--- a/libraries/Ethernet/src/ETH.h
+++ b/libraries/Ethernet/src/ETH.h
@@ -119,6 +119,10 @@
 #endif
 #ifndef ETH_RMII_CLK
 #define ETH_RMII_CLK 50
+#endif
+// Input for an RMII clock generated by the EMAC (EMAC_CLK_OUT) and looped back externally, -1 if unused
+#ifndef ETH_RMII_CLK_IN
+#define ETH_RMII_CLK_IN -1
 #endif
 #endif
 #endif /* CONFIG_ETH_USE_ESP32_EMAC */
--- a/libraries/Ethernet/src/ETH.cpp
+++ b/libraries/Ethernet/src/ETH.cpp
@@ -223,7 +223,7 @@
     .clock_config_out_in = {                                                       \
       .rmii = {                                                                    \
         .clock_mode = EMAC_CLK_EXT_IN,                                             \
-        .clock_gpio = (emac_rmii_clock_gpio_t) - 1                                 \
+        .clock_gpio = (emac_rmii_clock_gpio_t)ETH_RMII_CLK_IN                      \
       }                                                                            \
     },                                                                             \
   }
@@ -277,8 +277,13 @@
   _pin_power = digitalPinToGPIONumber(power);
 
   if (!perimanClearPinBus(_pin_rmii_clock)) {
+    return false;
+  }
+#if CONFIG_IDF_TARGET_ESP32P4 && ETH_RMII_CLK_IN >= 0
+  if (!perimanClearPinBus(ETH_RMII_CLK_IN)) {
     return false;
   }
+#endif
   if (!perimanClearPinBus(_pin_mdc)) {
     return false;
   }
@@ -429,8 +434,13 @@
   _eth_started = true;
 
   if (!perimanSetPinBus(_pin_rmii_clock, ESP32_BUS_TYPE_ETHERNET_CLK, (void *)(this), -1, -1)) {
+    goto err;
+  }
+#if CONFIG_IDF_TARGET_ESP32P4 && ETH_RMII_CLK_IN >= 0
+  if (!perimanSetPinBus(ETH_RMII_CLK_IN, ESP32_BUS_TYPE_ETHERNET_CLK, (void *)(this), -1, -1)) {
     goto err;
   }
+#endif
   if (!perimanSetPinBus(_pin_mdc, ESP32_BUS_TYPE_ETHERNET_MDC, (void *)(this), -1, -1)) {
     goto err;
   }