[usb_host] Add wake_loop_threadsafe() for low-latency USB event processing

esphome/components/usb_host/__init__.py

@@ -1,4 +1,5 @@
 import esphome.codegen as cg
+from esphome.components import socket
 from esphome.components.esp32 import (
     VARIANT_ESP32P4,
     VARIANT_ESP32S2,
@@ -11,7 +12,7 @@ from esphome.const import CONF_DEVICES, CONF_ID
 from esphome.cpp_types import Component
 from esphome.types import ConfigType
 
-AUTO_LOAD = ["bytebuffer"]
+AUTO_LOAD = ["bytebuffer", "socket"]
 CODEOWNERS = ["@clydebarrow"]
 DEPENDENCIES = ["esp32"]
 usb_host_ns = cg.esphome_ns.namespace("usb_host")
@@ -71,6 +72,11 @@ async def to_code(config: ConfigType) -> None:
     max_requests = config[CONF_MAX_TRANSFER_REQUESTS]
     cg.add_define("USB_HOST_MAX_REQUESTS", max_requests)
 
+    # USB uses the socket wake_loop_threadsafe() mechanism to wake the main loop from USB task
+    # This enables low-latency (~12μs) USB event processing instead of waiting for
+    # select() timeout (0-16ms). The wake socket is shared across all components.
+    socket.require_wake_loop_threadsafe()
+
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)
     for device in config.get(CONF_DEVICES) or ():

esphome/components/usb_host/usb_host_client.cpp

@@ -3,6 +3,7 @@
 #include "usb_host.h"
 #include "esphome/core/log.h"
 #include "esphome/core/hal.h"
+#include "esphome/core/application.h"
 #include "esphome/components/bytebuffer/bytebuffer.h"
 
 #include <cinttypes>
@@ -174,6 +175,11 @@ static void client_event_cb(const usb_host_client_event_msg_t *event_msg, void *
 
   // Push to lock-free queue (always succeeds since pool size == queue size)
   client->event_queue.push(event);
+
+  // Wake main loop immediately to process USB event instead of waiting for select() timeout
+#if defined(USE_SOCKET_SELECT_SUPPORT) && defined(USE_WAKE_LOOP_THREADSAFE)
+  App.wake_loop_threadsafe();
+#endif
 }
 void USBClient::setup() {
   usb_host_client_config_t config{.is_synchronous = false,