I have a composite USB device that emulates a sound card and a serial port. The sound card portion works as expected, however I am having trouble trying to communicate with the COM port of this device. The issue seems to be that the com port is not being assigned (or I don't understand how it is being assigned). Running dmesg yields the following info regarding this device when plugged into the port:
01 [ 55.328014] usb 8-2: new full-speed USB device number 2 using uhci_hcd 02 [ 55.497033] usb 8-2: New USB device found, idVendor=1fc9, idProduct=400f 03 [ 55.497038] usb 8-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3 04 [ 55.497042] usb 8-2: Product: TONE GENERATOR+CDC 05 [ 55.497045] usb 8-2: Manufacturer: CIE Engineering Inc Tgen4 06 [ 55.497048] usb 8-2: SerialNumber: 0001 07 [ 55.528800] usbcore: registered new interface driver snd-usb-audio 08 [ 55.529499] cdc_acm: probe of 8-2:1.2 failed with error -22 09 [ 55.529526] usbcore: registered new interface driver cdc_acm 10 [ 55.529529] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters
I’ve added ‘line numbers’ to the log above for reference.
Line 01:the new device being plugged in to USB bus 8 device 2.
Lines 02-06: various config info for the card
Line 07: recognition of the virtual ‘sound card’
Line 08 shows an error with the virtual com port (cdc_acm)
Line 09 shows the registration of a new virtual com port
Line 10 shows the ACM driver load.
The error message shown in line 8 is 'EINVAL' or an 'invalid argument', but lines 9 and 10 seem to indicate that a driver was 'registered'. The behavior I was hoping for was that a com port would be assigned @ ttyACM0 but that doesn't happen. Examining the com ports before and after the device's insertion shows no new tty* ports.
The OS is Ubuntu 14.04.5 LTS.