[it8951] Hold display enable pins off during deep-sleep (#20471)

esphome/components/it8951/display.py

@@ -145,8 +145,8 @@ IT8951Model(
     reset_pin=12,
     cs_pin=10,
     # Board power-enable rails: 1.8V logic supply (GPIO21) and the EPD supply
-    # (GPIO11). Driven high during setup so no separate power_supply is needed.
-    enable_pin=[21, 11],
+    # (GPIO11). Driven high during setup so no separate power_supply is needed, and held low during deep_sleep.
+    enable_pin=[{"number": 21, "hold_state": True}, {"number": 11, "hold_state": True}],
     vcom=1400,
     # reTerminal E1003 panel firmware only accepts the 0x0002 VCOM SET
     # selector; using the default 0x0001 leaves VCOM unchanged and breaks

esphome/components/it8951/it8951.cpp

@@ -351,6 +351,12 @@ void IT8951Display::on_safe_shutdown() {
   this->spi_cmd_(TCON_SLEEP);
 }
 
+void IT8951Display::on_powerdown() {
+  for (auto *pin : this->enable_pins_) {
+    pin->digital_write(false);
+  }
+}
+
 // --- Init op enqueuers -------------------------------------------------------
 
 void IT8951Display::enqueue_init_reset_() {

esphome/components/it8951/it8951.h

@@ -150,6 +150,7 @@ class IT8951Display : public Display,
   void loop() override;
   void dump_config() override;
   void on_safe_shutdown() override;
+  void on_powerdown() override;
   float get_setup_priority() const override { return setup_priority::PROCESSOR; }
 
   // --- Config setters (called from generated code) ---