[libhid-discuss] Using libhid with composit device

[Ali Asad]

Hi,

I have two somewhat related questions regarding libhid on Linux (Ubuntu).

1. What is the difference betweeen hid_force_open() and hid_open()?
I read from the documentation and code comments that "force" version attempts to unmount the device to take control away from Linux hiddev driver. Is this step necessary? I say this because it may be related to the my second questions.

2. Is is possible to unmount only the HID enumeration of a device and leave any additional enunmerations still mounted? In my case, I have a USB memory stick that enumerates as a USB composite device: a mass storage device, and an HID device. When I call hid_force_open(), the mass storage drives on this device disappear. I assume the unmount call in hid_force_open() does this.

So, is there a way for me to access the HID part of the device through libhid without unmounting the complete device, or have I reached a dead-end in terms of supporting this device on Linux.

Best regards, and thanks for your help,
--- Asad

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