1.先用modetest –c確定omapdrm是否正常load了這個只是檢查kernel部分display是否正常初始化
2.如果1是有的那麼看android 有沒有找到display在adb裡面dumpsys SurfaceFlinger如果顯示類似如下資訊，說明有了，不然的幾沒有
h/w composer state:
h/w composer present and enabled
Hardware Composer state (version 1020000):
mDebugForceFakeVSync=0
Display[0] : 720x1280, xdpi=338.665985, ydpi=342.230988, refresh=17241379
numHwLayers=3, flags=00000000
type | handle | hints | flags | tr | blend | format | source crop | frame name
------------+----------+----------+----------+----+-------+----------+---------------------------+--------------------------------
HWC | 65ee32a0 | 00000000 | 00000000 | 04 | 00100 | 7fa00e00 | [ 0, 0, 1280, 720] | [ 0, 0, 720, 1280] SurfaceView
HWC | 65633910 | 00000000 | 00000000 | 00 | 00105 | 00000005 | [ 0, 0, 720, 1280] | [ 0, 0, 720, 1280] com.android.gallery3d/com.android.gallery3d.app.MovieActivity
FB TARGET | 5e95a580 | 00000000 | 00000000 | 00 | 00105 | 00000005 | [ 0, 0, 720, 1280] | [ 0, 0, 720, 1280] HWC_FRAMEBUFFER_TARGET
-------------Display Stat --------------

3.如果android部分沒有檢測到display用下面的command讓HDMI作為primary display。看看是不是HDMI哈。
HDMI
HDMI only setup
By default dual display is supported in this release, but to bring up a HDMI only setup,
• Non lcd dtb for the EVM should be used (Ex: For J6 EVM, use dra7-evm.dtb)
• you need to set two additional properties
• ro.hwc.primary.conn
• ro.hwc.external.conn
Use below commands to set the property and reboot the EVM.
adb root
adb remount
adb shell 'echo "ro.hwc.primary.conn=HDMI" >> /system/build.prop'
adb shell 'echo "ro.hwc.external.conn=dummy" >> /system/build.prop'