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I am writing an Usb driver and I have an issue. When I insmod the driver with the device already plugged in before hand, the probe function is not called. It is only called after I disconnect the device and plug it again. I want to make it so that it works when I start my pc with the device already plugged in.

Could someone please help me?

Laur Ivan
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jacob
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  • There is a difference between plugging the device and then loading the driver after the kernel has booted "and" loading the driver at boot time with the device already plugged in. Does it not work for both of these cases ? AFAIK it won't work if you load the module after plugging in the device. – Bandan Jun 17 '10 at 19:55

3 Answers3

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This can be solved by writing a proper udev rule for your device. Look for examples at /etc/udev/rules.d/

Anton Chikin
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From Documentation/driver-model/binding.txt:

When a new device is added, the bus's list of drivers is iterated over to find one that supports it. In order to determine that, the device ID of the device must match one of the device IDs that the driver supports. The format and semantics for comparing IDs is bus-specific.

From the same source:

The process is almost identical for when a new driver is added. The bus's list of devices is iterated over to find a match. Devices that already have a driver are skipped. All the devices are iterated over, to bind as many devices as possible to the driver.

So it looks like you have a problem in the ID matching, that is in your case specific to the USB bus, see the usb_device_match function in drivers/usb/core/driver.c.

Or it may be that your device already is bound to a device that is unloaded when the device is unplugged (you can check that by controlling if there is a symlink to a driver in the corresponding /sys/bus/usb/xxxxx directory)

Longfield
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"Or it may be that your device already is bound to a device that is unloaded when the device is unplugged (you can check that by controlling if there is a symlink to a driver in the corresponding /sys/bus/usb/xxxxx directory)"

And if there is a symlink?

pvinis
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