On Thu, 20 Feb 2020, Belisko Marek wrote: > Hi, > > I'm playing with functionfs and use configfs + functionfs + ffs-test > from kernel to test connection between my device and host. ffs-test > example provide 1 configuration with 1 interface and with 2 bulk > endpoints. > > I'm writing application which will write/read data to usb device but > can be accessed from other multiple application. I'm planning to write > kind of gatekeeper which will serialize data to endpoint and notify > reader about received data. > > I was thinking about other possibility to extend gadget to provide > more endpoints (like 2). I was able to extend ffs-test and also I can > send/receive data (using libusb) over original endpoints but not over > new created one (I've run 2 instances of same application which > basically create transfers for 2 different endpoints) but when running > second application I got this error: > > libusb: error [submit_bulk_transfer] submiturb failed error -1 errno=16 > libusb: error [submit_bulk_transfer] submiturb failed error -1 errno=16 Only one program at a time can claim an interface, and submitting an URB to an endpoint automatically claims the endpoint's interface. > I'm not USB expert but multiple endpoint should be possible (maybe I > need to put them to other interface?-> tried that also but got same > error as above with errno=2). Thanks for any pointers and advice. errno=16 and errno=2 are different errors, not the same error. Putting the endpoints in different interfaces should work; you probably have a bug somewhere in your code. Alan Stern
