I had no control of brightness on both edition of kali linux 2.0 and now Rolling. I found a simple fix for hp laptops with mod to grub file. But when I installed Nvidia driver and disable nouvea not only could I not control brightness...my brightness control slider was completely missing. Fn buttons nothing work.Three days of trying xbacklight and xcalib which worked to a certain degree , I kept seeing Nvidia control panel on 4 , 5 years old youtube videos on fixing this very same problem. I have Nvidia so where is my control panel. After searching my app drawer for anything related to Nvidia I found Nvidia X server app. And sure enough after clicking on every tab and scroll down I found it ! Open server setting in app...scroll down to DFP-o- (LGD)...click correction tab...BAM ! brightness , contrast , and gamma. My brightness was at default level but least than a third of brightness was being supplied. I have the same laptop that I had kali linux 2.0 on so the answer was there all the time just did not know where to look.