Documentation/usb/functionfs.rst

8 From kernel point of view it is just a composite function with some
22 simply provide descriptors such as if the function was the
28 For more information about FunctionFS descriptors see :doc:`functionfs-desc`
38 When all files are closed the function disables itself.
51   $ mkdir /dev/ffs-mtp && mount -t functionfs mtp /dev/ffs-mtp
52   $ ( cd /dev/ffs-mtp && mtp-daemon ) &
53   $ mkdir /dev/ffs-hid && mount -t functionfs hid /dev/ffs-hid
54   $ ( cd /dev/ffs-hid && hid-daemon ) &
56 On kernel level the gadget checks ffs_data->dev_name to identify
60 just one function with any name.
64 parameter's value is just a one-element list, then the behaviour
66 only a function with the specified name is accepted.
68 The gadget is registered only after all the declared function
72 Conversely, the gadget is unregistered after the first USB function
83 objects between several interfaces, allowing it to transfer data in a
84 zero-copy fashion, for instance between IIO and the USB stack.
101     Enqueue the previously attached DMABUF to the transfer queue.
103     the size in bytes to transfer (which should generally correspond to