PLANE_SURF
base = I915_READ(PLANE_SURF(pipe, plane_id)) & 0xfffff000;
I915_WRITE_FW(PLANE_SURF(pipe, plane_id),
POSTING_READ_FW(PLANE_SURF(pipe, plane_id));
I915_WRITE_FW(PLANE_SURF(pipe, plane_id), 0);
POSTING_READ_FW(PLANE_SURF(pipe, plane_id));