I'm on Yosemite public beta. I got everything working except the screen brightness control. I tried the GenericBrightness.kext as well as the noSlider applications (patches applied). Nothing seems to work! Then I tried rehabman's patches. I got to a point where I can control my display brightness but my laptop's screen remains black. The external display works fine though.
Specs: Toshiba p750 satellite, core i7 sandybridge, intel HD3000 512mb + nvidia 540m 2gb.
Here is my DSDT..