https://bugs.freedesktop.org/show_bug.cgi?id=91540
--- Comment #5 from Michel Dänzer michel@daenzer.net --- (In reply to Bas Nieuwenhuizen from comment #4)
I tested this again with the agd5f/linux drm-next-4.3 branch and this bug did not occur anymore.
Is it really completely gone for you? I still seem to be seeing at least a mild variation of the problem after bootup, though sometimes it seems to disappear by itself after a while now.