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

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Alexandre-Xavier,

On Sunday, 25 February 2018 10:19:51 EET Alexandre-Xavier Labonté-Lamoureux 
wrote:
> Hi Laurent,
> 
> Sorry for the late reply.
> 
> I've been trying to reproduce the issue again. I cloned the entire
> media repository later during the week and I haven't been able to
> reproduce the issue after I installed the modules. A metadata node is
> no longer created for my webcam. The four commits that you've
> mentioned are still in the commit log, so it seems that they didn't
> break anything.

Now that's weird. I would expect a metadata video node to be created if the 
patches I mentioned are applied. Are you sure you have loaded the modules 
corresponding to the compiled sources ?

> I'm not sure what could have changed that would have caused it to work
> fine this time. I believe that I'm in the correct branch.
> 
> $ git status
> On branch media_tree/master
> Your branch is up-to-date with 'r_media_tree/master'.
> 
> I probably did `./build` instead of `./build --main-git` the first time.
> 
> On Mon, Feb 19, 2018 at 2:10 PM, Laurent Pinchart wrote:
> > On Monday, 19 February 2018 19:29:24 EET Alexandre-Xavier
> > Labonté-Lamoureux wrote:
> >> Hi Kieran,
> >> 
> >> This is how I built the drivers:
> >> 
> >> $ git clone --depth=1 git://linuxtv.org/media_build.git
> >> $ cd media_build
> >> $ ./build --main-git
> >> 
> >> I then installed the newly built kernel modules:
> >> 
> >> $ sudo make install
> >> 
> >> Once the modules were updated, I restarted my computer to make sure
> >> every module got reloaded. I didn't make any changes to the code and I
> >> found the issues after trying each of those programs individually
> >> after I restarted my computer.
> >> 
> >> This was the latest commit when I cloned the repo:
> >> 
> >> commit d144cfe4b3c37ece55ae27778c99765d4943c4fa
> >> Author: Jasmin Jessich <jasmin@anw.at>
> >> Date:   Fri Feb 16 22:40:49 2018 +0100
> >> 
> >>     Re-generated v3.12_kfifo_in.patch
> >> 
> >> My version of VLC is 2.2.6. Here's a copy of the relevant data of
> >> VLC's log file in case it can help: https://paste.debian.net/1011025/
> >> In this case, I tried to open /dev/video0 first and /dev/video1 second.
> >> 
> >> I can also try with ffplay:
> >> $ ffplay /dev/video0
> >> 
> >> I get this: [video4linux2,v4l2 @ 0x7f2160000920]
> >> ioctl(VIDIOC_STREAMON): Message too long
> >> /dev/video0: Message too long
> >> 
> >> A new message appears in dmesg: uvcvideo: Failed to submit URB 0 (-90).
> > 
> > That's interesting, and possibly unrelated to the patch series that added
> > metadata capture support. Would you be able to revert that patch series
> > and see if the problem still occurs ? The four commits to be reverted are
> > 
> > 088ead25524583e2200aa99111bea2f66a86545a
> > 3bc85817d7982ed53fbc9b150b0205beff68ca5c
> > 94c53e26dc74744cc4f9a8ddc593b7aef96ba764
> > 31a96f4c872e8fb953c853630f69d5de6ec961c9
> > 
> > And if you could bisect the issue it would be even better :-)
> > 
> > Could you also send me the output of lsusb -v for your camera (you can
> > restrict it to the camera with -d VID:PID), running as root if possible ?
> > 
> >> $ ffplay /dev/video1
> >> 
> >> I get this:
> >> [video4linux2,v4l2 @ 0x7f00ec000920] ioctl(VIDIOC_G_INPUT):
> >> Inappropriate ioctl for device
> >> /dev/video1: Inappropriate ioctl for device
> >> 
> >> Like Guennadi said, /dev/video1 is a metadata node, so I don't expect
> >> it to work. In the case of /dev/video0, I can't tell what could be
> >> wrong from the error message.

-- 
Regards,

Laurent Pinchart