[esphome][ota] Disable loop while idle, wake on listening-socket activity (#15636)

esphome/components/esphome/ota/__init__.py

@@ -78,6 +78,14 @@ def ota_esphome_final_validate(config):
         else:
             new_ota_conf.append(ota_conf)
 
+    if len(merged_ota_esphome_configs_by_port) > 1:
+        raise cv.Invalid(
+            f"Only a single port is supported for '{CONF_OTA}' "
+            f"'{CONF_PLATFORM}: {CONF_ESPHOME}'. Got ports "
+            f"{sorted(merged_ota_esphome_configs_by_port.keys())}. Consolidate "
+            f"onto a single port; configs sharing a port are merged automatically."
+        )
+
     new_ota_conf.extend(merged_ota_esphome_configs_by_port.values())
 
     full_conf[CONF_OTA] = new_ota_conf
@@ -147,6 +155,8 @@ async def to_code(config: ConfigType) -> None:
         cg.add(var.set_auth_password(config[CONF_PASSWORD]))
         cg.add_define("USE_OTA_PASSWORD")
     cg.add_define("USE_OTA_VERSION", config[CONF_VERSION])
+    # Build flag so lwip_fast_select.c (a .c file that can't include defines.h) sees it.
+    cg.add_build_flag("-DUSE_OTA_PLATFORM_ESPHOME")
 
     await cg.register_component(var, config)
     await ota_to_code(var, config)

esphome/components/esphome/ota/ota_esphome.cpp

@@ -15,6 +15,9 @@
 #include "esphome/core/helpers.h"
 #include "esphome/core/log.h"
 #include "esphome/core/util.h"
+#ifdef USE_LWIP_FAST_SELECT
+#include "esphome/core/lwip_fast_select.h"
+#endif
 
 #include <cerrno>
 #include <cstdio>
@@ -28,6 +31,17 @@ static constexpr size_t OTA_BUFFER_SIZE = 1024;                  // buffer size
 static constexpr uint32_t OTA_SOCKET_TIMEOUT_HANDSHAKE = 20000;  // milliseconds for initial handshake
 static constexpr uint32_t OTA_SOCKET_TIMEOUT_DATA = 90000;       // milliseconds for data transfer
 
+// Single-instance pointer — multi-port configs are rejected in final_validate.
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables)
+static ESPHomeOTAComponent *global_esphome_ota_component = nullptr;
+
+// Called from any context (LwIP TCP/IP task, RP2040 user-IRQ).
+extern "C" void esphome_wake_ota_component_any_context() {
+  if (global_esphome_ota_component != nullptr) {
+    global_esphome_ota_component->enable_loop_soon_any_context();
+  }
+}
+
 void ESPHomeOTAComponent::setup() {
   this->server_ = socket::socket_ip_loop_monitored(SOCK_STREAM, 0).release();  // monitored for incoming connections
   if (this->server_ == nullptr) {
@@ -65,6 +79,14 @@ void ESPHomeOTAComponent::setup() {
     this->server_failed_(LOG_STR("listen"));
     return;
   }
+
+  // loop() self-disables on its first idle tick; no explicit disable_loop() needed here.
+  global_esphome_ota_component = this;
+#ifdef USE_LWIP_FAST_SELECT
+  // Filter fast-select wakes to this listener only. If the sock lookup returns nullptr,
+  // no wakes fire and loop() falls back to the self-disable safety net.
+  esphome_fast_select_set_ota_listener_sock(esphome_lwip_get_sock(this->server_->get_fd()));
+#endif
 }
 
 void ESPHomeOTAComponent::dump_config() {
@@ -81,13 +103,15 @@ void ESPHomeOTAComponent::dump_config() {
 }
 
 void ESPHomeOTAComponent::loop() {
-  // Skip handle_handshake_() call if no client connected and no incoming connections
-  // This optimization reduces idle loop overhead when OTA is not active
-  // Note: No need to check server_ for null as the component is marked failed in setup()
-  // if server_ creation fails
-  if (this->client_ != nullptr || this->server_->ready()) {
-    this->handle_handshake_();
+  // Self-disabling idle loop. Runs when a wake path marks us pending-enable (fast-select
+  // listener filter, raw-TCP accept_fn_, or host select), finds no work, and goes back
+  // to sleep. cleanup_connection_() deliberately leaves the loop enabled for one more
+  // iteration so a connection queued mid-session is still caught here.
+  if (this->client_ == nullptr && !this->server_->ready()) {
+    this->disable_loop();
+    return;
   }
+  this->handle_handshake_();
 }
 
