AST_VHUB_EP_ACK_IER
writel(0, vhub->regs + AST_VHUB_EP_ACK_IER);
ep_ier = readl(vhub->regs + AST_VHUB_EP_ACK_IER);
writel(ep_ier, vhub->regs + AST_VHUB_EP_ACK_IER);
ep_ier = readl(vhub->regs + AST_VHUB_EP_ACK_IER);
writel(ep_ier, vhub->regs + AST_VHUB_EP_ACK_IER);