From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from galahad.ideasonboard.com ([185.26.127.97]:47911 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752633AbeBSQTQ (ORCPT ); Mon, 19 Feb 2018 11:19:16 -0500 From: Laurent Pinchart To: Guennadi Liakhovetski Cc: Kieran Bingham , Alexandre-Xavier =?ISO-8859-1?Q?Labont=E9=2DLamoureux?= , linux-media@vger.kernel.org Subject: Re: Bug: Two device nodes created in /dev for a single UVC webcam Date: Mon, 19 Feb 2018 18:19:55 +0200 Message-ID: <3383770.t3Sncl0gtc@avalon> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" Sender: linux-media-owner@vger.kernel.org List-ID: Hello, On Monday, 19 February 2018 15:58:40 EET Guennadi Liakhovetski wrote: > On Mon, 19 Feb 2018, Kieran Bingham wrote: > > On 17/02/18 20:47, Alexandre-Xavier Labont=E9-Lamoureux wrote: > >> Hi, > >>=20 > >> I'm running Linux 4.9.0-5-amd64 on Debian. I built the drivers from > >> the latest git and installed the modules. > >=20 > > Could you please be specific here? > >=20 > > Are you referring to linux-media/master branch or such? The latest from > > Linus' tree? > >=20 > > Please also detail the steps you have taken to reproduce this issue - a= nd > > of course - if you have made any code changes to make the latest UVC > > module compile against a v4.9 kernel... > >=20 > > 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. > >=20 > > 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. > >=20 > > (at least it didn't work cleanly when I tried to compile v4.15 against a > > v4.14 kernel last month) > >=20 > >> 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. > >=20 > > I believe Guennadi's latest work for handling meta-data (in the latest > > v4.16-rc1 I think) will create two device nodes. >=20 > That's correct. The lower index node (/dev/video0) is a video node, the > higher videoo node (/dev/video1) is a metadata node. >=20 > > > 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. > >=20 > > It would be expected that only the device with video functions as a > > streaming camera device, while the other would not. >=20 > Exactly. >=20 > > > My webcam has completely stopped working with Cheese and VLC. > >=20 > > This part is of particular concern however. > >=20 > > Guennadi - Have you tested Cheese/VLC with your series? >=20 > Sure, with cheese you can specify which camera you need by using its > --device=3D parameter. Eventually it's expected, that those programs will= be > updated to recognise metadata nodes and not attempt to use them. I've tested VLC (2.2.8) and haven't noticed any issue. If a program is=20 directed to the metadata video node and tries to capture video from it it w= ill=20 obviously fail. That being said, software that work today should continue=20 working, otherwise it's a regression, and we'll have to handle that. > > Are there any known issues that need looking at ? > >=20 > >>> v4l2-ctl --list-devices > >>=20 > >> Laptop_Integrated_Webcam_E4HD: (usb-0000:00:1a.0-1.5): > >> /dev/video0 > >> /dev/video1 > >>>=20 > >>> ls /dev/video* > >>=20 > >> /dev/video0 /dev/video1 =2D-=20 Regards, Laurent Pinchart