Linux USB driver probe not called if device already plugged

Question

If I use a modified usb skeleton driver on Linux and I insmod the module with the USB device already plugged in, the probe function doesn't get called. I need to unplug and replug the device in order for the driver to be activated. This is not the case for e.g. the serial drivers, I made some tests. Is there a reason for this? How do I get the probe function to get called?

Answer 1

Some software from us was opening the device from /proc/bus/usb and the device was claimed by the usbfs driver, so the new driver couldn't claim the device.