Workaround brightness transition delay from off in older yeelight models (#58774)

homeassistant/components/yeelight/__init__.py

@@ -35,6 +35,20 @@ _LOGGER = logging.getLogger(__name__)
 STATE_CHANGE_TIME = 0.40  # seconds
 POWER_STATE_CHANGE_TIME = 1  # seconds
 
+#
+# These models do not transition correctly when turning on, and
+# yeelight is no longer updating the firmware on older devices
+#
+# https://github.com/home-assistant/core/issues/58315
+#
+# The problem can be worked around by always setting the brightness
+# even when the bulb is reporting the brightness is already at the
+# desired level.
+#
+MODELS_WITH_DELAYED_ON_TRANSITION = {
+    "color",  # YLDP02YL
+}
+
 DOMAIN = "yeelight"
 DATA_YEELIGHT = DOMAIN
 DATA_UPDATED = "yeelight_{}_data_updated"

homeassistant/components/yeelight/light.py

@@ -63,6 +63,7 @@ from . import (
     DATA_DEVICE,
     DATA_UPDATED,
     DOMAIN,
+    MODELS_WITH_DELAYED_ON_TRANSITION,
     POWER_STATE_CHANGE_TIME,
     YEELIGHT_FLOW_TRANSITION_SCHEMA,
     YeelightEntity,
@@ -614,7 +615,10 @@ class YeelightGenericLight(YeelightEntity, LightEntity):
         """Set bulb brightness."""
         if not brightness:
             return
-        if math.floor(self.brightness) == math.floor(brightness):
+        if (
+            math.floor(self.brightness) == math.floor(brightness)
+            and self._bulb.model not in MODELS_WITH_DELAYED_ON_TRANSITION
+        ):
             _LOGGER.debug("brightness already set to: %s", brightness)
             # Already set, and since we get pushed updates
             # we avoid setting it again to ensure we do not

tests/components/yeelight/test_light.py

@@ -641,6 +641,25 @@ async def test_state_already_set_avoid_ratelimit(hass: HomeAssistant):
     mocked_bulb.async_set_rgb.reset_mock()
     mocked_bulb.last_properties["flowing"] = "0"
 
+    mocked_bulb.model = "color"  # color model needs a workaround (see MODELS_WITH_DELAYED_ON_TRANSITION)
+    await hass.services.async_call(
+        "light",
+        SERVICE_TURN_ON,
+        {
+            ATTR_ENTITY_ID: ENTITY_LIGHT,
+            ATTR_BRIGHTNESS_PCT: PROPERTIES["bright"],
+        },
+        blocking=True,
+    )
+    assert mocked_bulb.async_set_hsv.mock_calls == []
+    assert mocked_bulb.async_set_rgb.mock_calls == []
+    assert mocked_bulb.async_set_color_temp.mock_calls == []
+    assert mocked_bulb.async_set_brightness.mock_calls == [
+        call(pytest.approx(50.1, 0.1), duration=350, light_type=ANY)
+    ]
+    mocked_bulb.async_set_brightness.reset_mock()
+
+    mocked_bulb.model = "colora"  # colora does not need a workaround
     await hass.services.async_call(
         "light",
         SERVICE_TURN_ON,
@@ -683,6 +702,7 @@ async def test_state_already_set_avoid_ratelimit(hass: HomeAssistant):
     assert mocked_bulb.async_set_brightness.mock_calls == []
 
     mocked_bulb.last_properties["flowing"] = "1"
+
     await hass.services.async_call(
         "light",
         SERVICE_TURN_ON,