[mipi][mipi_spi] SWRESET handling improved (#17504)

Co-authored-by: pre-commit-ci-lite[bot] <117423508+pre-commit-ci-lite[bot]@users.noreply.github.com>

tests/component_tests/mipi_spi/test_init.py

@@ -361,7 +361,8 @@ def test_native_generation(
         "mipi_spi::MipiSpiBuffer<uint16_t, mipi_spi::PIXEL_MODE_16, true, mipi_spi::PIXEL_MODE_16, mipi_spi::BUS_TYPE_QUAD, 360, 360, 0, 1, 0, 0, 0, true, 1, 1>()"
         in main_cpp
     )
-    assert "set_init_sequence({240, 1, 8, 242" in main_cpp
+    # A 10ms post-reset delay ({10, 255}) is prepended ahead of the model commands.
+    assert "set_init_sequence({10, 255, 240, 1, 8, 242" in main_cpp
     assert "show_test_card();" in main_cpp
     assert "set_write_only(true);" in main_cpp
 
@@ -377,6 +378,76 @@ def test_lvgl_generation(
         "mipi_spi::MipiSpi<uint16_t, mipi_spi::PIXEL_MODE_16, true, mipi_spi::PIXEL_MODE_16, mipi_spi::BUS_TYPE_SINGLE, 128, 160, 0, 0, 0, 0, 0, true>();"
         in main_cpp
     )
-    assert "set_init_sequence({177, 3, 1, 44, 45, 178" in main_cpp
+    # A 10ms post-reset delay ({10, 255}) is prepended ahead of the model commands.
+    assert "set_init_sequence({10, 255, 177, 3, 1, 44, 45, 178" in main_cpp
     assert "show_test_card();" not in main_cpp
     assert "set_auto_clear(false);" in main_cpp
+
+
+# A 10ms delay (flattened to {10, 0xFF}, where 0xFF is the delay marker byte) is
+# always prepended to the init sequence, since both a software and a hardware reset
+# need to settle before further commands. A custom model has no reset_pin default
+# and does not set no_swreset, so when no reset pin is configured the SWRESET command
+# ({1, 0}: command 0x01 with no parameters) is prepended ahead of that delay.
+_SWRESET_YAML = """
+esphome:
+  name: swreset-test
+esp32:
+  board: esp32-s3-devkitc-1
+  framework:
+    type: esp-idf
+spi:
+  clk_pin: 1
+  mosi_pin: 2
+display:
+  - platform: mipi_spi
+    model: custom
+    id: {display_id}
+    dc_pin: 4
+    cs_pin: 8
+    dimensions:
+      width: 320
+      height: 240
+    init_sequence:
+      - [0xA0, 0x01]
+{reset_line}
+"""
+
+
+def test_swreset_prepended_without_reset_pin(
+    generate_main: Callable[[str | Path], str],
+    tmp_path: Path,
+) -> None:
+    """A model with no reset pin (and no no_swreset) gets SWRESET prepended."""
+    yaml_file = tmp_path / "swreset.yaml"
+    yaml_file.write_text(
+        _SWRESET_YAML.format(display_id="swreset_display", reset_line="")
+    )
+
+    main_cpp = generate_main(yaml_file)
+
+    # SWRESET ({1, 0}) followed by a 10ms delay ({10, 255}) is inserted ahead of
+    # the model's own commands.
+    assert "swreset_display->set_init_sequence({1, 0, 10, 255, 160, 1, 1," in main_cpp
+
+
+def test_swreset_not_prepended_with_reset_pin(
+    generate_main: Callable[[str | Path], str],
+    tmp_path: Path,
+) -> None:
+    """A hardware reset pin performs the reset, so SWRESET must not be prepended.
+
+    The post-reset delay is still required, so the sequence starts with the delay.
+    """
+    yaml_file = tmp_path / "hwreset.yaml"
+    yaml_file.write_text(
+        _SWRESET_YAML.format(
+            display_id="hwreset_display", reset_line="    reset_pin: 5"
+        )
+    )
+
+    main_cpp = generate_main(yaml_file)
+
+    # The delay ({10, 255}) is still present, but no leading SWRESET ({1, 0}).
+    assert "hwreset_display->set_init_sequence({10, 255, 160, 1, 1," in main_cpp
+    assert "hwreset_display->set_init_sequence({1, 0," not in main_cpp