feat(display): 添加LVGL显示支持和PWM背光控制

添加了完整的LVGL集成支持，包括：

- 在app.overlay中配置显示设备树，添加背光别名和SPI3总线支持
- 集成PWM背光控制，通过pwm-leds子系统管理背光亮度
- 配置LVGL自动初始化和工作队列运行模式
- 实现显示模块的工作队列更新机制，包含UI创建和定时刷新
- 添加详细的LVGL移植说明文档，涵盖设备树配置、调试步骤和常见问题
- 调整分区配置以适应LVGL固件大小需求
- 启用MCUBoot bootloader支持OTA功能

该变更使得系统能够在ST7789V显示屏上正常运行LVGL界面，并通过PWM控制背光。

src/modules/display_module.c

@@ -1,12 +1,10 @@
-#include <stdio.h>
-
 #include <zephyr/device.h>
 #include <zephyr/devicetree.h>
 #include <zephyr/drivers/display.h>
+#include <zephyr/drivers/led.h>
 #include <zephyr/kernel.h>
 
 #include <app_event_manager.h>
-
 #include <lvgl.h>
 #include <lvgl_zephyr.h>
 
@@ -16,14 +14,17 @@
 #include <zephyr/logging/log.h>
 LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);
 
-#define DISPLAY_UPDATE_PERIOD_MS 10
+#define DISPLAY_UPDATE_PERIOD_MS 1000
+#define DISPLAY_BACKLIGHT_BRIGHTNESS 100
 
 struct display_ctx {
 	const struct device *dev;
-	struct k_work_delayable refresh_work;
-	lv_obj_t *hello_label;
+	struct display_capabilities caps;
+	struct k_work_delayable update_work;
+	lv_obj_t *title_label;
 	lv_obj_t *count_label;
 	uint32_t tick_count;
+	bool ui_ready;
 	bool initialized;
 };
 
@@ -31,10 +32,70 @@ static struct display_ctx disp = {
 	.dev = DEVICE_DT_GET(DT_CHOSEN(zephyr_display)),
 };
 
-static void display_refresh_work_fn(struct k_work *work)
+static const struct led_dt_spec display_backlight =
+	LED_DT_SPEC_GET(DT_NODELABEL(backlight));
+
+static void display_schedule_update(k_timeout_t delay)
 {
-	char count_str[12];
-	uint32_t wait_ms;
+#ifdef CONFIG_LV_Z_RUN_LVGL_ON_WORKQUEUE
+	k_work_schedule_for_queue(lvgl_get_workqueue(), &disp.update_work, delay);
+#else
+	k_work_reschedule(&disp.update_work, delay);
+#endif
+}
+
+static int display_backlight_init(void)
+{
+	int err;
+
+	if (!led_is_ready_dt(&display_backlight)) {
+		LOG_WRN("Display backlight device not ready");
+		return 0;
+	}
+
+	/*
+	 * 背光亮度交给 pwm-leds 驱动管理，这样后面如果要做调光、呼吸灯或亮度档位，
+	 * 都可以直接沿用 Zephyr 的 LED/PWM 接口，而不需要再单独碰 PWM 寄存器。
+	 */
+	err = led_set_brightness_dt(&display_backlight, DISPLAY_BACKLIGHT_BRIGHTNESS);
+	if (err) {
+		LOG_ERR("Failed to set backlight brightness: %d", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static void display_create_ui_locked(void)
+{
+	lv_obj_t *screen = lv_screen_active();
+
+	/*
+	 * 先显式设置背景和文字颜色，避免把“有画面但颜色刚好看不见”误判为
+	 * “LVGL 没有刷新”。这里使用高对比度配色，便于快速验证渲染链路。
+	 */
+	lv_obj_set_style_bg_opa(screen, LV_OPA_COVER, LV_PART_MAIN);
+	lv_obj_set_style_bg_color(screen, lv_color_hex(0x102A43), LV_PART_MAIN);
+	lv_obj_set_style_text_color(screen, lv_color_hex(0xF0F4F8), LV_PART_MAIN);
+	lv_obj_clean(screen);
+
+	disp.title_label = lv_label_create(screen);
+	lv_label_set_text(disp.title_label, "Zephyr LVGL running");
+	lv_obj_set_style_text_color(disp.title_label, lv_color_hex(0xF0F4F8), LV_PART_MAIN);
+	lv_obj_align(disp.title_label, LV_ALIGN_CENTER, 0, -16);
+
+	disp.count_label = lv_label_create(screen);
+	lv_label_set_text(disp.count_label, "tick 0");
+	lv_obj_set_style_text_color(disp.count_label, lv_color_hex(0xFFD166), LV_PART_MAIN);
+	lv_obj_align(disp.count_label, LV_ALIGN_CENTER, 0, 16);
+
+	disp.ui_ready = true;
+}
+
+static void display_update_work_fn(struct k_work *work)
+{
+	char count_str[24];
+	lv_color_t bg_color;
 
