Coral PA - devg-coral problem in combination with sharp tft


I’m having problems to get the devg.coral driver working properly with the Sharp panel I’m using. I only get a stable picture of snow after starting the driver. On the other hand the physical connection seems to be fine since Uboot is able to interface the display properly.
The driver is starting and my settings in the conf file seem to be fine since I measured the output signals and signal timing is according to the displays specification.
My driver callup:
io-graphics -dcoral vid=0x10cf,did=0x201e,xres=800,yres=600,bitpp=15,photon,mode_opts=/etc/system/config/coral.media5200.conf -pphoton

and the line in the conf file looks like that:

Did anybody have a similair problem? Any advice?