 static const uint8_t FEATURE_SUPPORTS_COMPRESSION = 0x01;
@@ -566,6 +590,9 @@ void ESPHomeOTAComponent::cleanup_connection_() {
 #ifdef USE_OTA_PASSWORD
   this->cleanup_auth_();
 #endif
+  // Intentionally no disable_loop() — letting loop() run one more iteration catches
+  // any connection that queued on the listener mid-session (otherwise the wake flag,
+  // set while we were in LOOP state, would be lost to enable_pending_loops_()).
 }
 
 void ESPHomeOTAComponent::yield_and_feed_watchdog_() {

esphome/components/socket/lwip_raw_tcp_impl.cpp

@@ -11,6 +11,10 @@
 #include "esphome/core/wake.h"
 #include "esphome/core/log.h"
 
+#ifdef USE_OTA_PLATFORM_ESPHOME
+extern "C" void esphome_wake_ota_component_any_context();
+#endif
+
 #ifdef USE_ESP8266
 #include <coredecls.h>  // For esp_schedule()
 #elif defined(USE_RP2040)
@@ -854,6 +858,10 @@ err_t LWIPRawListenImpl::accept_fn_(struct tcp_pcb *newpcb, err_t err) {
   tcp_err(newpcb, LWIPRawListenImpl::s_queued_err_fn);
   tcp_recv(newpcb, LWIPRawListenImpl::s_queued_recv_fn);
   LWIP_LOG("Accepted connection, queue size: %d", this->accepted_socket_count_);
+#ifdef USE_OTA_PLATFORM_ESPHOME
+  // Must run before wake_loop_any_context() so flags are visible when the main task wakes.
+  esphome_wake_ota_component_any_context();
+#endif
   // Wake the main loop immediately so it can accept the new connection.
   esphome::wake_loop_any_context();
   return ERR_OK;

esphome/core/lwip_fast_select.c

@@ -157,6 +157,17 @@ _Static_assert(offsetof(struct lwip_sock, rcvevent) == ESPHOME_LWIP_SOCK_RCVEVEN
 // Saved original event_callback pointer — written once in first hook_socket(), read from TCP/IP task.
 static netconn_callback s_original_callback = NULL;
 
+#ifdef USE_OTA_PLATFORM_ESPHOME
+static struct netconn *s_ota_listener_conn = NULL;
+extern void esphome_wake_ota_component_any_context(void);
+
+void esphome_fast_select_set_ota_listener_sock(struct lwip_sock *sock) {
+  s_ota_listener_conn = (sock != NULL) ? sock->conn : NULL;
+}
+#else
+void esphome_fast_select_set_ota_listener_sock(struct lwip_sock *sock) { (void) sock; }
+#endif
+
 // Wrapper callback: calls original event_callback + notifies main loop task.
 // Called from LwIP's TCP/IP thread when socket events occur (task context, not ISR).
 static void esphome_socket_event_callback(struct netconn *conn, enum netconn_evt evt, u16_t len) {
@@ -171,6 +182,13 @@ static void esphome_socket_event_callback(struct netconn *conn, enum netconn_evt
   // (rcvevent++ with a NULL pbuf or error in recvmbox), so error conditions
   // already wake the main loop through the RCVPLUS path.
   if (evt == NETCONN_EVT_RCVPLUS) {
+#ifdef USE_OTA_PLATFORM_ESPHOME
+    // Mark OTA pending-enable only for events on its listen socket. MUST happen
+    // before xTaskNotifyGive so the flags are visible when the main task wakes.
+    if (conn == s_ota_listener_conn) {
+      esphome_wake_ota_component_any_context();
+    }
+#endif
     TaskHandle_t task = esphome_main_task_handle;
     if (task != NULL) {
       xTaskNotifyGive(task);

esphome/core/lwip_fast_select.h

@@ -53,6 +53,12 @@ static inline bool esphome_lwip_socket_has_data(struct lwip_sock *sock) {
 /// The sock pointer must have been obtained from esphome_lwip_get_sock().
 void esphome_lwip_hook_socket(struct lwip_sock *sock);
 
