USB Error -71 / Implications of old_scheme_first=Y Solution

I have a Simply Automated USB Computer Interface Module for Universal Powerline Bus (UPB) [Model UMC-USB-W] that wasn't getting recognized by Unraid. (Excessive detail included to facilitate search by others with this device).

Snip of error log was:

Oct  3 12:37:09 Unraid kernel: usb 3-2: new low-speed USB device number 44 using xhci_hcd
Oct  3 12:37:09 Unraid kernel: usb 1-6.4: USB disconnect, device number 23
Oct  3 12:37:10 Unraid kernel: hid-generic 0003:17DD:5500.0947: hiddev97,hidraw1: USB HID v1.00 Device [Simply Automated Inc. USB to Serial] on usb-0000:09:00.3-2/input0
Oct  3 12:37:10 Unraid kernel: usb 3-2: USB disconnect, device number 44
Oct  3 12:37:10 Unraid kernel: usb 1-6.4: new low-speed USB device number 24 using xhci_hcd
Oct  3 12:37:10 Unraid kernel: usb 1-6.4: can't set config #1, error -71
Oct  3 12:37:10 Unraid kernel: usb 3-2: new low-speed USB device number 45 using xhci_hcd
Oct  3 12:37:10 Unraid kernel: usb 1-6.4: USB disconnect, device number 24
Oct  3 12:37:10 Unraid kernel: hid-generic 0003:17DD:5500.0948: hiddev97,hidraw1: USB HID v1.00 Device [Simply Automated Inc. USB to Serial] on usb-0000:09:00.3-2/input0

I was able to get it working by:

echo Y >/sys/module/usbcore/parameters/old_scheme_first

NOTE: It seems that a common recommendation is to set use_both_schemes=Y to resolve this. On my system, use_both_schemes=Y was already in place, but old_scheme_first=N. Taking a shot in the dark, I set old_scheme_first=Y. It seems to have the desired effect.

After making the change, I unplugged the USB device and reinserted it. Resulting log is with no subsequent errors:

Oct  3 12:59:19 Unraid kernel: hid-generic 0003:17DD:5500.094C: hiddev97,hidraw1: USB HID v1.00 Device [Simply Automated Inc. USB to Serial] on usb-0000:0e:00.3-4/input0

I am also able to access device information:

root@Unraid:/sys/module/usbcore/parameters# lsusb
Bus 008 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 007 Device 003: ID 17dd:5500 Simply Automated Inc. USB to Serial
Bus 007 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 006 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 005 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 002: ID 1058:0741 Western Digital Technologies, Inc. My Passport Ultra
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 004: ID 0781:5571 SanDisk Corp. Cruzer Fit
Bus 003 Device 003: ID 05e3:0608 Genesys Logic, Inc. Hub
Bus 003 Device 002: ID 8087:0029 Intel Corp. 
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 05e3:0608 Genesys Logic, Inc. Hub
Bus 001 Device 002: ID 048d:8297 Integrated Technology Express, Inc. ITE Device(8595)
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
root@Unraid:/sys/module/usbcore/parameters# udevadm info /dev/bus/usb/007/003 | egrep "ID_VENDOR=|ID_MODEL=|PRODUCT"
E: ID_MODEL=USB_to_Serial
E: ID_VENDOR=Simply_Automated_Inc.
E: PRODUCT=17dd/5500/0
root@Unraid:/sys/module/usbcore/parameters# 

Are there any negative consequences of leaving /sys/module/usbcore/parameters/old_scheme_first=Y for the long-term? Is there a better solution?

Thanks!

Edited October 3, 20205 yr by splerman