DMA_CHAN_TX_RING_LEN
reg_space[DMA_CHAN_TX_RING_LEN(default_addrs, channel) / 4] =
readl(ioaddr + DMA_CHAN_TX_RING_LEN(dwmac4_addrs, channel));
writel(len, ioaddr + DMA_CHAN_TX_RING_LEN(dwmac4_addrs, chan));