I am working on a platform (Xilinx Zynq Ultrascale+), which is supposed to work as a pure USB Device (not dual-role). To get fast USB bulk transfers I wanted to have something similar like USBDEVFS_SUBMITURB/USBDEVFS_REAPURB, but for an USB Device. I now implement two new ioctls for FunctionFS: FUNCTIONFS_SUBMITBULKURB FUNCTIONFS_REAPBULKURB which provide simliar functionality. A similar functionality is already implemented via AIO. But: To use this API, your user space environment needs to know how to use these system calls. Additionally the semantics of the ioctls is slightly different: Usually you can only access a FunctionFS file if the FunctionFS is already bound to an UDC (USB Device Controller) and the USB Device is connected to a USB Host (which then enables the appropriate configuration and USB endpoints). These new ioctls behave different: You already can submit URBs before the Function is bound to an UDC and before the USB Device is connected. These "pending" URBs will be activated once the endpoints become active. When the endpoints become deactivated (either by a disconnect from the USB Host or by unbinding the UDC), active URBs are cancelled. A user space program will then get a notification, that the URBs have been cancelled and the status will indicate to the user space program, that the connection was lost. Via this mechanism a user space program can keep precise track, which URBs succeeded and which URBs failed. The final goal here is to be able to directly let user space provide data buffers (via mmap I guess), which are then transferred via USB; but this is the next step. I implemented test code to demonstrate how to use these new ioctls. Ingo Rohloff (2): usb: gadget: ffs: Implement user URBs for USB bulk endpoints usb: gadget: ffs: tools: test applications for user URBs. drivers/usb/gadget/function/f_fs.c | 478 ++++++++++++++++++ include/uapi/linux/usb/functionfs.h | 14 + .../device_app/usb_func_echo.c | 474 +++++++++++++++++ .../ffs-urb-example/device_app/usb_gadget_mk | 79 +++ .../ffs-urb-example/host_app/usb_test_echo.c | 370 ++++++++++++++ 5 files changed, 1415 insertions(+) create mode 100644 tools/usb/ffs-urb-example/device_app/usb_func_echo.c create mode 100644 tools/usb/ffs-urb-example/device_app/usb_gadget_mk create mode 100644 tools/usb/ffs-urb-example/host_app/usb_test_echo.c -- 2.17.1
