Problem with USB selective suspend in Windows 11

Question

Hi, I am using an FTDI 601 USB development board and I need to prevent the PC from putting it into selective suspend (it stops the internal FIFO clock). I've tried setting all the hubs to disable suspend and I used the Power Options in Control Panel to disable USB suspend. Unfortunately, the development board still enables selective suspend whenever it is connected to the USB, and I just cannot prevent this from happening. Is there a way to completely disable 'selective suspend'?

Thanks!
Terry

Answer 1

Hello,

First, I would recommend disabling the Power Management in the USB Root. For this you can access Device Manager in Windows, then finding the USB Root or Hubs in the category "Universal Serial Bus Controllers", then in their properties go to the "Power Management" tab and uncheck the "Allow the computer to turn off this device to save power". You can additionally check for the Development board in the HID or Other Devices to see if the driver also has enabled some sort of Power Management option.

Last but not least about the device itself you can modify this through the registry as the next steps:
-In Regedit, in the search bar, paste the following address: Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\USB.

-Find your device’s PID by right-clicking it in Device Manager and selecting Properties, then “Hardware IDs” in the “Details” tab.

-Find the device’s PID in the Registry Editor sidebar, then press Ctrl +F and search for SelectiveSuspendEnabled to check if there is already a registry entry under that name.

-If there isn’t, right-click in the sub-folder of “Device Parameters” and choose “New > DWORD (32-bit)”. Name it SelectiveSuspendEnabled.

-Double-click your “SelectiveSuspendEnabled” key and change the value data to one of the following:

1: Enable USB selective suspend
0: Disable USB selective suspend

Press “OK” when you’re done.

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