2.6.28 changes in-kernel name for UVC device ?

From: Ionut Leonte
Date: Tue Jan 20 2009 - 06:49:53 EST

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I have a Dell laptop with an integrated webcam which works with the 'uvcvideo'
module. For kernel versions 2.6.27 and below the following udev rule:

KERNEL=="video[0-9]*", NAME="v4l/video%n", SYMLINK+="%k", GROUP="video"

would create '/dev/video0' as a link to '/dev/v4l/video0'. When switching to
2.6.28 the rule creates '/dev/video1394-0' instead. Obviously most user-space
apps were quite surprised by this (as was I).

Is this change intended or is it the accidental result of some modification ?

(attached 'lsusb' information for the device)

Bus 002 Device 003: ID 05a9:2640 OmniVision Technologies, Inc.
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 ?
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 64
idVendor 0x05a9 OmniVision Technologies, Inc.
idProduct 0x2640
bcdDevice 1.00
iManufacturer 1 OmniVision Technologies, Inc. -2640-07.07.20.3
iProduct 2 Laptop Integrated Webcam
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 705
bNumInterfaces 2
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 500mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 14 Video
bFunctionSubClass 3 Video Interface Collection
bFunctionProtocol 0
iFunction 2 Laptop Integrated Webcam
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 1 Video Control
bInterfaceProtocol 0
iInterface 2 Laptop Integrated Webcam
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 109
dwClockFrequency 30.000000MHz
bInCollection 1
baInterfaceNr( 0) 1
VideoControl Interface Descriptor:
bLength 17
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 1
wTerminalType 0x0201 Camera Sensor
bAssocTerminal 0
iTerminal 0
wObjectiveFocalLengthMin 0
wObjectiveFocalLengthMax 0
wOcularFocalLength 0
bControlSize 2
bmControls 0x00000a00
Zoom (Absolute)
PanTilt (Absolute)
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 3
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 5
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 0
bControlSize 2
bmControls 0x0000557f
Brightness
Contrast
Hue
Saturation
Sharpness
Gamma
White Balance Temperature
Backlight Compensation
Power Line Frequency
White Balance Temperature, Auto
Digital Multiplier
iProcessing 0
bmVideoStandards 0x1a
NTSC - 525/60
SECAM - 625/50
NTSC - 625/50
VideoControl Interface Descriptor:
bLength 26
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 7
guidExtensionCode {8a0f88dd-ba1c-5449-8a25-f7875967f0f7}
bNumControl 1
bNrPins 1
baSourceID( 0) 1
bControlSize 1
bmControls( 0) 0x01
iExtension 0
VideoControl Interface Descriptor:
bLength 26
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 6
guidExtensionCode {08f74a8e-ab51-2546-a2a2-31aab38e59da}
bNumControl 1
bNrPins 1
baSourceID( 0) 5
bControlSize 1
bmControls( 0) 0x01
iExtension 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 16
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 15
bDescriptorType 36
bDescriptorSubtype 1 (INPUT_HEADER)
bNumFormats 2
wTotalLength 485
bEndPointAddress 129
bmInfo 0
bTerminalLink 3
bStillCaptureMethod 0
bTriggerSupport 0
bTriggerUsage 0
bControlSize 1
bmaControls( 0) 11
bmaControls( 1) 11
VideoStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 6 (FORMAT_MJPEG)
bFormatIndex 1
bNumFrameDescriptors 9
bFlags 1
Fixed-size samples: Yes
bDefaultFrameIndex 1
bAspectRatioX 0
bAspectRatioY 0
bmInterlaceFlags 0x00
Interlaced stream or variable: No
Fields per frame: 1 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 147456000
dwMaxBitRate 147456000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 160
wHeight 120
dwMinBitRate 9216000
dwMaxBitRate 9216000
dwMaxVideoFrameBufferSize 38400
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 3
bmCapabilities 0x00
Still image unsupported
wWidth 176