+/// Set the listener netconn that the fast-select callback filters OTA wakes against.
+/// After this is called, the OTA wake hook only fires for RCVPLUS events whose `conn`
+/// matches this listener. Passing NULL disables OTA wakes (no event matches a NULL
+/// listener) — correct behavior before install and after teardown.
+void esphome_fast_select_set_ota_listener_sock(struct lwip_sock *sock);
+
 /// Set or clear TCP_NODELAY on a socket's tcp_pcb directly.
 /// Must be called with the TCPIP core lock held (LwIPLock in C++).
 /// This bypasses lwip_setsockopt() overhead (socket lookups, switch cascade,

tests/component_tests/ota/test_esphome_ota.py

@@ -0,0 +1,105 @@
+"""Tests for the esphome OTA platform final_validate logic."""
+
+from __future__ import annotations
+
+import logging
+from typing import Any
+
+import pytest
+
+from esphome import config_validation as cv
+from esphome.components.esphome.ota import ota_esphome_final_validate
+from esphome.const import (
+    CONF_ESPHOME,
+    CONF_ID,
+    CONF_OTA,
+    CONF_PASSWORD,
+    CONF_PLATFORM,
+    CONF_PORT,
+    CONF_VERSION,
+)
+from esphome.core import ID
+import esphome.final_validate as fv
+
+
+def _make_ota_config(port: int = 3232, **kwargs: Any) -> dict[str, Any]:
+    config: dict[str, Any] = {
+        CONF_PLATFORM: CONF_ESPHOME,
+        CONF_ID: ID(f"ota_esphome_{port}", is_manual=False),
+        CONF_VERSION: 2,
+        CONF_PORT: port,
+    }
+    config.update(kwargs)
+    return config
+
+
+def test_single_esphome_ota_instance_accepted() -> None:
+    """A single ESPHome OTA config passes final_validate untouched."""
+    full_conf = {CONF_OTA: [_make_ota_config(port=3232)]}
+    token = fv.full_config.set(full_conf)
+    try:
+        ota_esphome_final_validate({})
+        updated = fv.full_config.get()
+        assert len(updated[CONF_OTA]) == 1
+        assert updated[CONF_OTA][0][CONF_PORT] == 3232
+    finally:
+        fv.full_config.reset(token)
+
+
+def test_same_port_configs_merge(caplog: pytest.LogCaptureFixture) -> None:
+    """Two ESPHome OTA configs on the same port merge into one instance."""
+    full_conf = {
+        CONF_OTA: [
+            _make_ota_config(port=3232, **{CONF_PASSWORD: "pw"}),
+            _make_ota_config(port=3232),
+        ]
+    }
+    token = fv.full_config.set(full_conf)
+    try:
+        with caplog.at_level(logging.WARNING):
+            ota_esphome_final_validate({})
+        updated = fv.full_config.get()
+        assert len(updated[CONF_OTA]) == 1
+        assert updated[CONF_OTA][0][CONF_PORT] == 3232
+        assert any("Found and merged" in record.message for record in caplog.records), (
+            "Expected merge warning not found in log"
+        )
+    finally:
+        fv.full_config.reset(token)
+
+
+def test_multiple_ports_rejected() -> None:
+    """Two ESPHome OTA configs on different ports raise cv.Invalid."""
+    full_conf = {
+        CONF_OTA: [
+            _make_ota_config(port=3232),
+            _make_ota_config(port=3233),
+        ]
+    }
+    token = fv.full_config.set(full_conf)
+    try:
+        with pytest.raises(
+            cv.Invalid,
+            match=r"Only a single port is supported for 'ota' 'platform: esphome'",
+        ):
+            ota_esphome_final_validate({})
+    finally:
+        fv.full_config.reset(token)
+
+
+def test_non_esphome_ota_unaffected() -> None:
+    """Non-esphome OTA platforms are not subject to the single-instance rule."""
+    full_conf = {
+        CONF_OTA: [
+            _make_ota_config(port=3232),
+            {CONF_PLATFORM: "web_server", CONF_ID: ID("ota_ws", is_manual=False)},
+            {CONF_PLATFORM: "http_request", CONF_ID: ID("ota_hr", is_manual=False)},
+        ]
+    }
+    token = fv.full_config.set(full_conf)
+    try:
+        ota_esphome_final_validate({})
+        updated = fv.full_config.get()
+        assert len(updated[CONF_OTA]) == 3
+    finally:
+        fv.full_config.reset(token)