[linux-uvc-devel] USB3 UVC Multi-camera device
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[linux-uvc-devel] USB3 UVC Multi-camera device
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From: Brian K. <sas...@gm...> - 2017-10-11 17:30:03
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Hi,
I'm currently developing a USB3 UVC peripheral which will feature 2 cameras as 2 discrete Video Interface Collections. I haven’t seen any similar products on the market, so in order to de-risk this effort I have started with a Cypress dev kit and I'm modifying their example project which loops a 2 frame video as “single camera” UVC compliant device. The initial demo project works fine, but with my firmware modifications I am encountering a handful of issues with uvcvideo on my Linux test machine (Ubuntu 17.04 / 4.10.0-35-generic).
The enumeration process and USB descriptors for my modified project appear to be fine when inspected with both my USB analyzer (Beagle USB 5000) and lsusb. I see both /dev/video0 and /dev/video1 but I run into issues once I try and access the streams (with VLC, gucvview, and the QTV4L2 test utility). All apps report variations of the error “no video device found”.
Digging into this a bit more, it appears that the host is not sending a GetDeviceStatus and GetInterfaceStatus when the feeds are accessed by the Host apps like I see with the single camera demo. I have turned on the uvcvideo trace and noticed the following peculiarities with the dmesg log.
During enumeration I get a dmesg error regarding the second camera and dbugfs. The exact error is “uvcvideo: Unable to create debugfs busnum-devnum directory.” This error obviously occurs because the busnum and devnum are the same for the 2nd camera, and debugfs was already created for the first camera.
The uvcvideo sequence is different between the two different firmware builds at the end of enumeration. With the single camera version of firmware I see the following sequence in dmesg:
[14332.280577] uvcvideo: UVC device initialized.
[14332.292304] uvcvideo: uvc_v4l2_open
[14332.292360] uvcvideo: uvc_v4l2_release
[14334.293725] uvcvideo: Suspending interface 1
[14334.293726] uvcvideo: Suspending interface 0
However, with the 2 camera firmware I see:
[14580.171459] uvcvideo: UVC device initialized.
[14580.183685] uvcvideo: uvc_v4l2_open
[14580.184600] uvcvideo: uvc_v4l2_open
[14582.186638] uvcvideo: Suspending interface 3
[14582.186639] uvcvideo: Suspending interface 2
[14582.186640] uvcvideo: Suspending interface 1
[14582.186641] uvcvideo: Suspending interface 0
Note that the device is never released.
Based on these findings, it looks like I’ll need to dive into the Linux uvcvideo source but I don’t have any experience in this source. Is there anyone on this list that might be able to tell me if I have overlooked some aspect of the UVC spec? Is it possible that I’m encountering issues that were overlooked since no multi-camera multi-feed devices exist? I know stereoscopic cameras do exist, but from what I have seen those devices have 1 VIC and only 1 stereo stream.
Thanks in advance,
Brian
BTW, for reference the lsusb details are shown below:
Bus 002 Device 006: ID 04b4:4722 Cypress Semiconductor Corp.
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 3.00
bDeviceClass 239 Miscellaneous Device
bDeviceSubClass 2 ?
bDeviceProtocol 1 Interface Association
bMaxPacketSize0 9
idVendor 0x04b4 Cypress Semiconductor Corp.
