Author: Chris Wilson <chris@chris-wilson.co.uk> Otherwise we get flooded by the kernel warning us that we are doing long sequences of IO without serialisation. For example, WARNING: CPU: 0 PID: 11136 at drivers/gpu/drm/i915/intel_sideband.c:40 vlv_sideband_rw+0x48/0x1ef() Modules linked in: CPU: 0 PID: 11136 Comm: kworker/u2:0 Tainted: G W 3.11.0-rc2+ #4 Call Trace: [] ? warn_slowpath_common+0x63/0x78 [] ? vlv_sideband_rw+0x48/0x1ef …