I have had this problem for a while. I have a usecase where I require the touch-functionality and the OpenGL-support. I tried with the inofficial version of Anholds driver and it didnt work and now, that the official version was released i tried again. When I enable OpenGL support in rapi-config I can only use HDMI-displays anymore. The DSI interface does not seem to work with the dirver. Even if I only connect the official 7'' display - it only boots to the driver-splashscreen (the colorfull loading screen). If I connect a monitor via HDMI it uses this one instead and the 7'' display is only powered on (backlight is active - screen is black)
Do you have any suggestions what I am doing wrong?