What USB PHY 2.0 driver?
An apparently missing USB PHY 2.0 driver error is known to come up with a type of inexpensive generic web camera. When this error presents itself the webcam is inoperable. Furthermore Windows Update cannot provide a driver. The error is displayed under Device Manager under Other Devices and associated with Hardware ID USB\VID_1224&PID_2A25&REV_0100. Aside from that though there is not much to go on even on the internet.
Given the description of the error one might be led to believe that one needs to find a driver USB PHY 2.0 driver from somewhere and install it. That is probably not the case. Going down that route is likely going to be a waste of time if the simple solution works. Because there is a simple fix to this problem. The quick fix is to make sure to install the webcam in a USB 3.0 port and not a USB 2.0 port.