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 <kieran.bingham@xxxxxxxxxxxxxxxx> --- 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<n>/streaming +Date: January 2023 +KernelVersion: 6.3 +Contact: Kieran Bingham <kieran.bingham@xxxxxxxxxxxxxxxx> +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 <media/v4l2-device.h> #include <media/v4l2-ioctl.h> #include <media/v4l2-event.h> +#include <media/videobuf2-core.h> #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, -- 2.34.1
