Documentation/usb/functionfs.rst

9 that kernel level composite functions provide when they are added to
12 This in particular means that the composite initialisation functions
13 may not be in init section (ie. may not use the __init tag).
22 them as needed also handling situation when numbers differ in
35 What I also want to mention is that the FunctionFS is designed in such
36 a way that it is possible to mount it several times so in the end
37 a gadget could use several FunctionFS functions. The idea is that
45   $ insmod g_ffs.ko idVendor=<ID> iSerialNumber=<string> functions=mtp,hid
46   $ mkdir /dev/ffs-mtp && mount -t functionfs mtp /dev/ffs-mtp
47   $ ( cd /dev/ffs-mtp && mtp-daemon ) &
48   $ mkdir /dev/ffs-hid && mount -t functionfs hid /dev/ffs-hid
49   $ ( cd /dev/ffs-hid && hid-daemon ) &
51 On kernel level the gadget checks ffs_data->dev_name to identify
54 If no "functions" module parameters is supplied, the driver accepts
57 When "functions" module parameter is supplied, only functions
58 with listed names are accepted. In particular, if the "functions"
59 parameter's value is just a one-element list, then the behaviour
60 is similar to when there is no "functions" at all; however,
64 filesystems have been mounted and USB descriptors of all functions