[ili9xxx] Keep the custom init sequence in a shared PROGMEM table

The table carries the 0 terminator init_lcd_() stops at; the vector it
replaces had none, so the loop read past its end.

esphome/components/ili9xxx/display.py

@@ -234,7 +234,10 @@ async def to_code(config: ConfigType) -> None:
         sequence = []
         for seq in init_sequences:
             sequence.extend(seq)
-        cg.add(var.add_init_sequence(sequence))
+        # init_lcd_() stops at a 0 command
+        sequence.append(0)
+        table = cg.shared_progmem_array("ili9xxx_init_sequence", cg.uint8, sequence)
+        cg.add(var.add_init_sequence(table))
 
     if pixel_mode := config.get(CONF_PIXEL_MODE):
         cg.add(var.set_pixel_mode(pixel_mode))

esphome/components/ili9xxx/ili9xxx_display.cpp

@@ -32,7 +32,7 @@ void ILI9XXXDisplay::set_madctl() {
 void ILI9XXXDisplay::setup() {
   this->setup_pins_();
   this->init_lcd_(this->init_sequence_);
-  this->init_lcd_(this->extra_init_sequence_.data());
+  this->init_lcd_(this->extra_init_sequence_);
   switch (this->pixel_mode_) {
     case PIXEL_MODE_16:
       if (this->is_18bitdisplay_) {

esphome/components/ili9xxx/ili9xxx_display.h

@@ -58,7 +58,7 @@ class ILI9XXXDisplay : public display::DisplayBuffer,
     }
   }
 
-  void add_init_sequence(const std::vector<uint8_t> &sequence) { this->extra_init_sequence_ = sequence; }
+  void add_init_sequence(const uint8_t *sequence) { this->extra_init_sequence_ = sequence; }
   void set_dc_pin(GPIOPin *dc_pin) { dc_pin_ = dc_pin; }
   float get_setup_priority() const override;
   void set_reset_pin(GPIOPin *reset) { this->reset_pin_ = reset; }
@@ -114,7 +114,8 @@ class ILI9XXXDisplay : public display::DisplayBuffer,
   void reset_();
 
   uint8_t const *init_sequence_{};
-  std::vector<uint8_t> extra_init_sequence_;
+  // Shared PROGMEM table ending in a 0 command, like the built-in sequences
+  const uint8_t *extra_init_sequence_{nullptr};
   int16_t width_{0};   ///< Display width as modified by current rotation
   int16_t height_{0};  ///< Display height as modified by current rotation
   int16_t offset_x_{0};

tests/component_tests/ili9xxx/config/init_sequence.yaml

@@ -0,0 +1,31 @@
+esphome:
+  name: test
+
+esp32:
+  board: esp32dev
+  framework:
+    type: arduino
+
+spi:
+  clk_pin: GPIO18
+  mosi_pin: GPIO23
+
+display:
+  - platform: ili9xxx
+    id: first
+    model: ST7789V
+    cs_pin: GPIO5
+    dc_pin: GPIO17
+    invert_colors: false
+    init_sequence:
+      - [0x36, 0x48]
+      - [0x3A, 0x55]
+  - platform: ili9xxx
+    id: second
+    model: ST7789V
+    cs_pin: GPIO4
+    dc_pin: GPIO16
+    invert_colors: false
+    init_sequence:
+      - [0x36, 0x48]
+      - [0x3A, 0x55]

tests/component_tests/ili9xxx/test_ili9xxx.py

@@ -4,6 +4,7 @@ from __future__ import annotations
 
 from collections.abc import Callable
 from pathlib import Path
+import re
 
 
 def test_ili9xxx_placement_new_uses_model_subclass(
@@ -29,3 +30,19 @@ def test_ili9xxx_placement_new_uses_model_subclass(
     assert "new(tft_display) ili9xxx::ILI9XXXST7789V()" in main_cpp
     # Base-class default constructor must NOT be used.
     assert "new(tft_display) ili9xxx::ILI9XXXDisplay()" not in main_cpp
+
+
+def test_extra_init_sequence_is_terminated_progmem_table(
+    generate_main: Callable[[str | Path], str],
+    component_config_path: Callable[[str], Path],
+) -> None:
+    """A custom init sequence is a 0 terminated PROGMEM table shared by equal displays."""
+    main_cpp = generate_main(component_config_path("init_sequence.yaml"))
+
+    tables = re.findall(r"(\w+)->add_init_sequence\((\w+)\);", main_cpp)
+    assert {t[0] for t in tables} == {"first", "second"}
+    assert len({t[1] for t in tables}) == 1
+    assert (
+        f"static constexpr uint8_t {tables[0][1]}[] PROGMEM = {{54, 1, 72, 58, 1, 85, 0}};"
+        in main_cpp
+    )