During ring initialisation, sometimes we observe, though not in
production hardware, that the idle flag is not set even though the ring
is empty. Double check before giving up.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Cc: Damien Lespiau <damien.lespiau@intel.com>
Reviewed-by: NDamien Lespiau <damien.lespiau@intel.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>