Uboot启动logo修改
使用Uboot版本
2016.03.10
修改Uboot启动logo需要的操作
（1）.修改tools目录下的Makefile文件的如下部分：
# Use board logo and fallback to vendor
ifneq ($(wildcard $(srctree)/$(src)/logos/$(BOARD).bmp),)
LOGO_BMP= $(srctree)/$(src)/logos/$(BOARD).bmp
else
ifneq ($(wildcard $(srctree)/$(src)/logos/$(VENDOR).bmp),)
LOGO_BMP= $(srctree)/$(src)/logos/$(VENDOR).bmp
可以将 $(VENDOR).bmp的这个名字，替换为自制的logo的bmp 图片的名字。
（2）.在Uboot的可配置裁剪文件中，确定有如下宏是被定义的：
#define CONFIG_CFB_CONSOLE
#define CONFIG_VIDEO_MXS
#define CONFIG_VIDEO_LOGO
#define CONFIG_VIDEO_SW_CURSOR
#define CONFIG_VGA_AS_SINGLE_DEVICE
#define CONFIG_SYS_CONSOLE_IS_IN_ENV
#define CONFIG_SPLASH_SCREEN
#define CONFIG_SPLASH_SCREEN_ALIGN
#define CONFIG_CMD_BMP
#define CONFIG_BMP_16BPP
#define CONFIG_VIDEO_BMP_RLE8
#define CONFIG_VIDEO_BMP_LOGO
#define CONFIG_IMX_VIDEO_SKIP
（3）.重新编译Uboot，然后再次烧写，然后Uboot启动显示的就会是自制的logo了。
Uboot显示logo详解
Uboot显示logo的详细流程
LCD的初始化在uboot启动的第二阶段，在init_sequence_r函数指针数组里。
函数调用过程如下：
····board_init_r： common/board_r.c
········stdio_add_devices：common/stdio.c
············drv_video_init：drivers/video/cfb_console.c
················int board_video_skip：arch/arm/imx-common/video.c
····················void select_display_dev：board/freescale/mx6ullevk/mx6ullevk.c
················video_init：drivers/video/cfb_console.c
····················dcache_status:arch/arm/lib/cache-cp15.c
················video_clear：drivers/video/cfb_console.c
················video_logo:drivers/video/cfb_console.c
····················splash_get_pos:common/splash.c
····················do_fat_fsload：cmd/fat.c
····················splash_screen_prepare:common/splash.c
····················video_display_bitmap:drivers/video/cfb_console.c
····················logo_plot：drivers/video/cfb_console.c
························plot_logo_or_black：drivers/video/cfb_console.c
················board_cfb_skip:drivers/video/cfb_console.c