From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C3D2C4332F for ; Wed, 21 Dec 2022 22:26:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235010AbiLUW0h (ORCPT ); Wed, 21 Dec 2022 17:26:37 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37542 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235072AbiLUW0B (ORCPT ); Wed, 21 Dec 2022 17:26:01 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [IPv6:2001:4b98:dc2:55:216:3eff:fef7:d647]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A59927CCA; Wed, 21 Dec 2022 14:24:56 -0800 (PST) Received: from pendragon.ideasonboard.com (213-243-189-158.bb.dnainternet.fi [213.243.189.158]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 30312FB; Wed, 21 Dec 2022 23:24:49 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1671661489; bh=s5eSNgL2lpm7DGCvQ+qHJzSxetOZHsmF+SXHjPAgiME=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GuzIlnO+GKfMICmTyQbNGpxwj1PQLBwQH1f2HQbKgPFnd/zy41Gf8iACC99n7tNNw HD4Cgr/E7lBeuSNYarvn6umRURalzElINND2T+nxlaIcAC44eHErxTNSLkSswEw2bP p4upBTq2HIEVAE7/MWRn0JGRdI0lC5r3jHzGxQzY= Date: Thu, 22 Dec 2022 00:24:44 +0200 From: Laurent Pinchart To: Mauro Carvalho Chehab Cc: Ricardo Ribalda , Yunke Cao , Sergey Senozhatsky , linux-media@vger.kernel.org, Mauro Carvalho Chehab , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 3/3] media: uvcvideo: Add a unique suffix to camera names Message-ID: References: <20220920-resend-meta-v4-0-3ac355b66723@chromium.org> <20220920-resend-meta-v4-3-3ac355b66723@chromium.org> <20221221220248.12395efb@sal.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20221221220248.12395efb@sal.lan> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mauro, On Wed, Dec 21, 2022 at 10:02:48PM +0000, Mauro Carvalho Chehab wrote: > Em Tue, 6 Dec 2022 00:02:22 +0100 Ricardo Ribalda escreveu: > > On Mon, 5 Dec 2022 at 23:16, Laurent Pinchart wrote: > > > On Fri, Dec 02, 2022 at 06:08:19PM +0100, Ricardo Ribalda wrote: > > > > Some cameras have multiple data inputs (i.e. IR sensor and RGB sensor), > > > > append a unique number to the device name. > > > > > > > > Fixes v4l2-compliance: > > > > Media Controller ioctls: > > > > fail: v4l2-test-media.cpp(205): v2_entity_names_set.find(key) != v2_entity_names_set.end() > > > > test MEDIA_IOC_G_TOPOLOGY: FAIL > > > > fail: v4l2-test-media.cpp(394): num_data_links != num_links > > > > test MEDIA_IOC_ENUM_ENTITIES/LINKS: FAIL > > > > > > > > Signed-off-by: Ricardo Ribalda > > > > --- > > > > drivers/media/usb/uvc/uvc_driver.c | 3 ++- > > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c > > > > index 215fb483efb0..f4032ebb3689 100644 > > > > --- a/drivers/media/usb/uvc/uvc_driver.c > > > > +++ b/drivers/media/usb/uvc/uvc_driver.c > > > > @@ -1963,7 +1963,8 @@ int uvc_register_video_device(struct uvc_device *dev, > > > > break; > > > > } > > > > > > > > - strscpy(vdev->name, dev->name, sizeof(vdev->name)); > > > > + snprintf(vdev->name, sizeof(vdev->name), "%s %u", dev->name, > > > > + stream->header.bTerminalLink); > > > > > > This won't be perfect as the string is not guaranteed to fit in > > > vdev->name, but I suppose it will help as a quick fix for some devices. > > > How about the other devices ? Won't they still exhibit the above > > > v4l2-compliance failure ? Isn't that something that will still affect > > > Chrome OS devices ? > > > > We could place the id first... but that will look bad: Eg: > > > > 1- My favorite camera > > > > Another option is to remove the last chars to fit the id. Eg: > > > > My favorite came-1 > > > > If you prefer any of those options or have a better idea I can implement that. > > > > > The change should not cause any regression as big as in patch 1/3. > > > However, unless I'm mistaken users will notice a device name change, > > > especially when selecting a device in their web browser. Could that be a > > > problem ? > > > > I think the only side effect is that the first time that the kernel > > changes the naming convention, if there are more than one camera on > > the system, the video conference might pick a different camera. > > The good news is that the user will be presented with cameras with > > different names. Now some cameras show very confusing names: > > > > ribalda@alco:~/work/linux$ for a in /dev/video* ; do yavta -l $a| grep > > "Dell Webcam"; done > > Device `Dell Webcam WB7022' on `usb-0000:2d:00.0-1.2.3.1' (driver > > 'uvcvideo') supports video, capture, without mplanes. > > Device `Dell Webcam WB7022' on `usb-0000:2d:00.0-1.2.3.1' (driver > > 'uvcvideo') supports meta-data, capture, without mplanes. > > Device `Dell Webcam WB7022' on `usb-0000:2d:00.0-1.2.3.1' (driver > > 'uvcvideo') supports video, capture, without mplanes. > > Device `Dell Webcam WB7022' on `usb-0000:2d:00.0-1.2.3.1' (driver > > 'uvcvideo') supports meta-data, capture, without mplanes. > > That is bad, as some apps like camorama actually store the user > preferences (last used resolution and fps), preserving them the next > time the camera with the same name is used. > > In the specific case of camorama, it uses the by-id filename, which is > derived from the name, as stored at: > > $ ls -la /dev/v4l/by-id/usb-Quanta_HD_Camera_0001-video-index* > lrwxrwxrwx 1 root root 12 dez 21 09:59 /dev/v4l/by-id/usb-Quanta_HD_Camera_0001-video-index0 -> ../../video0 > lrwxrwxrwx 1 root root 12 dez 21 09:59 /dev/v4l/by-id/usb-Quanta_HD_Camera_0001-video-index1 -> ../../video1 > > With this change, not only the camera name will become bigger (and may > end losing the index0/index1 data), but it will also lost the stored > preferences on apps like camorama, causing regressions. > > It sounds a lot easier to teach udev to change the name on an unique > way, on machines where you need it. It's not a udev issue, it's an API compliance problem, entity names in a media controller graph must be unique, and they are not. Losing the stored preference is possibly inconvenient in some cases, but I don't think it's a real blocker. -- Regards, Laurent Pinchart