On Thu, 20 Feb 2020, Belisko Marek wrote: > 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. Did you check the kernel log on the host after plugging in the USB cable? There ought to be a complaint about multiple interface descriptors for interface 0 altsetting 0. > Also one thing I noticed is that bNumInterfaces still shows 1 (even I > have 2 interface descriptors) and not 2 as I would expect. Yes, I noticed that too. In addition, the second interface has bInterfaceNumber set to 0, not 1. > Is there something I'm doing wrong or maybe it can be bug in ffs code? I don't know the ffs code. However I guess it's probably something you're doing wrong. Maybe the incorrect bInterfaceNumber is the cause. > Is there any drawback of using multiple endpoints in overall transfer speed? No. The available bandwidth gets shared between them as needed. Alan Stern
