Hello. I am trying to use configfs I/F of compsite gadget to add my additional EPs. The EPs (multiple) are simple IN and OUT pipes which I intend to write/read on peripheral (gadget) side user-mode application. I intend to use file read/write. As I look into the memos and driver source code, I think the below steps might work. (This is the first time I try configfs based gadget setting, and still looking into what it can do.) i) Add my function to my gadget definition mkdir functions/ffs.usb1 ln -s functions/ffs.usb1 configs/c.1 ii) Mount it as functionfs mkdir /dev/myffs1 mount usb1 /dev/myffs1 iii) Set descriptors, etc. Write necessary info into /dev/myffs1/ep0 (So that ffs thinks descriptors are ready.) iv) Bind echo controller-path > usb_gadget/g1/UDC Just as the step described as: https://wiki.tizen.org/USB/Linux_USB_Layers/Configfs_Composite_Gadget/Usage_eq._to_g_ffs.ko Now I have a fiew quetions. If you have immediate answers to these it may save my time and I greately appreciate. 1) Is this the proper way to do it? (The ffs function is designed so that it can add additional file i/o EPs to existing gadget?) 2) The step ii) and iii) are still needed? i.e. Even if I use configfs, this part is using functionfs and also I need to make myself data that can be understood by ffs ep0. 3) The /ev/myffs1/ep0 is shared with EP0 that the gadtet device defines? I think the device will define EP0 and the host will ready/write data from/to it, after it is available on USB. What is the relationship beteen the data read/write on /dev/myffs1/ep0 (by user-mode applciation) and data read/write on USB EP0? 4) At step iii), I need to encode descriptor, etc. info and write to /dev/myffs/ep0. Any convenient tool to do it (encoding), or I just should write tiny util for that? Thank you for your cooperation.
