The link status of the 82599 NIC cannot be setted to down

[wangyunjian]

Hi All,
   It is expected that the ixgbe_dev_set_link_down function is called to make
the link status of the NIC down. However, the invoking is successful, but
link status is still up. Anyone have some good ideas?

dpdk version:DPDK 21.11
firmware-version:0x800006d5
NIC:Intel Corporation 82599 10 Gigabit Dual Port Backplane Connection (rev 01)