BGMAC_DMA_RX_CTL
bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_CTL, 0);
ctl = bgmac_read(bgmac, ring->mmio_base + BGMAC_DMA_RX_CTL);
bgmac_write(bgmac, ring->mmio_base + BGMAC_DMA_RX_CTL, ctl);