Re: [linux-uvc-devel] 04f2:b2db is supported, with non-functional second video device

[Kieran B. <kie...@id...>]

Hi Kevin,

On 20/09/2020 18:06, Kevin Locke wrote:
> Hi all,
> 
> The ThinkPad T430 includes a "Chicony Electronics Co., Ltd." "Integrated
> Camera" (04f2:b2db).  The camera works well with uvcvideo, but does not
> currently appear on the Supported Devices list.[1]  There are two,
> possibly related, oddities worth mentioning:

Camera's that follow the standard don't always need to be listed explicitly.

I'm glad it works for you.


> First, there are a few warnings printed when uvcvideo is loaded:
> 
> uvcvideo: Found UVC 1.00 device Integrated Camera (04f2:b2db)
> uvcvideo 3-1.6:1.0: Entity type for entity Extension 4 was not initialized!
> uvcvideo 3-1.6:1.0: Entity type for entity Extension 3 was not initialized!
> uvcvideo 3-1.6:1.0: Entity type for entity Processing 2 was not initialized!
> uvcvideo 3-1.6:1.0: Entity type for entity Camera 1 was not initialized!
> 
> Second, uvcvideo creates two video devices (video0 and video1):
> 
> $ readlink /sys/class/video4linux/video*
> ../../devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.6/3-1.6:1.0/video4linux/video0
> ../../devices/pci0000:00/0000:00:1a.0/usb3/3-1/3-1.6/3-1.6:1.0/video4linux/video1
> 
> `mpv /dev/video0` works well.  `mpv /dev/video1` fails with:
> 
> [ffmpeg/demuxer] video4linux2,v4l2: ioctl(VIDIOC_G_INPUT): Inappropriate ioctl for device
> 
> `v4l-info /dev/video1` shows:
> 
> ### v4l2 device info [/dev/video1] ###
> general info
>     VIDIOC_QUERYCAP
> 	driver                  : "uvcvideo"
> 	card                    : "Integrated Camera: Integrated C"
> 	bus_info                : "usb-0000:00:1a.0-1.6"
> 	version                 : 5.8.7
> 	capabilities            : 0x84a00001 [VIDEO_CAPTURE,?,?,STREAMING,(null)]
> 
> standards
> 
> inputs
> 
> video capture
> VIDIOC_G_FMT(VIDEO_CAPTURE): Invalid argument
> 
> controls
> 
> I don't understand the purpose of the second device (if any).  With
> tracing enabled, there are references to "entity 1" and "entity 2" in
> the kernel log.  Perhaps this is expected behavior?  If not, I would be
> happy to help debug further.

The second video node is for extracting metadata from the frames.
It is not expected to deliver video frames with a video capture application.

v4l-info should probably be updated to express that better, but I don't
know who maintains that tool

--
Kieran


> Thanks for all of your efforts maintaining uvcvideo!
> 
> Best,
> Kevin
> 
> [1]: https://www.ideasonboard.org/uvc/
> 
> 
> _______________________________________________
> Linux-uvc-devel mailing list
> Lin...@li...
> https://lists.sourceforge.net/lists/listinfo/linux-uvc-devel
> 

-- 
Regards
--
Kieran