idProduct 0x4722
bcdDevice 0.00
iManufacturer 1 Cypress
iProduct 2 FX3
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 395
bNumInterfaces 4
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 100mA
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 0
bInterfaceCount 2
bFunctionClass 14 Video
bFunctionSubClass 3 Video Interface Collection
bFunctionProtocol 0
iFunction 3 CAM1
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 1 Video Control
bInterfaceProtocol 1
iInterface 3 CAM1
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 81
dwClockFrequency 0.000000MHz
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 3 CAM1
wObjectiveFocalLengthMin 0
wObjectiveFocalLengthMax 0
wOcularFocalLength 0
bControlSize 3
bmControls 0x00000000
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 5 (PROCESSING_UNIT)
bUnitID 2
bSourceID 1
wMaxMultiplier 0
bControlSize 3
bmControls 0x00000000
iProcessing 0
bmVideoStandards 0x 0
VideoControl Interface Descriptor:
bLength 28
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 3
guidExtensionCode {ffffffff-ffff-ffff-ffff-ffffffffffff}
bNumControl 0
bNrPins 1
baSourceID( 0) 2
bControlSize 3
bmControls( 0) 0x00
bmControls( 1) 0x00
bmControls( 2) 0x00
iExtension 0
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 4
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 3
iTerminal 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x4000 1x 0 bytes
bInterval 1
bMaxBurst 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 1
iInterface 0
VideoStreaming Interface Descriptor:
bLength 14
bDescriptorType 36
bDescriptorSubtype 1 (INPUT_HEADER)
bNumFormats 1
wTotalLength 25
bEndPointAddress 129
bmInfo 0
bTerminalLink 4
bStillCaptureMethod 1
bTriggerSupport 1
bTriggerUsage 0
bControlSize 1
bmaControls( 0) 11
VideoStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 6 (FORMAT_MJPEG)
bFormatIndex 1
bNumFrameDescriptors 1
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 6144000
dwMaxBitRate 6144000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 666666
bFrameIntervalType 1
dwFrameInterval( 0) 666666
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x4000 1x 0 bytes
bInterval 0
bMaxBurst 7
Interface Association:
bLength 8
bDescriptorType 11
bFirstInterface 2
bInterfaceCount 2
bFunctionClass 14 Video
bFunctionSubClass 3 Video Interface Collection
bFunctionProtocol 0
iFunction 4 CAM2
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 2
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 1 Video Control
bInterfaceProtocol 1
iInterface 4 CAM2
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 1 (HEADER)
bcdUVC 1.00
wTotalLength 81
dwClockFrequency 0.000000MHz
bInCollection 1
baInterfaceNr( 0) 3
VideoControl Interface Descriptor:
bLength 18
bDescriptorType 36
bDescriptorSubtype 2 (INPUT_TERMINAL)
bTerminalID 5
wTerminalType 0x0201 Camera Sensor
bAssocTerminal 0
iTerminal 4 CAM2
wObjectiveFocalLengthMin 0
wObjectiveFocalLengthMax 0
wOcularFocalLength 0
bControlSize 3
bmControls 0x00000000
VideoControl Interface Descriptor:
bLength 13
bDescriptorType 36
bDescriptorSubtype 5 (PROCESSING_UNIT)
bUnitID 6
bSourceID 5
wMaxMultiplier 0
bControlSize 3
bmControls 0x00000000
iProcessing 0
bmVideoStandards 0x 0
VideoControl Interface Descriptor:
bLength 28
bDescriptorType 36
bDescriptorSubtype 6 (EXTENSION_UNIT)
bUnitID 7
guidExtensionCode {ffffffff-ffff-ffff-ffff-ffffffffffff}
bNumControl 0
bNrPins 1
baSourceID( 0) 6
bControlSize 3
bmControls( 0) 0x00
bmControls( 1) 0x00
bmControls( 2) 0x00
iExtension 0
VideoControl Interface Descriptor:
bLength 9
bDescriptorType 36
bDescriptorSubtype 3 (OUTPUT_TERMINAL)
bTerminalID 8
wTerminalType 0x0101 USB Streaming
bAssocTerminal 0
bSourceID 7
iTerminal 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x84 EP 4 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x4000 1x 0 bytes
bInterval 1
bMaxBurst 0
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 3
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 14 Video
bInterfaceSubClass 2 Video Streaming
bInterfaceProtocol 1
iInterface 0
VideoStreaming Interface Descriptor:
bLength 14
bDescriptorType 36
bDescriptorSubtype 1 (INPUT_HEADER)
bNumFormats 1
wTotalLength 25
bEndPointAddress 131
bmInfo 0
bTerminalLink 8
bStillCaptureMethod 1
bTriggerSupport 1
bTriggerUsage 0
bControlSize 1
bmaControls( 0) 11
VideoStreaming Interface Descriptor:
bLength 11
bDescriptorType 36
bDescriptorSubtype 6 (FORMAT_MJPEG)
bFormatIndex 1
bNumFrameDescriptors 1
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 6144000
dwMaxBitRate 6144000
dwMaxVideoFrameBufferSize 153600
dwDefaultFrameInterval 666666
bFrameIntervalType 1
dwFrameInterval( 0) 666666
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x4000 1x 0 bytes
bInterval 0
bMaxBurst 7
Binary Object Store Descriptor:
bLength 5
bDescriptorType 15
wTotalLength 15
bNumDeviceCaps 1
SuperSpeed USB Device Capability:
bLength 10
bDescriptorType 16
bDevCapabilityType 3
bmAttributes 0x00
wSpeedsSupported 0x0008
Device can operate at SuperSpeed (5Gbps)
bFunctionalitySupport 3
Lowest fully-functional device speed is SuperSpeed (5Gbps)
bU1DevExitLat 0 micro seconds
bU2DevExitLat 0 micro seconds
Device Status: 0x0000
(Bus Powered)
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