WPI_CMD_RING_COUNT
ring->cur = (ring->cur + 1) % WPI_CMD_RING_COUNT;
ring->cur = (ring->cur + 1) % WPI_CMD_RING_COUNT;
ring->cur = (ring->cur + 1) % WPI_CMD_RING_COUNT;
error = wpi_alloc_tx_ring(sc, &sc->cmdq, WPI_CMD_RING_COUNT, 4);