Hi Andrey,
thanks for the review
On Wed, Mar 25, 2020 at 11:42:27AM +0300, Andrey Konovalov wrote:
> 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@xxxxxxxxxx>
> > ---
> > 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)
Ups!
I should have noticed looking at V4L2_FL_REGISTERED=0 that these
flags are actually meant to be used as bit shifts. I can't say I like
the idea, but I should have known better than this.
I'll resend using set_bit() and test_bit().
Thanks for your help!
>
> 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.
> > *
> >
