[libcamera-devel] [PATCH 2/4] media: v4l2-dev: Add v4l2_device_register_ro_subdev_node()
Andrey Konovalov
andrey.konovalov at linaro.org
Wed Mar 25 09:42:27 CET 2020
Hi Jacopo,
Thank you for your patch set!
On 24.03.2020 23:28, Jacopo Mondi wrote:
> Add to the V4L2 code a function to register device nodes for video
> subdevices in read-only mode.
>
> Registering a device node in read-only mode is useful to expose to
> userspace the current sub-device configuration, without allowing
> application to change it by using the V4L2 subdevice ioctls.
>
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
> drivers/media/v4l2-core/v4l2-device.c | 16 +++++++++++++++-
> drivers/media/v4l2-core/v4l2-subdev.c | 19 +++++++++++++++++++
> include/media/v4l2-dev.h | 7 +++++++
> include/media/v4l2-device.h | 10 ++++++++++
> 4 files changed, 51 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c
> index 63d6b147b21e..6f9dba36eda1 100644
> --- a/drivers/media/v4l2-core/v4l2-device.c
> +++ b/drivers/media/v4l2-core/v4l2-device.c
> @@ -188,7 +188,8 @@ static void v4l2_device_release_subdev_node(struct video_device *vdev)
> kfree(vdev);
> }
>
> -int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> +int __v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev,
> + bool read_only)
> {
> struct video_device *vdev;
> struct v4l2_subdev *sd;
> @@ -217,6 +218,8 @@ int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
> vdev->fops = &v4l2_subdev_fops;
> vdev->release = v4l2_device_release_subdev_node;
> vdev->ctrl_handler = sd->ctrl_handler;
> + if (read_only)
> + vdev->flags |= V4L2_FL_RO_DEVNODE;
<snip>
> @@ -331,6 +331,7 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg)
> struct v4l2_fh *vfh = file->private_data;
> #if defined(CONFIG_VIDEO_V4L2_SUBDEV_API)
> struct v4l2_subdev_fh *subdev_fh = to_v4l2_subdev_fh(vfh);
> + bool ro_devnode = !!(vdev->flags & V4L2_FL_RO_DEVNODE);
So V4L2_FL_RO_DEVNODE is a bit mask, ...
<snip>
> diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
> index 48531e57cc5a..029873a338f2 100644
> --- a/include/media/v4l2-dev.h
> +++ b/include/media/v4l2-dev.h
> @@ -82,11 +82,18 @@ struct v4l2_ctrl_handler;
> * but the old crop API will still work as expected in order to preserve
> * backwards compatibility.
> * Never set this flag for new drivers.
> + * @V4L2_FL_RO_DEVNODE:
> + * indicates that the video device node is registered in read-only mode.
> + * The flag only applies to device nodes registered for sub-devices, it is
> + * set by the core when the sub-devices device nodes are registered with
> + * v4l2_device_register_ro_subdev_nodes() and used by the sub-device ioctl
> + * handler to restrict access to some ioctl calls.
> */
> enum v4l2_video_device_flags {
> V4L2_FL_REGISTERED = 0,
> V4L2_FL_USES_V4L2_FH = 1,
> V4L2_FL_QUIRK_INVERTED_CROP = 2,
> + V4L2_FL_RO_DEVNODE = 3,
... then V4L2_FL_RO_DEVNODE should rather be equal to 4, than to (V4L2_FL_USES_V4L2_FH | V4L2_FL_QUIRK_INVERTED_CROP)
Thanks,
Andrey
> };
>
> /* Priority helper functions */
> diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
> index e0b8f2602670..0df667ba9938 100644
> --- a/include/media/v4l2-device.h
> +++ b/include/media/v4l2-device.h
> @@ -183,6 +183,16 @@ void v4l2_device_unregister_subdev(struct v4l2_subdev *sd);
> int __must_check
> v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev);
>
> +/**
> + * v4l2_device_register_ro_subdev_nodes - Registers read-only device nodes for
> + * all subdevs of the v4l2 device that are marked with the
> + * %V4L2_SUBDEV_FL_HAS_DEVNODE flag.
> + *
> + * @v4l2_dev: pointer to struct v4l2_device
> + */
> +int __must_check
> +v4l2_device_register_ro_subdev_nodes(struct v4l2_device *v4l2_dev);
> +
> /**
> * v4l2_subdev_notify - Sends a notification to v4l2_device.
> *
>
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