屏幕黑下去後，再按POWER鍵只有背光沒有圖像

按POWER鍵進入idle模式時，logcat輸出：

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

出錯了。 開始搜索SurfaceFlinger中的VT_RELDISP,然後結合kernel中對此參數的

處理，沒有發現什麼有價值的東西，然後追蹤最後一句：

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$ 

目標文件中包含字符，可源代碼中沒有搜索到，於是縮短些搜索：

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$ 

這下終於有帶.c的文件了，查看 kernel/power/Makefile

obj-$(CONFIG_FB_EARLYSUSPEND)   += fbearlysuspend.o

查看kernel根目錄下的.config

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

CONFIG_FB_EARLYSUSPEND=y

然後再查看之前android2.2內核2.6.32.9中的這項

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

# CONFIG_FB_EARLYSUSPEND is not set

於是

Power management options  --->

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

         ( ) None                                           

         (X) Console switch on early-suspend

         ( ) Sysfs interface     

編譯燒寫，OK！

BTW:

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

此選項需要先選中

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