This limitation does not exist in latest kernel. It was removed by this patch-

commit f7978a0c581a8a840a28306f8da43e06e7fef3bf

v2: Added commit id that removes the limitation(Chris Wilson)
V3: Generic way to find if kernel supports this instead of hardcoding gens(Chris Wilson)
v4: Optimize the if block (Daniele)
v5: Use the same context instead of creating a dummy (Chris Wilson)
v6: Changed comment structure and removed extra brackets, local var (Chris Wilson)
v7: Removed some more extra brackets

Cc: Michel Thierry <michel.thierry@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Petri Latvala <petri.latvala@intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>