wHeight 144
dwMinBitRate 12165120
dwMaxBitRate 12165120
dwMaxVideoFrameBufferSize 50688
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 4
bmCapabilities 0x00
Still image unsupported
wWidth 320
wHeight 240
dwMinBitRate 36864000
dwMaxBitRate 36864000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 5
bmCapabilities 0x00
Still image unsupported
wWidth 352
wHeight 288
dwMinBitRate 48660480
dwMaxBitRate 48660480
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 6
bmCapabilities 0x00
Still image unsupported
wWidth 800
wHeight 600
dwMinBitRate 230400000
dwMaxBitRate 230400000
dwMaxVideoFrameBufferSize 960000
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 7
bmCapabilities 0x00
Still image unsupported
wWidth 1024
wHeight 768
dwMinBitRate 94371840
dwMaxBitRate 94371840
dwMaxVideoFrameBufferSize 1572864
dwDefaultFrameInterval 1000000
bFrameIntervalType 1
dwFrameInterval( 0) 1000000
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 8
bmCapabilities 0x00
Still image unsupported
wWidth 1280
wHeight 1024
dwMinBitRate 157286400
dwMaxBitRate 157286400
dwMaxVideoFrameBufferSize 2621440
dwDefaultFrameInterval 1000000
bFrameIntervalType 1
dwFrameInterval( 0) 1000000
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 7 (FRAME_MJPEG)
bFrameIndex 9
bmCapabilities 0x00
Still image unsupported
wWidth 1600
wHeight 1200
dwMinBitRate 230400000
dwMaxBitRate 230400000
dwMaxVideoFrameBufferSize 3840000
dwDefaultFrameInterval 1000000
bFrameIntervalType 1
dwFrameInterval( 0) 1000000
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))
VideoStreaming Interface Descriptor:
bLength 27
bDescriptorType 36
bDescriptorSubtype 4 (FORMAT_UNCOMPRESSED)
bFormatIndex 2
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: 1 fields
Field 1 first: No
Field pattern: Field 1 only
bCopyProtect 0
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 1
bmCapabilities 0x00
Still image unsupported
wWidth 640
wHeight 480
dwMinBitRate 147456000
dwMaxBitRate 147456000
dwMaxVideoFrameBufferSize 614400
dwDefaultFrameInterval 1000000
bFrameIntervalType 1
dwFrameInterval( 0) 1000000
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 2
bmCapabilities 0x00
Still image unsupported
wWidth 160
wHeight 120
dwMinBitRate 9216000
dwMaxBitRate 9216000
dwMaxVideoFrameBufferSize 38400
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 3
bmCapabilities 0x00
Still image unsupported
wWidth 176
wHeight 144
dwMinBitRate 12165120
dwMaxBitRate 12165120
dwMaxVideoFrameBufferSize 50688
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 4
bmCapabilities 0x00
Still image unsupported
wWidth 320
wHeight 240
dwMinBitRate 36864000
dwMaxBitRate 36864000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
VideoStreaming Interface Descriptor:
bLength 30
bDescriptorType 36
bDescriptorSubtype 5 (FRAME_UNCOMPRESSED)
bFrameIndex 5
bmCapabilities 0x00
Still image unsupported
wWidth 352
wHeight 288
dwMinBitRate 48660480
dwMaxBitRate 48660480
dwMaxVideoFrameBufferSize 202752
dwDefaultFrameInterval 333333
bFrameIntervalType 1
dwFrameInterval( 0) 333333
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 0x03fc 1x 1020 bytes
bInterval 1
** UNRECOGNIZED: 30 ff 42 49 53 54 00 01 08 01 10 00 00 00 00 00 d1 03 f4 01 d2 04 f4 01 d3 05 f4 01 d4 06 f4 01 d5 07 f4 01 d6 08 f4 01 d7 09 f4 01 d8 0a f4 01
Device Qualifier (for other device speed):
bLength 10
bDescriptorType 6
bcdUSB 2.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 ?
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 8
bNumConfigurations 1
Device Status: 0x0000
(Bus Powered)

Next message: Ingo Molnar: "Re: 2.6.29-rc1 does not resume on Lenove T61"
Previous message: Christoph Hellwig: "Re: [XFS] 2.6.29-rc2: XFS internal error XFS_WANT_CORRUPTED_GOTO"
Next in thread: Kay Sievers: "Re: 2.6.28 changes in-kernel name for UVC device ?"
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