feat(lcd): add brightness control for LCD panels

Merges https://github.com/espressif/esp-idf/pull/18273
Closes https://github.com/espressif/esp-idf/issues/16230

components/esp_lcd/include/esp_lcd_panel_ops.h

@@ -157,6 +157,17 @@ esp_err_t esp_lcd_panel_disp_on_off(esp_lcd_panel_handle_t panel, bool on_off);
  */
 esp_err_t esp_lcd_panel_disp_sleep(esp_lcd_panel_handle_t panel, bool sleep);
 
+/**
+ * @brief Set the brightness of the display
+ *
+ * @param[in] panel LCD panel handle, which is created by other factory API like `esp_lcd_new_panel_st7789()`
+ * @param[in] brightness Brightness value (range depends on panel implementation, typically 0-255, 0-1023, or 0-100)
+ * @return
+ *          - ESP_OK on success
+ *          - ESP_ERR_NOT_SUPPORTED if this function is not supported by the panel
+ */
+esp_err_t esp_lcd_panel_set_brightness(esp_lcd_panel_handle_t panel, int brightness);
+
 #ifdef __cplusplus
 }
 #endif

components/esp_lcd/interface/esp_lcd_panel_interface.h

@@ -152,6 +152,17 @@ struct esp_lcd_panel_t {
      */
     esp_err_t (*disp_sleep)(esp_lcd_panel_t *panel, bool sleep);
 
+    /**
+     * @brief Set the brightness of the display
+     *
+     * @param[in] panel LCD panel handle, which is created by other factory API like `esp_lcd_new_panel_st7789()`
+     * @param[in] brightness Brightness value (range depends on panel implementation, typically 0-255, 0-1023, or 0-100)
+     * @return
+     *          - ESP_OK on success
+     *          - ESP_ERR_NOT_SUPPORTED if this function is not supported by the panel
+     */
+    esp_err_t (*set_brightness)(esp_lcd_panel_t *panel, int brightness);
+
     void *user_data;    /*!< User data, used to store externally customized data */
 };
 

components/esp_lcd/src/esp_lcd_panel_ops.c

@@ -88,3 +88,10 @@ esp_err_t esp_lcd_panel_disp_sleep(esp_lcd_panel_handle_t panel, bool sleep)
     ESP_RETURN_ON_FALSE(panel->disp_sleep, ESP_ERR_NOT_SUPPORTED, TAG, "sleep is not supported by this panel");
     return panel->disp_sleep(panel, sleep);
 }
+
+esp_err_t esp_lcd_panel_set_brightness(esp_lcd_panel_handle_t panel, int brightness)
+{
+    ESP_RETURN_ON_FALSE(panel, ESP_ERR_INVALID_ARG, TAG, "invalid panel handle");
+    ESP_RETURN_ON_FALSE(panel->set_brightness, ESP_ERR_NOT_SUPPORTED, TAG, "set_brightness is not supported by this panel");
+    return panel->set_brightness(panel, brightness);
+}

components/esp_lcd/src/esp_lcd_panel_st7789.c

@@ -40,6 +40,7 @@ static esp_err_t panel_st7789_invert_color(esp_lcd_panel_t *panel, bool invert_c
 static esp_err_t panel_st7789_mirror(esp_lcd_panel_t *panel, bool mirror_x, bool mirror_y);
 static esp_err_t panel_st7789_swap_xy(esp_lcd_panel_t *panel, bool swap_axes);
 static esp_err_t panel_st7789_set_gap(esp_lcd_panel_t *panel, int x_gap, int y_gap);
+static esp_err_t panel_st7789_set_brightness(esp_lcd_panel_t *panel, int brightness);
 static esp_err_t panel_st7789_disp_on_off(esp_lcd_panel_t *panel, bool off);
 static esp_err_t panel_st7789_sleep(esp_lcd_panel_t *panel, bool sleep);
 
@@ -125,6 +126,7 @@ esp_lcd_new_panel_st7789(const esp_lcd_panel_io_handle_t io, const esp_lcd_panel
     st7789->base.draw_bitmap = panel_st7789_draw_bitmap;
     st7789->base.invert_color = panel_st7789_invert_color;
     st7789->base.set_gap = panel_st7789_set_gap;
+    st7789->base.set_brightness = panel_st7789_set_brightness;
     st7789->base.mirror = panel_st7789_mirror;
     st7789->base.swap_xy = panel_st7789_swap_xy;
     st7789->base.disp_on_off = panel_st7789_disp_on_off;
@@ -287,6 +289,18 @@ static esp_err_t panel_st7789_set_gap(esp_lcd_panel_t *panel, int x_gap, int y_g
     return ESP_OK;
 }
 
+static esp_err_t panel_st7789_set_brightness(esp_lcd_panel_t *panel, int brightness)
+{
+    st7789_panel_t *st7789 = __containerof(panel, st7789_panel_t, base);
+    esp_lcd_panel_io_handle_t io = st7789->io;
+    ESP_RETURN_ON_FALSE(brightness >= 0 && brightness <= 0xFF, ESP_ERR_INVALID_ARG, TAG,
+                        "brightness out of range");
+    uint8_t brightness_value = (uint8_t)brightness;
+    ESP_RETURN_ON_ERROR(esp_lcd_panel_io_tx_param(io, LCD_CMD_WRDISBV, &brightness_value, 1), TAG,
+                        "io tx param failed");
+    return ESP_OK;
+}
+
 static esp_err_t panel_st7789_disp_on_off(esp_lcd_panel_t *panel, bool on_off)
 {
     st7789_panel_t *st7789 = __containerof(panel, st7789_panel_t, base);