Framebuffer resolution not used on embedded arm (cut off )

Hi,
cross compiled qt 5.4.1 using linuxfb /app -platform linuxfb:/dev/fb0

does not use full screen size of the framebuffer.
It is shown as a cut off display (2/3 of display is only used).

If i compile code with 4.8.6 qmake on the same embedded arm platform the linuxfb is fully used no cut off.

It seems qt5 does not detect the linuxFB size correct.