MBUS_MDFSCR
writel(mdfscr, priv->reg_mbus + MBUS_MDFSCR);
writel(mdfscr | MBUS_MDFSCR_START, priv->reg_mbus + MBUS_MDFSCR);
ret = readl_poll_timeout_atomic(priv->reg_mbus + MBUS_MDFSCR, mdfscr,
writel(0, priv->reg_mbus + MBUS_MDFSCR);