Add a DetachKernelDriver wrapper

[Dadoum]

Allows the library user to detach kernel drivers only for specific interfaces, which is useful when handling only a part of a more complex device.

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[zagrodzki]

I think this is generally fine, but I'm curious about the use case. Please update the PR description.

gofmt has something to say about your changes; see the test failures.

[Dadoum]

The library already has a function to detach all drivers from a device upon opening it, but sometimes you might only want to detach the driver from only one interface, like in my case, using go-ncm on one specific interface of the phone but still leave the previous usbmuxer do its job managing the other ones.

[zagrodzki]

I think this should be on the Configuration rather than the Device? Once a Device is opened, you would need to select a configuration before you know what interfaces are available.

[zagrodzki]

I'm wondering if there could be a universal approach to detaching kernel drivers. Right now the API is mixing two approaches:

• autodetach on the device, which is really acting when a configuration is selected. Detaches when user tries to access the resource.
• (proposed) detach a specific interface (in a specific config of a specific device). User needs to explicitly detach.

And the implementation is also inconsistent, since calling Device.SetAutoDetach affects two things:

• detaches all interfaces when a config is selected
• calls libusb_set_auto_detach_kernel_driver, which auto-detaches when a specific interface is claimed.

It would be nice to have a consistent approach. I would lean towards disabling autodetach and preferring explicit DetachKernelDriver(int) and DetachKernelDriverAll() on the configuration.

An alternative would be to add Configuration.SetAutoDetach(), which would auto-detach on claimed interface, like Device.SetAutoDetach() auto-detaches on all interfaces of a configuration.

Or both. I don't know. Calling @stapelberg for a gut feeling check.

[stapelberg]

Or both. I don't know. Calling @stapelberg for a gut feeling check.

It’s been years since I last worked with USB APIs 😅

I don’t think my gut tells me anything on these questions, sorry.