From patchwork Fri Dec 23 23:17:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kieran Bingham X-Patchwork-Id: 13081183 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 51714C4332F for ; Fri, 23 Dec 2022 23:17:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231410AbiLWXRs (ORCPT ); Fri, 23 Dec 2022 18:17:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231192AbiLWXRq (ORCPT ); Fri, 23 Dec 2022 18:17:46 -0500 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 589BF11808; Fri, 23 Dec 2022 15:17:44 -0800 (PST) Received: from Monstersaurus.local (cpc89244-aztw30-2-0-cust3082.18-1.cable.virginm.net [86.31.172.11]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 396ED4DD; Sat, 24 Dec 2022 00:17:41 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1671837461; bh=DRCjQnT/kw18dafqbNf3dcNvaDSQIX28MrmBKL7Y7TQ=; h=From:To:Cc:Subject:Date:From; b=hC47oqIhAEYWcviBHXg2RF+C8g6m7SBgmrS0DtMi2M2r6EKR/rMKH8+7oFOEKbJqQ GvHoxHKc9JH5/sZF0GRAtG/sxYPDbdAWGD1RIn9CxXlWGTBxDZpEtsERp9oMstbqHY kUWgOTNjULRfrdw17imkJFaTmpTQjqeTOmF69c9c= From: Kieran Bingham To: linux-media@vger.kernel.org Cc: Kieran Bingham , Mauro Carvalho Chehab , Sakari Ailus , Laurent Pinchart , Tomi Valkeinen , Hans Verkuil , Christophe JAILLET , linux-kernel@vger.kernel.org (open list) Subject: [RFC PATCH] media: v4l2-dev: sysfs: Support streaming attribute Date: Fri, 23 Dec 2022 23:17:35 +0000 Message-Id: <20221223231736.2111774-1-kieran.bingham@ideasonboard.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Provide a streaming attribute to allow userspace to interogate if a device is actively streaming or not. This will allow desktop notifications to report if a camera or device is active on the system, rather than just 'open' which can occur when configuring the device. Bug: https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/2669 Signed-off-by: Kieran Bingham --- This is a quick POC to see if such a facility makes sense. I'm weary that not all video devices may have the queues registered on the struct video_device, but this seems like an effective way to be able to determine if a device is actively streaming on a system. Documentation/ABI/stable/sysfs-class-video | 9 +++++++++ MAINTAINERS | 1 + drivers/media/v4l2-core/v4l2-dev.c | 13 +++++++++++++ 3 files changed, 23 insertions(+) create mode 100644 Documentation/ABI/stable/sysfs-class-video diff --git a/Documentation/ABI/stable/sysfs-class-video b/Documentation/ABI/stable/sysfs-class-video new file mode 100644 index 000000000000..99dd27475a92 --- /dev/null +++ b/Documentation/ABI/stable/sysfs-class-video @@ -0,0 +1,9 @@ +What: /sys/class/video4linux/video/streaming +Date: January 2023 +KernelVersion: 6.3 +Contact: Kieran Bingham +Description: + Indicates if the video device has an actively streaming queue. + This may indicate that the device is capturing or outputing + video data. +Users: diff --git a/MAINTAINERS b/MAINTAINERS index 11987154eeee..8449f5a6c0da 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12867,6 +12867,7 @@ S: Maintained W: https://linuxtv.org Q: http://patchwork.kernel.org/project/linux-media/list/ T: git git://linuxtv.org/media_tree.git +F: Documentation/ABI/stable/sysfs-class-video F: Documentation/admin-guide/media/ F: Documentation/devicetree/bindings/media/ F: Documentation/driver-api/media/ diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c index 397d553177fa..7d800309d076 100644 --- a/drivers/media/v4l2-core/v4l2-dev.c +++ b/drivers/media/v4l2-core/v4l2-dev.c @@ -30,6 +30,7 @@ #include #include #include +#include #define VIDEO_NUM_DEVICES 256 #define VIDEO_NAME "video4linux" @@ -85,7 +86,19 @@ static ssize_t name_show(struct device *cd, } static DEVICE_ATTR_RO(name); +static ssize_t streaming_show(struct device *cd, + struct device_attribute *attr, char *buf) +{ + struct video_device *vdev = to_video_device(cd); + + int active = vdev->queue ? vb2_is_streaming(vdev->queue) : false; + + return sprintf(buf, "%s\n", active ? "active" : "inactive"); +} +static DEVICE_ATTR_RO(streaming); + static struct attribute *video_device_attrs[] = { + &dev_attr_streaming.attr, &dev_attr_name.attr, &dev_attr_dev_debug.attr, &dev_attr_index.attr,