Qt5.6 eglfs error: WSEGL_CreateWindowDrawable: Couldn't set CRTC: Permission denied

[Zhangs]

Platform: Ti AM437x SDK3.01

I found the qt app can't use eglfs by using the default filesystem provided by TI PSDK3.01.
Here are some error dumps:
root@am437x-evm:~# ./myApp -platform eglfs
...
PVR:(Error): WSEGL_CreateWindowDrawable: Couldn't set CRTC: Permission denied [0, ]
EGL Error : Could not create the egl surface: error = 0x3003

Aborted (core dumped)
root@am437x-evm:~#

But the app can use wayland:
root@am437x-evm:~# ./myApp -platform wayland
...
Using Wayland-EGL
wlpvr: PVR Services Initialised
...
root@am437x-evm:~#

I have serveral questions:

1. How can I use the eglfs correctly?
2. I don't want to use wayland for display since I have patch the Qt souce before which will use EGLFS for display,
   so how can I remove the wayland(scripts, services) and use EGLFS?

Thank you very much!!!