No image when using LVDS display


I’m using cm3-io where I’ve added support for LVDS display and everything works fine. I’ve added mender support for my board and when booting Image + dtb only LVDS is not working. I see that fb0 is found but display is just black (tried with dd if=/dev/urandom of=/dev/fb0). Any idea what can be the difference to boot stock yocto image and Image only? Thansk.