RT2661_MGT_RING_COUNT
if (ring->queued >= RT2661_MGT_RING_COUNT) {
ring->cur = (ring->cur + 1) % RT2661_MGT_RING_COUNT;
RT2661_MGT_RING_COUNT);
err = rt2661_alloc_tx_ring(sc, &sc->mgtq, RT2661_MGT_RING_COUNT);