I am trying to tune the USB2 port on a custom board but I can’t access any of the registers described in the guide (echo on > /sys/bus/usb/devices/usb1/power/control)or using tegra_hc_port_test_v3_static. With the echo command I get permission denied when using sudo or not, the executable can’t open /sys/devices/platform/tegra-xhci and I can’t find that either.
Is there source code to the executable available so it can be modified when we figure out the issue?
Hi lloyd_j_strickler,
Do you plugin in the scope? The device nodes should be present once the device is detected. You should see it detected as USB device in dmesg.
The scope was plugged in and so was the USB hub or memory stick plugged into the USB port. I tried it without anything attached and all 3 possible ports in each condition (hub, memory, nothing). I can see the USB3 eye diagram with nothing attached but the scope thru one of the testing adapters and it looks good.
Command sent:
sudo echo on > /sys/bus/usb/devices/usb1/power/control
Response received:
-bash: /sys/bus/usb/devices/usb2/power/control: Permission denied