How to change pcie link speed to gen2.0 on xavier nx modules?

Hi team, I am using R35.1 on xavier nx module, custom currier board. I flashed the os on nvme disk, now pcie link up on gen3 , I want to know how to change the link speed to gen2 ?

root@w:~# lspci -s 0005:01:00.0

0005:01:00.0 Non-Volatile memory controller: Device 0000:8111 (rev 01)

root@w:~# 

root@w:~# 

root@w:~# lspci -s 0005:01:00.0 -vv | grep LnkSta

		LnkSta:	Speed 8GT/s (ok), Width x4 (ok)

		LnkSta2: Current De-emphasis Level: -6dB, EqualizationComplete+, EqualizationPhase1+

root@w:~# 

root@w:~# dmesg | grep "0005:01:00"

[    4.809080] pci 0005:01:00.0: [0000:8111] type 00 class 0x010802

[    4.809514] pci 0005:01:00.0: reg 0x10: [mem 0x00000000-0x00003fff 64bit]

[    4.821266] pci 0005:01:00.0: BAR 0: assigned [mem 0x1f40000000-0x1f40003fff 64bit]

[    4.822633] pci 0005:01:00.0: Max Payload Size set to  256/ 256 (was  128), Max Read Rq  512

[    4.833886] nvme 0005:01:00.0: Adding to iommu group 6

[    4.839151] nvme nvme0: pci function 0005:01:00.0

[    4.842189] nvme 0005:01:00.0: enabling device (0000 -> 0002)

root@w:~# 

root@w:~# 

root@w:~# dmesg | grep "141a0000.pcie"

[    4.646376] tegra194-pcie 141a0000.pcie: Adding to iommu group 6

[    4.655402] tegra194-pcie 141a0000.pcie: host bridge /pcie@141a0000 ranges:

[    4.656617] tegra194-pcie 141a0000.pcie:       IO 0x003a100000..0x003a1fffff -> 0x003a100000

[    4.665564] tegra194-pcie 141a0000.pcie:      MEM 0x1c00000000..0x1f3fffffff -> 0x1c00000000

[    4.673919] tegra194-pcie 141a0000.pcie:      MEM 0x1f40000000..0x1fffffffff -> 0x0040000000

[    4.791740] tegra194-pcie 141a0000.pcie: Link up

[    4.794488] tegra194-pcie 141a0000.pcie: PCI host bridge to bus 0005:00