[st7701s] Keep the init sequence in a shared PROGMEM table

esphome/components/st7701s/display.py

@@ -181,7 +181,8 @@ async def to_code(config: ConfigType) -> None:
     sequence = []
     for seq in config[CONF_INIT_SEQUENCE]:
         sequence.extend(seq)
-    cg.add(var.set_init_sequence(sequence))
+    table = cg.shared_progmem_array("st7701s_init_sequence", cg.uint8, sequence)
+    cg.add(var.set_init_sequence(table, len(sequence)))
     cg.add(var.set_color_mode(COLOR_ORDERS[config[CONF_COLOR_ORDER]]))
     cg.add(var.set_invert_colors(config[CONF_INVERT_COLORS]))
     cg.add(var.set_hsync_pulse_width(config[CONF_HSYNC_PULSE_WIDTH]))

esphome/components/st7701s/st7701s.cpp

@@ -144,14 +144,14 @@ void ST7701S::write_sequence_(uint8_t cmd, size_t len, const uint8_t *bytes) {
 }
 
 void ST7701S::write_init_sequence_() {
-  for (size_t i = 0; i != this->init_sequence_.size();) {
+  for (size_t i = 0; i != this->init_sequence_len_;) {
     uint8_t cmd = this->init_sequence_[i++];
     size_t len = this->init_sequence_[i++];
     if (len == ST7701S_DELAY_FLAG) {
       ESP_LOGV(TAG, "Delay %dms", cmd);
       delay(cmd);
     } else {
-      this->write_sequence_(cmd, len, &this->init_sequence_[i]);
+      this->write_sequence_(cmd, len, this->init_sequence_ + i);
       i += len;
       ESP_LOGV(TAG, "Command %X, %d bytes", cmd, len);
       if (cmd == SW_RESET_CMD)

esphome/components/st7701s/st7701s.h

@@ -62,7 +62,10 @@ class ST7701S final : public display::Display,
   void set_vsync_pulse_width(uint16_t vsync_pulse_width) { this->vsync_pulse_width_ = vsync_pulse_width; }
   void set_vsync_back_porch(uint16_t vsync_back_porch) { this->vsync_back_porch_ = vsync_back_porch; }
   void set_vsync_front_porch(uint16_t vsync_front_porch) { this->vsync_front_porch_ = vsync_front_porch; }
-  void set_init_sequence(const std::vector<uint8_t> &init_sequence) { this->init_sequence_ = init_sequence; }
+  void set_init_sequence(const uint8_t *init_sequence, size_t len) {
+    this->init_sequence_ = init_sequence;
+    this->init_sequence_len_ = len;
+  }
   void set_mirror_x(bool mirror_x) { this->mirror_x_ = mirror_x; }
   void set_mirror_y(bool mirror_y) { this->mirror_y_ = mirror_y; }
   void set_offsets(int16_t offset_x, int16_t offset_y) {
@@ -95,7 +98,9 @@ class ST7701S final : public display::Display,
   uint16_t vsync_pulse_width_ = 10;
   uint16_t vsync_back_porch_ = 10;
   uint16_t vsync_front_porch_ = 10;
-  std::vector<uint8_t> init_sequence_;
+  // Shared PROGMEM table
+  const uint8_t *init_sequence_{nullptr};
+  size_t init_sequence_len_{0};
   uint32_t pclk_frequency_ = 16 * 1000 * 1000;
   bool pclk_inverted_{true};
 

tests/component_tests/st7701s/test_init_sequence.py

@@ -0,0 +1,61 @@
+"""Tests for the st7701s init sequence codegen."""
+
+from collections.abc import Callable
+from pathlib import Path
+import re
+
+_YAML = """
+esphome:
+  name: st7701s-test
+esp32:
+  board: esp32-s3-devkitc-1
+  framework:
+    type: esp-idf
+psram:
+  mode: octal
+spi:
+  clk_pin: 10
+  mosi_pin: 11
+display:
+{displays}
+"""
+
+_DISPLAY = """
+  - platform: st7701s
+    id: {display_id}
+    dimensions:
+      width: 480
+      height: 480
+    cs_pin: {cs_pin}
+    de_pin: 18
+    hsync_pin: 16
+    vsync_pin: 17
+    pclk_pin: 21
+    init_sequence:
+      - 1
+      - [0x23, 0xA, 0xB]
+      - delay 20ms
+    data_pins: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 13, 14, 15, 38, 39]
+"""
+
+
+def test_init_sequence_is_progmem_table(
+    generate_main: Callable[[str | Path], str],
+    tmp_path: Path,
+) -> None:
+    """The init sequence is a PROGMEM table instead of a vector copied at boot."""
+    yaml_file = tmp_path / "st7701s.yaml"
+    yaml_file.write_text(
+        _YAML.format(displays=_DISPLAY.format(display_id="panel", cs_pin=44))
+    )
+
+    main_cpp = generate_main(yaml_file)
+
+    call = re.search(r"panel->set_init_sequence\((\w+), (\d+)\);", main_cpp)
+    assert call is not None
+    table = re.search(
+        rf"static constexpr uint8_t {call.group(1)}\[\] PROGMEM = \{{([^;]*)\}};",
+        main_cpp,
+    )
+    assert table is not None
+    assert len(table.group(1).split(",")) == int(call.group(2))