 	ARG_UNUSED(work);
 
@@ -44,17 +105,21 @@ static void display_refresh_work_fn(struct k_work *work)
 
 	lvgl_lock();
 
-	if ((disp.tick_count % 100U) == 0U) {
-		snprintk(count_str, sizeof(count_str), "%u", disp.tick_count / 100U);
-		lv_label_set_text(disp.count_label, count_str);
+	if (!disp.ui_ready) {
+		display_create_ui_locked();
 	}
 
-	wait_ms = lv_timer_handler();
+	bg_color = ((disp.tick_count & 0x01u) == 0U) ? lv_color_hex(0x102A43) :
+						 lv_color_hex(0x1F6F8B);
+	lv_obj_set_style_bg_color(lv_screen_active(), bg_color, LV_PART_MAIN);
+
+	snprintk(count_str, sizeof(count_str), "tick %u", disp.tick_count++);
+	lv_label_set_text(disp.count_label, count_str);
+	lv_obj_invalidate(lv_screen_active());
+
 	lvgl_unlock();
 
-	disp.tick_count++;
-	k_work_reschedule(&disp.refresh_work,
-			  K_MSEC(MAX(wait_ms, DISPLAY_UPDATE_PERIOD_MS)));
+	display_schedule_update(K_MSEC(DISPLAY_UPDATE_PERIOD_MS));
 }
 
 static int display_demo_init(void)
@@ -66,22 +131,13 @@ static int display_demo_init(void)
 		return -ENODEV;
 	}
 
+	display_get_capabilities(disp.dev, &disp.caps);
+	LOG_INF("Display caps: %ux%u fmt=%d", disp.caps.x_resolution, disp.caps.y_resolution,
+		disp.caps.current_pixel_format);
+
+	k_work_init_delayable(&disp.update_work, display_update_work_fn);
 	disp.tick_count = 0U;
-	k_work_init_delayable(&disp.refresh_work, display_refresh_work_fn);
-
-	lvgl_lock();
-	lv_obj_clean(lv_screen_active());
-
-	disp.hello_label = lv_label_create(lv_screen_active());
-	lv_label_set_text(disp.hello_label, "LVGL demo running");
-	lv_obj_align(disp.hello_label, LV_ALIGN_CENTER, 0, -12);
-
-	disp.count_label = lv_label_create(lv_screen_active());
-	lv_label_set_text(disp.count_label, "0");
-	lv_obj_align(disp.count_label, LV_ALIGN_BOTTOM_MID, 0, -12);
-
-	lv_timer_handler();
-	lvgl_unlock();
+	disp.ui_ready = false;
 
 	err = display_blanking_off(disp.dev);
 	if (err) {
@@ -89,10 +145,15 @@ static int display_demo_init(void)
 		return err;
 	}
 
-	disp.initialized = true;
-	k_work_reschedule(&disp.refresh_work, K_MSEC(DISPLAY_UPDATE_PERIOD_MS));
+	err = display_backlight_init();
+	if (err) {
+		return err;
+	}
 
+	disp.initialized = true;
+	display_schedule_update(K_NO_WAIT);
 	LOG_INF("LVGL display demo initialized");
+
 	return 0;
 }