Re: Bug: Two device nodes created in /dev for a single UVC webcam

[Kieran Bingham <kieran.bingham@ideasonboard.com>]

Hi Alexandre,

Thankyou for your bug report,

On 17/02/18 20:47, Alexandre-Xavier Labonté-Lamoureux wrote:
> Hi,
> 
> I'm running Linux 4.9.0-5-amd64 on Debian. I built the drivers from
> the latest git and installed the modules.

Could you please be specific here?

Are you referring to linux-media/master branch or such? The latest from Linus' tree?

Please also detail the steps you have taken to reproduce this issue - and of
course - if you have made any code changes to make the latest UVC module compile
against a v4.9 kernel...

Building the latest git tree and installing as a module on a v4.9 kernel is
quite a leap... I wouldn't have expected that to work.

The code would have to be compiled against a v4.9 kernel directly, and I didn't
think compiling the UVC driver against older kernels worked.

(at least it didn't work cleanly when I tried to compile v4.15 against a v4.14
kernel last month)

> Now, two device nodes are
> created for my webcam. This is not normal as it has never happened to
> me before. If I connect another webcam to my laptop, two more device
> nodes will be created for this webcam. So two new device nodes are
> created for a single webcam.

I believe Guennadi's latest work for handling meta-data (in the latest v4.16-rc1
I think) will create two device nodes.


> The name of my webcam appears twice in the device comobox in Guvcview
> because of this. One of them will not work if I select it.

It would be expected that only the device with video functions as a streaming
camera device, while the other would not.


> My webcam has completely stopped working with Cheese and VLC.

This part is of particular concern however.

Guennadi - Have you tested Cheese/VLC with your series?

Are there any known issues that need looking at ?

>> v4l2-ctl --list-devices
> Laptop_Integrated_Webcam_E4HD:  (usb-0000:00:1a.0-1.5):
>     /dev/video0
>     /dev/video1
> 
>> ls /dev/video*
> /dev/video0  /dev/video1
>
> Have a nice day,
> Alexandre-Xavier

Regards

Kieran Bingham