SAR_CFG_FBIE
writel(readl(SAR_REG_CFG) & ~(SAR_CFG_FBIE), SAR_REG_CFG);
writel(readl(SAR_REG_CFG) | SAR_CFG_FBIE, SAR_REG_CFG);
SAR_CFG_FBIE | /* interrupt on low free buffers */
SAR_CFG_FBIE | /* interrupt on low free buffers */