NVREG_PFF_PAUSE_RX
u32 pff = readl(base + NvRegPacketFilterFlags) & NVREG_PFF_PAUSE_RX;
u32 pff = readl(base + NvRegPacketFilterFlags) & ~NVREG_PFF_PAUSE_RX;
writel(pff|NVREG_PFF_PAUSE_RX, base + NvRegPacketFilterFlags);