https://www.amazon.com/gp/product/B01ID5BQTC/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1 So I just picked up one of these screens and I’m not sure where to start with getting the touch screen to play nice. The display works real nice once I set the screen rotation but I have no clue how to update the drivers. If someone could point me in the right direction I would be very appreciative. And yes I know the new Manga screen is coming out but i need instant gratification 
If it helps any it is supposed to work with Angstrom out of the box…
Might be the older style waveshare touchscreens, if so you cant do much except try to make your own driver. Try plugging it in to your computer and see if i registers as a bar-code-scanner or a touch screen
http://www.waveshare.com/wiki/7inch_HDMI_LCD_(B)
This is supposed to be a fix but i’m not smart enough to get it to work. https://github.com/derekhe/waveshare-7inch-touchscreen-driver