diff --git a/bsp/qemu-vexpress-a9/applications/main.c b/bsp/qemu-vexpress-a9/applications/main.c
index e8ef51657e064d8e14d4157744ff9e36dddab4d3..b9364eee2fc505df10e581a50f45b267590adf27 100644
--- a/bsp/qemu-vexpress-a9/applications/main.c
+++ b/bsp/qemu-vexpress-a9/applications/main.c
@@ -14,7 +14,7 @@
 
 int main(void)
 {
-    printf("hello rt-thread\n");
+    printf("Hello RT-Thread!\n");
 
     return 0;
 }
diff --git a/bsp/qemu-vexpress-a9/drivers/drv_clcd.c b/bsp/qemu-vexpress-a9/drivers/drv_clcd.c
index 2d012dca84c161c52cf7755bec01a43a93859300..3fe2bd58d34a185e94b49e1f2ac7143b9cc4ba8b 100644
--- a/bsp/qemu-vexpress-a9/drivers/drv_clcd.c
+++ b/bsp/qemu-vexpress-a9/drivers/drv_clcd.c
@@ -75,13 +75,15 @@ static rt_err_t drv_clcd_control(struct rt_device *device, int cmd, void *args)
 
             RT_ASSERT(info != RT_NULL);
             info->pixel_format  = RTGRAPHIC_PIXEL_FORMAT_RGB565;
-            // info->pixel_format  = RTGRAPHIC_PIXEL_FORMAT_ARGB888;
             info->bits_per_pixel= 16;
             info->width         = lcd->width;
             info->height        = lcd->height;
             info->framebuffer   = lcd->fb;
         }
         break;
+
+    default:
+        return -RT_EINVAL;
     }
 
     return RT_EOK;
@@ -109,7 +111,7 @@ int drv_clcd_hw_init(void)
 
     _lcd.width  = CLCD_WIDTH;
     _lcd.height = CLCD_HEIGHT;
-    _lcd.fb     = rt_malloc(_lcd.width * _lcd.height * 2);
+    _lcd.fb     = rt_malloc(_lcd.width * _lcd.height * 2 /*RGB565 2 Bytes*/);
     if (_lcd.fb == NULL)
     {
         rt_kprintf("initialize frame buffer failed!\n");
diff --git a/bsp/stm32/libraries/HAL_Drivers/drv_lcd.c b/bsp/stm32/libraries/HAL_Drivers/drv_lcd.c
index 96c61835e66d1eeb6f1ab2c9ab2a1b5f60a5e748..a0db14fc1af2c83ccb3540d9802c54d267acd848 100644
--- a/bsp/stm32/libraries/HAL_Drivers/drv_lcd.c
+++ b/bsp/stm32/libraries/HAL_Drivers/drv_lcd.c
@@ -90,6 +90,9 @@ static rt_err_t drv_lcd_control(struct rt_device *device, int cmd, void *args)
         info->framebuffer   = lcd->lcd_info.framebuffer;
     }
     break;
+
+    default:
+        return -RT_EINVAL;
     }
 
     return RT_EOK;