I just obtained a new (special-purpose) webcam, and it doesn't seem to work at all. On kernel torvals/linux.git next branch, it doesn't even really connect, on 3.13 (which I'm running on my laptop) I get errors like this: xhci_hcd 0000:00:14.0: ERROR Transfer event TRB DMA ptr not part of current TD when running uvccapture. When running e.g. cheese or the like, the screen stays blank. uvccapture also reports: ioctl querycontrol error 22 and then the kernel message repeats forever, while I can't even exit uvccapture unless I kill it hard, at which point I get xhci_hcd 0000:00:14.0: Signal while waiting for configure endpoint command usb 1-3.4.4.3: Not enough bandwidth for altsetting 0 from the kernel. The device really is detected as UVC, of course: [ 3423.299311] usb 1-3.4.4.3: new high-speed USB device number 12 using xhci_hcd [ 3423.426280] usb 1-3.4.4.3: New USB device found, idVendor=058f, idProduct=5608 [ 3423.426286] usb 1-3.4.4.3: New USB device strings: Mfr=3, Product=1, SerialNumber=0 [ 3423.426290] usb 1-3.4.4.3: Product: USB 2.0 PC Camera [ 3423.426293] usb 1-3.4.4.3: Manufacturer: Alcor Micro, Corp. [ 3423.432137] uvcvideo: Found UVC 1.00 device USB 2.0 PC Camera (058f:5608) [ 3423.435383] input: USB 2.0 PC Camera as /devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.4/1-3.4.4/1-3.4.4.3/1-3.4.4.3:1.0/input/input36 (see also full lsusb below) I see a device from the same manufacturer has a kernel driver as a vendor device but actually being UVC, but this one reports being UVC and doesn't really work. Any thoughts? Just to rule out hardware defects I connected it to my windows 7 work machine and it works fine without even installing a driver. I can arrange remote access to the device (maybe as a VM to be able to experiment with the kernel more easily?) if anyone wants it. johannes lsusb: Bus 001 Device 012: ID 058f:5608 Alcor Micro Corp. Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 239 Miscellaneous Device bDeviceSubClass 2 ? bDeviceProtocol 1 Interface Association bMaxPacketSize0 64 idVendor 0x058f Alcor Micro Corp. idProduct 0x5608 bcdDevice 0.03 iManufacturer 3 Alcor Micro, Corp. iProduct 1 USB 2.0 PC Camera iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 407 bNumInterfaces 2 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 200mA Interface Association: bLength 8 bDescriptorType 11 bFirstInterface 0 bInterfaceCount 2 bFunctionClass 14 Video bFunctionSubClass 3 Video Interface Collection bFunctionProtocol 0 iFunction 1 USB 2.0 PC Camera Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 1 Video Control bInterfaceProtocol 0 iInterface 1 USB 2.0 PC Camera VideoControl Interface Descriptor: bLength 13 bDescriptorType 36 bDescriptorSubtype 1 (HEADER) bcdUVC 1.00 wTotalLength 85 dwClockFrequency 30.000000MHz bInCollection 1 baInterfaceNr( 0) 1 VideoControl Interface Descriptor: bLength 18 bDescriptorType 36 bDescriptorSubtype 2 (INPUT_TERMINAL) bTerminalID 1 wTerminalType 0x0201 Camera Sensor bAssocTerminal 0 iTerminal 0 wObjectiveFocalLengthMin 0 wObjectiveFocalLengthMax 0 wOcularFocalLength 0 bControlSize 3 bmControls 0x00000000 VideoControl Interface Descriptor: bLength 9 bDescriptorType 36 bDescriptorSubtype 3 (OUTPUT_TERMINAL) bTerminalID 3 wTerminalType 0x0101 USB Streaming bAssocTerminal 0 bSourceID 6 iTerminal 0 VideoControl Interface Descriptor: bLength 7 bDescriptorType 36 bDescriptorSubtype 4 (SELECTOR_UNIT) bUnitID 4 bNrInPins 1 baSource( 0) 1 iSelector 0 VideoControl Interface Descriptor: bLength 11 bDescriptorType 36 bDescriptorSubtype 5 (PROCESSING_UNIT) Warning: Descriptor too short bUnitID 5 bSourceID 4 wMaxMultiplier 32208 bControlSize 2 bmControls 0x0000157f Brightness Contrast Hue Saturation Sharpness Gamma White Balance Temperature Backlight Compensation Power Line Frequency White Balance Temperature, Auto iProcessing 0 bmVideoStandards 0x1b None NTSC - 525/60 SECAM - 625/50 NTSC - 625/50 VideoControl Interface Descriptor: bLength 27 bDescriptorType 36 bDescriptorSubtype 6 (EXTENSION_UNIT) bUnitID 6 guidExtensionCode {564c97a7-7ea7-904b-8cbf-1c71ec303000} bNumControl 16 bNrPins 1 baSourceID( 0) 5 bControlSize 2 bmControls( 0) 0xff bmControls( 1) 0xff iExtension 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0010 1x 16 bytes bInterval 15 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 0 bNumEndpoints 0 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 VideoStreaming Interface Descriptor: bLength 14 bDescriptorType 36 bDescriptorSubtype 1 (INPUT_HEADER) bNumFormats 1 wTotalLength 227 bEndPointAddress 129 bmInfo 0 bTerminalLink 3 bStillCaptureMethod 2 bTriggerSupport 0 bTriggerUsage 0 bControlSize 1 bmaControls( 0) 27 VideoStreaming Interface Descriptor: bLength 27 bDescriptorType 36 bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED) bFormatIndex 1 bNumFrameDescriptors 5 guidFormat {59555932-0000-1000-8000-00aa00389b71} bBitsPerPixel 16 bDefaultFrameIndex 1 bAspectRatioX 0 bAspectRatioY 0 bmInterlaceFlags 0x00 Interlaced stream or variable: No Fields per frame: 2 fields Field 1 first: No Field pattern: Field 1 only bCopyProtect 0 VideoStreaming Interface Descriptor: bLength 34 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 1 bmCapabilities 0x00 Still image unsupported wWidth 640 wHeight 480 dwMinBitRate 73728000 dwMaxBitRate 147456000 dwMaxVideoFrameBufferSize 614400 dwDefaultFrameInterval 333332 bFrameIntervalType 2 dwFrameInterval( 0) 333332 dwFrameInterval( 1) 666666 VideoStreaming Interface Descriptor: bLength 34 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 2 bmCapabilities 0x00 Still image unsupported wWidth 320 wHeight 240 dwMinBitRate 18432000 dwMaxBitRate 36864000 dwMaxVideoFrameBufferSize 153600 dwDefaultFrameInterval 333332 bFrameIntervalType 2 dwFrameInterval( 0) 333332 dwFrameInterval( 1) 666666 VideoStreaming Interface Descriptor: bLength 34 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 3 bmCapabilities 0x00 Still image unsupported wWidth 160 wHeight 120 dwMinBitRate 4608000 dwMaxBitRate 9216000 dwMaxVideoFrameBufferSize 38400 dwDefaultFrameInterval 333332 bFrameIntervalType 2 dwFrameInterval( 0) 333332 dwFrameInterval( 1) 666666 VideoStreaming Interface Descriptor: bLength 34 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 4 bmCapabilities 0x00 Still image unsupported wWidth 352 wHeight 288 dwMinBitRate 24330240 dwMaxBitRate 48660480 dwMaxVideoFrameBufferSize 202752 dwDefaultFrameInterval 333332 bFrameIntervalType 2 dwFrameInterval( 0) 333332 dwFrameInterval( 1) 666666 VideoStreaming Interface Descriptor: bLength 34 bDescriptorType 36 bDescriptorSubtype 5 (FRAME_UNCOMPRESSED) bFrameIndex 5 bmCapabilities 0x00 Still image unsupported wWidth 176 wHeight 144 dwMinBitRate 6082560 dwMaxBitRate 12165120 dwMaxVideoFrameBufferSize 50688 dwDefaultFrameInterval 333332 bFrameIntervalType 2 dwFrameInterval( 0) 333332 dwFrameInterval( 1) 666666 VideoStreaming Interface Descriptor: bLength 10 bDescriptorType 36 bDescriptorSubtype 3 (STILL_IMAGE_FRAME) bEndpointAddress 0 bNumImageSizePatterns 1 wWidth( 0) 640 wHeight( 0) 480 bNumCompressionPatterns 1 VideoStreaming Interface Descriptor: bLength 6 bDescriptorType 36 bDescriptorSubtype 13 (COLORFORMAT) bColorPrimaries 1 (BT.709,sRGB) bTransferCharacteristics 1 (BT.709) bMatrixCoefficients 4 (SMPTE 170M (BT.601)) Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 1 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x1400 3x 1024 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 2 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x1400 3x 1024 bytes bInterval 1 Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 1 bAlternateSetting 3 bNumEndpoints 1 bInterfaceClass 14 Video bInterfaceSubClass 2 Video Streaming bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 5 Transfer Type Isochronous Synch Type Asynchronous Usage Type Data wMaxPacketSize 0x1400 3x 1024 bytes bInterval 1 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 239 Miscellaneous Device bDeviceSubClass 2 ? bDeviceProtocol 1 Interface Association bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html