NVMe M.2 configured as single lane PCIe

[wolfcoder90]

I am using Jetson Orin Nano devkit with Jetpack 5.1.2. I found the M2. hase configured as single lane PCIe. But according to the documentation it can be configured as 4 lane PCIe. Do I have enable it or change it in device -tree ?

jetson@nvidia:~$ ls /sys/bus/pci/devices/000
0001:00:00.0/ 0001:01:00.0/ 0004:00:00.0/ 0004:01:00.0/ 0008:00:00.0/ 0008:01:00.0/
jetson@nvidia:~$ cat /sys/bus/pci/devices/0008:01:00.0/current_link_width
1
jetson@nvidia:~$ cat /sys/bus/pci/devices/0008:01:00.0/current_link_speed
2.5 GT/s PCIe

[WayneWWW]

Orin Nano only support to PCIe GEN3.

For your problem, it has nothing to do with device tree either. The speed is the result of PCIe link training. You could try other SSD first and see if this only happened to specific NVMe.

[wolfcoder90]

So this PCIe link training is for one lane ? and actually its connected all four lane ? Also in devkit there are two M.2 socket for NVMe. Are these 4 lanes devided into 2 lanes as per socket ?

[WayneWWW]

Yes.
It is the pcie link training somehow only gives out 2.5GT speed with the PCIe device you are using and it is a downgraded one.

Changing to other devices may give out a higher speed due to another link training result.

For the two M.2 socket for NVME, the C4 one is a x4 lane design and the C7 one is a x2 lane design.