The ocl example facedetect based on haar features returns no correct results when using the Intel platform with both Windows and Linux OpenCL, but can work fine on Nvidia or AMD OpenCL. Then if I comment all the codes related with FEATURE_CL_INTEL_DEVICE in /modules/ocl/src/haar.cpp the sample can still work fine on Intel platform.
(See related "pull request #1675":https://github.com/Itseez/opencv/pull/1675)