屏幕黑下去后，再按POWER键只有背光没有图像

按POWER键进入idle模式时，logcat输出：

request_suspend_state: sleep (0->3) at 26963560170 (2010-01-01 12:00:26.982533335 UTC)

IT7260_ts_i2c call suspend

I/power   (   72): *** set_screen_state 0

D/SurfaceFlinger(   72): About to give-up screen, flinger = 0x20b430

E/SurfaceFlinger(   72): ioctl(27, VT_RELDISP, 1) failed 22 (Invalid argument)

stop_drawing_early_suspend: timeout waiting for userspace to stop drawing

出错了。 开始搜索SurfaceFlinger中的VT_RELDISP,然后结合kernel中对此参数的

处理，没有发现什么有价值的东西，然后追踪最后一句：

stop_drawing_early_suspend: timeout waiting for userspace to stop drawing

jeff@microlink-desktop:kernel$ grep "timeout waiting for userspace to stop drawing" . -r

Binary file ./.tmp_vmlinux1 matches

Binary file ./vmlinux matches

Binary file ./.tmp_vmlinux2 matches

Binary file ./vmlinux.o matches

Binary file ./arch/arm/boot/Image matches

Binary file ./kernel/built-in.o matches

Binary file ./kernel/power/built-in.o matches

Binary file ./kernel/power/fbearlysuspend.o matches

jeff@microlink-desktop:kernel$ 

目标文件中包含字符，可源代码中没有搜索到，于是缩短些搜索：

jeff@microlink-desktop:kernel$ grep "to stop drawing" . -r                                      

Binary file ./.tmp_vmlinux1 matches

Binary file ./vmlinux matches

Binary file ./.tmp_vmlinux2 matches

Binary file ./vmlinux.o matches

Binary file ./arch/arm/boot/Image matches

Binary file ./kernel/built-in.o matches

Binary file ./kernel/power/built-in.o matches

./kernel/power/fbearlysuspend.c:/* tell userspace to stop drawing, wait for it to stop */

./kernel/power/fbearlysuspend.c:                           "userspace to stop drawing\n");

Binary file ./kernel/power/fbearlysuspend.o matches

jeff@microlink-desktop:kernel$ 

这下终于有带.c的文件了，查看 kernel/power/Makefile

obj-$(CONFIG_FB_EARLYSUSPEND)   += fbearlysuspend.o

查看kernel根目录下的.config

jeff@microlink-desktop:kernel$ cat .config | grep "CONFIG_FB_EARLYSUSPEND"

CONFIG_FB_EARLYSUSPEND=y

然后再查看之前android2.2内核2.6.32.9中的这项

jeff@microlink-desktop:kernel$ cat .config | grep "CONFIG_FB_EARLYSUSPEND"

# CONFIG_FB_EARLYSUSPEND is not set

于是

Power management options  --->

   User-space screen access (Sysfs interface)  --->

         ( ) None                                           

         (X) Console switch on early-suspend

         ( ) Sysfs interface     

编译烧写，OK！

BTW:

Device Drivers ->Graphics support  --->Console display driver support  ---> 

此选项需要先选中

Device Drivers ->Character devices  --->[*] Virtual terminal