From d87063865cfa1ebd323dd22a70317cb515fa5fb0 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Mon, 10 Nov 2025 21:57:52 -0600
Subject: [PATCH] [ethernet] Conditionally compile manual_ip to save 24 bytes
 RAM

---
 esphome/components/ethernet/__init__.py            |  1 +
 esphome/components/ethernet/ethernet_component.cpp | 12 ++++++++++--
 esphome/components/ethernet/ethernet_component.h   |  4 ++++
 esphome/core/defines.h                             |  1 +
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/esphome/components/ethernet/__init__.py b/esphome/components/ethernet/__init__.py
index 2f02d227d7..b4d67635c1 100644
--- a/esphome/components/ethernet/__init__.py
+++ b/esphome/components/ethernet/__init__.py
@@ -383,6 +383,7 @@ async def to_code(config):
     cg.add(var.set_use_address(config[CONF_USE_ADDRESS]))
 
     if CONF_MANUAL_IP in config:
+        cg.add_define("USE_ETHERNET_MANUAL_IP")
         cg.add(var.set_manual_ip(manual_ip(config[CONF_MANUAL_IP])))
 
     # Add compile-time define for PHY types with specific code
diff --git a/esphome/components/ethernet/ethernet_component.cpp b/esphome/components/ethernet/ethernet_component.cpp
index 5888ddce60..f3266c851d 100644
--- a/esphome/components/ethernet/ethernet_component.cpp
+++ b/esphome/components/ethernet/ethernet_component.cpp
@@ -550,11 +550,14 @@ void EthernetComponent::start_connect_() {
   }
 
   esp_netif_ip_info_t info;
+#ifdef USE_ETHERNET_MANUAL_IP
   if (this->manual_ip_.has_value()) {
     info.ip = this->manual_ip_->static_ip;
     info.gw = this->manual_ip_->gateway;
     info.netmask = this->manual_ip_->subnet;
-  } else {
+  } else
+#endif
+  {
     info.ip.addr = 0;
     info.gw.addr = 0;
     info.netmask.addr = 0;
@@ -575,6 +578,7 @@ void EthernetComponent::start_connect_() {
   err = esp_netif_set_ip_info(this->eth_netif_, &info);
   ESPHL_ERROR_CHECK(err, "DHCPC set IP info error");
 
+#ifdef USE_ETHERNET_MANUAL_IP
   if (this->manual_ip_.has_value()) {
     LwIPLock lock;
     if (this->manual_ip_->dns1.is_set()) {
@@ -587,7 +591,9 @@ void EthernetComponent::start_connect_() {
       d = this->manual_ip_->dns2;
       dns_setserver(1, &d);
     }
-  } else {
+  } else
+#endif
+  {
     err = esp_netif_dhcpc_start(this->eth_netif_);
     if (err != ESP_ERR_ESP_NETIF_DHCP_ALREADY_STARTED) {
       ESPHL_ERROR_CHECK(err, "DHCPC start error");
@@ -685,7 +691,9 @@ void EthernetComponent::set_clk_mode(emac_rmii_clock_mode_t clk_mode) { this->cl
 void EthernetComponent::add_phy_register(PHYRegister register_value) { this->phy_registers_.push_back(register_value); }
 #endif
 void EthernetComponent::set_type(EthernetType type) { this->type_ = type; }
+#ifdef USE_ETHERNET_MANUAL_IP
 void EthernetComponent::set_manual_ip(const ManualIP &manual_ip) { this->manual_ip_ = manual_ip; }
+#endif
 
 // set_use_address() is guaranteed to be called during component setup by Python code generation,
 // so use_address_ will always be valid when get_use_address() is called - no fallback needed.
diff --git a/esphome/components/ethernet/ethernet_component.h b/esphome/components/ethernet/ethernet_component.h
index f1f0ac9cb8..bffed4dc4a 100644
--- a/esphome/components/ethernet/ethernet_component.h
+++ b/esphome/components/ethernet/ethernet_component.h
@@ -82,7 +82,9 @@ class EthernetComponent : public Component {
   void add_phy_register(PHYRegister register_value);
 #endif
   void set_type(EthernetType type);
+#ifdef USE_ETHERNET_MANUAL_IP
   void set_manual_ip(const ManualIP &manual_ip);
+#endif
   void set_fixed_mac(const std::array<uint8_t, 6> &mac) { this->fixed_mac_ = mac; }
 
   network::IPAddresses get_ip_addresses();
@@ -137,7 +139,9 @@ class EthernetComponent : public Component {
   uint8_t mdc_pin_{23};
   uint8_t mdio_pin_{18};
 #endif
+#ifdef USE_ETHERNET_MANUAL_IP
   optional<ManualIP> manual_ip_{};
+#endif
   uint32_t connect_begin_;
 
   // Group all uint8_t types together (enums and bools)
diff --git a/esphome/core/defines.h b/esphome/core/defines.h
index ac725fbca9..92b5d89cac 100644
--- a/esphome/core/defines.h
+++ b/esphome/core/defines.h
@@ -215,6 +215,7 @@
 #define USE_ARDUINO_VERSION_CODE VERSION_CODE(3, 3, 2)
 #define USE_ETHERNET
 #define USE_ETHERNET_KSZ8081
+#define USE_ETHERNET_MANUAL_IP
 #endif
 
 #ifdef USE_ESP_IDF