Make mqtt discovery use callback functions (#87883)

homeassistant/components/mqtt/discovery.py

@@ -11,7 +11,7 @@ from typing import Any
 
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import CONF_DEVICE, CONF_PLATFORM
-from homeassistant.core import HomeAssistant
+from homeassistant.core import HomeAssistant, callback
 from homeassistant.data_entry_flow import FlowResultType
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.dispatcher import (
@@ -98,7 +98,8 @@ async def async_start(  # noqa: C901
     mqtt_data = get_mqtt_data(hass)
     mqtt_integrations = {}
 
-    async def async_discovery_message_received(msg: ReceiveMessage) -> None:
+    @callback
+    def async_discovery_message_received(msg: ReceiveMessage) -> None:
         """Process the received message."""
         mqtt_data.last_discovery = time.time()
         payload = msg.payload
@@ -205,11 +206,10 @@ async def async_start(  # noqa: C901
             )
             return
 
-        await async_process_discovery_payload(
-            component, discovery_id, discovery_payload
-        )
+        async_process_discovery_payload(component, discovery_id, discovery_payload)
 
-    async def async_process_discovery_payload(
+    @callback
+    def async_process_discovery_payload(
         component: str, discovery_id: str, payload: MQTTDiscoveryPayload
     ) -> None:
         """Process the payload of a new discovery."""
@@ -228,9 +228,7 @@ async def async_start(  # noqa: C901
                     mqtt_data.discovery_pending_discovered.pop(discovery_hash)
                 else:
                     payload = pending.pop()
-                    await async_process_discovery_payload(
-                        component, discovery_id, payload
-                    )
+                    async_process_discovery_payload(component, discovery_id, payload)
 
             if discovery_hash not in mqtt_data.discovery_pending_discovered:
                 mqtt_data.discovery_pending_discovered[discovery_hash] = {