I have searched all over the web and haven't found this pop up that much, I can't find anything in particular that could be causing this wakelock. Once the wakelock starts, it keeps the phone awake 100% of the time. Running CM11 M2 snapshot with various kernels (stock CM, Hells core, AK at the moment) and it appears with all 3 kernels.
I'm running BetterBatteryStats (doesn't show anything aside from pointing out it's 'Slimport Wakelock' and Wakelock detector doesn't even register 'Slimport wakelock' and doesn't seem to show anything rogue....
Nexus 4 on T-mobile
Retired: Galaxy Nexus (worst phone I've had) - iPhone 4 - iPhone 3G - HTC Touch Diamond (MDA Compact IV) - HTC StarTrek (Cingular 3125): WinMo 5!