fix(drivers): generic MIPI add missing lv_display_flush_ready (#7693)

docs/details/integration/driver/display/gen_mipi.rst

@@ -118,6 +118,12 @@ Example
 	static void my_lcd_send_color(lv_display_t *disp, const uint8_t *cmd, size_t cmd_size, uint8_t *param, size_t param_size)
 	{
 		...
+
+		/* This must be called to signal that the transfer has finished.
+		 * It is typically called in a "DMA transfer complete" callback
+		 * long after `my_lcd_send_color` has returned.
+		 */
+		lv_display_flush_ready(disp);
 	}
 
 	int main(int argc, char ** argv)

src/drivers/display/lcd/lv_lcd_generic_mipi.c

@@ -160,6 +160,7 @@ static void send_color(lv_lcd_generic_mipi_driver_t * drv, uint8_t cmd, uint8_t
 {
     uint8_t cmdbuf = cmd;       /* MIPI uses 8 bit commands */
     drv->send_color(drv->disp, &cmdbuf, 1, param, param_size);
+    /* note: LVGL waits for your callback to call `lv_display_flush_ready` to know when the transfer has finished. */
 }
 
 /**

src/drivers/display/lcd/lv_lcd_generic_mipi.h

@@ -179,7 +179,8 @@ typedef struct {
  * @param ver_res       vertical resolution
  * @param flags         default configuration settings (mirror, RGB ordering, etc.)
  * @param send_cmd      platform-dependent function to send a command to the LCD controller (usually uses polling transfer)
- * @param send_color    platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer: must implement a 'ready' callback)
+ * @param send_color    platform-dependent function to send pixel data to the LCD controller (usually uses DMA transfer).
+ *                      `lv_display_flush_ready` must be called after the transfer has finished.
  * @return              pointer to the created display
  */
 lv_display_t * lv_lcd_generic_mipi_create(uint32_t hor_res, uint32_t ver_res, lv_lcd_flag_t flags,