644
--- a/scripts/conftest/Makefile
+++ b/scripts/conftest/Makefile
@@ -173,6 +173,7 @@ NV_CONFTEST_FUNCTION_COMPILE_TESTS += pci_epc_event_ops_struct_has_core_deinit
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += pci_epc_event_ops_struct_has_epc_deinit
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += pci_epc_event_ops_struct_has_epc_init
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += pci_epc_irq_type_enum_present
+NV_CONFTEST_FUNCTION_COMPILE_TESTS += phy_loopback_has_speed_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += platform_driver_struct_remove_returns_void
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += register_shrinker_has_fmt_arg
 NV_CONFTEST_FUNCTION_COMPILE_TESTS += shrinker_alloc
diff --git a/scripts/conftest/conftest.sh b/scripts/conftest/conftest.sh
index 18b4b251..d094f203 100755
--- a/scripts/conftest/conftest.sh
+++ b/scripts/conftest/conftest.sh
@@ -7903,6 +7903,23 @@ compile_test() {
             compile_check_conftest "$CODE" "NV_PCI_EPC_EVENT_OPS_STRUCT_HAS_EPC_INIT" "" "types"
         ;;
 
+        phy_loopback_has_speed_arg)
+            #
+            # Determine if phy_loopback() has 'speed' argument.
+            #
+            # Commit 0d60fd50328a ("net: phy: Support speed selection for PHY
+            # loopback") add a 'speed' argument to phy_loopback() in Linux
+            # v6.15.
+            #
+            CODE="
+            #include <linux/phy.h>
+            int conftest_phy_loopback_has_speed_arg(struct phy_device *phydev) {
+                return phy_loopback(phydev, true, 0);
+            }"
+
+            compile_check_conftest "$CODE" "NV_PHY_LOOPBACK_HAS_SPEED_ARG" "" "types"
+        ;;
+
         platform_driver_struct_remove_returns_void)
             #
             # Determine if the 'platform_driver' structure 'remove' function