How to prevent a usb device from entering low power state?

NTDEV
1

Hi
I am trying to create a emulated usb camera, I found that the driver will soon enter low power state,
Which I can not accept UVC command then
So how can I prevent the driver from entering the low power state?
Will WdfDeviceAssignS0IdleSettings works for this purpose?
Thanks in advance

2

If you do that, you will prevent the whole system from going to sleep. I don’t see how it will help for your emulator driver to call that API; what’s important is usbvideo.sys, and it’s going to follow its rules. You do have a very small amount of control over the power behavior in your USB descriptors, but it’s not enough.

Still, when an app sends a command, that should cause the driver to go back to D0. Are you seeing them get blocked?

I have told you many times that this is not the right way to support a non-USB video device. You will continue to have pain like this.

3

Well, you can NOT specify an idle timeout in your S0 idle settings.

Or just call WdfStopIdle.

Peter