hi Alan, On Thu, Feb 20, 2020 at 4:26 PM Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > 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. To clarify it a bit. I have test program which basically asynchronously sends buffer to bulk endpoint. Then as said if start second program I got errno=16 which means busy as other program already occupy endpoint so this is clear. But when extend ffs-test in this way https://pastebin.com/xymtDuJj using lsusb I can see: Bus 001 Device 010: ID 1d6b:0104 Linux Foundation Multifunction Composite Gadget Couldn't open device, some information will be missing Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0104 Multifunction Composite Gadget bcdDevice 4.12 iManufacturer 1 iProduct 2 iSerial 3 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 4 bmAttributes 0x80 (Bus Powered) MaxPower 2mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 5 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 5 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x02 EP 2 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 1 When use same program as before but writing to EP 2 OUT I got error 2. Also one thing I noticed is that bNumInterfaces still shows 1 (even I have 2 interface descriptors) and not 2 as I would expect. Is there something I'm doing wrong or maybe it can be bug in ffs code? Is there any drawback of using multiple endpoints in overall transfer speed? Thanks and BR, > > Alan Stern > marek
