Re: [RFC/PATCH 5/6] v4l: subdev: Events support

["Hans Verkuil" <hverkuil@xs4all.nl>]

> From: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
>
> Provide v4l2_subdevs with v4l2_event support. Subdev drivers only need
> very
> little to support events.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
> Signed-off-by: David Cohen <david.cohen@nokia.com>
> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  Documentation/video4linux/v4l2-framework.txt |   18 +++++++
>  drivers/media/video/v4l2-subdev.c            |   71
> +++++++++++++++++++++++++-
>  include/media/v4l2-subdev.h                  |    9 +++
>  3 files changed, 97 insertions(+), 1 deletions(-)
>
> diff --git a/Documentation/video4linux/v4l2-framework.txt
> b/Documentation/video4linux/v4l2-framework.txt
> index f315858..2f5162c 100644
> --- a/Documentation/video4linux/v4l2-framework.txt
> +++ b/Documentation/video4linux/v4l2-framework.txt
> @@ -337,6 +337,24 @@ VIDIOC_TRY_EXT_CTRLS
>  	controls can be also be accessed through one (or several) V4L2 device
>  	nodes.
>
> +VIDIOC_DQEVENT
> +VIDIOC_SUBSCRIBE_EVENT
> +VIDIOC_UNSUBSCRIBE_EVENT
> +
> +	The events ioctls are identical to the ones defined in V4L2. They
> +	behave identically, with the only exception that they deal only with
> +	events generated by the sub-device. Depending on the driver, those
> +	events can also be reported by one (or several) V4L2 device nodes.
> +
> +	Sub-device drivers that want to use events need to set the
> +	V4L2_SUBDEV_USES_EVENTS v4l2_subdev::flags and initialize
> +	v4l2_subdev::nevents to events queue depth before registering the
> +	sub-device. After registration events can be queued as usual on the
> +	v4l2_subdev::devnode device node.
> +
> +	To properly support events, the poll() file operation is also
> +	implemented.
> +
>
>  I2C sub-device drivers
>  ----------------------
> diff --git a/drivers/media/video/v4l2-subdev.c
> b/drivers/media/video/v4l2-subdev.c
> index 141098b..7191a4b 100644
> --- a/drivers/media/video/v4l2-subdev.c
> +++ b/drivers/media/video/v4l2-subdev.c
> @@ -18,26 +18,64 @@
>   *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
> USA
>   */
>
> -#include <linux/types.h>
>  #include <linux/ioctl.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
>  #include <linux/videodev2.h>
>
>  #include <media/v4l2-device.h>
>  #include <media/v4l2-ioctl.h>
> +#include <media/v4l2-fh.h>
> +#include <media/v4l2-event.h>
>
>  static int subdev_open(struct file *file)
>  {
>  	struct video_device *vdev = video_devdata(file);
>  	struct v4l2_subdev *sd = vdev_to_v4l2_subdev(vdev);
> +	struct v4l2_fh *vfh;
> +	int ret;
>
>  	if (!sd->initialized)
>  		return -EAGAIN;
>
> +	vfh = kzalloc(sizeof(*vfh), GFP_KERNEL);
> +	if (vfh == NULL)
> +		return -ENOMEM;
> +
> +	ret = v4l2_fh_init(vfh, vdev);
> +	if (ret)
> +		goto err;
> +
> +	if (sd->flags & V4L2_SUBDEV_USES_EVENTS) {
> +		ret = v4l2_event_init(vfh);
> +		if (ret)
> +			goto err;
> +
> +		ret = v4l2_event_alloc(vfh, sd->nevents);
> +		if (ret)
> +			goto err;
> +	}
> +
> +	v4l2_fh_add(vfh);
> +	file->private_data = vfh;
> +
>  	return 0;
> +
> +err:
> +	v4l2_fh_exit(vfh);
> +	kfree(vfh);
> +
> +	return ret;
>  }
>
>  static int subdev_close(struct file *file)
>  {
> +	struct v4l2_fh *vfh = file->private_data;
> +
> +	v4l2_fh_del(vfh);
> +	v4l2_fh_exit(vfh);
> +	kfree(vfh);
> +
>  	return 0;
>  }
>
> @@ -45,6 +83,7 @@ static long subdev_do_ioctl(struct file *file, unsigned
> int cmd, void *arg)
>  {
>  	struct video_device *vdev = video_devdata(file);
>  	struct v4l2_subdev *sd = vdev_to_v4l2_subdev(vdev);
> +	struct v4l2_fh *fh = file->private_data;
>
>  	switch (cmd) {
>  	case VIDIOC_QUERYCTRL:
> @@ -68,6 +107,18 @@ static long subdev_do_ioctl(struct file *file,
> unsigned int cmd, void *arg)
>  	case VIDIOC_TRY_EXT_CTRLS:
>  		return v4l2_subdev_call(sd, core, try_ext_ctrls, arg);
>
> +	case VIDIOC_DQEVENT:
> +		if (!(sd->flags & V4L2_SUBDEV_USES_EVENTS))
> +			return -ENOIOCTLCMD;
> +
> +		return v4l2_event_dequeue(fh, arg, file->f_flags & O_NONBLOCK);
> +
> +	case VIDIOC_SUBSCRIBE_EVENT:
> +		return v4l2_subdev_call(sd, core, subscribe_event, fh, arg);
> +
> +	case VIDIOC_UNSUBSCRIBE_EVENT:
> +		return v4l2_subdev_call(sd, core, unsubscribe_event, fh, arg);
> +
>  	default:
>  		return -ENOIOCTLCMD;
>  	}
> @@ -81,11 +132,29 @@ static long subdev_ioctl(struct file *file, unsigned
> int cmd,
>  	return video_usercopy(file, cmd, arg, subdev_do_ioctl);
>  }
>
> +static unsigned int subdev_poll(struct file *file, poll_table *wait)
> +{
> +	struct video_device *vdev = video_devdata(file);
> +	struct v4l2_subdev *sd = vdev_to_v4l2_subdev(vdev);
> +	struct v4l2_fh *fh = file->private_data;
> +
> +	if (!(sd->flags & V4L2_SUBDEV_USES_EVENTS))
> +		return POLLERR;
> +
> +	poll_wait(file, &fh->events->wait, wait);
> +
> +	if (v4l2_event_pending(fh))
> +		return POLLPRI;
> +
> +	return 0;
> +}
> +
>  const struct v4l2_file_operations v4l2_subdev_fops = {
>  	.owner = THIS_MODULE,
>  	.open = subdev_open,
>  	.unlocked_ioctl = subdev_ioctl,
>  	.release = subdev_close,
> +	.poll = subdev_poll,
>  };
>
>  void v4l2_subdev_init(struct v4l2_subdev *sd, const struct
> v4l2_subdev_ops *ops)
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 7b6edcd..803d7bd 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -36,6 +36,8 @@
>  #define V4L2_SUBDEV_IR_TX_FIFO_SERVICE_REQ	0x00000001
>
>  struct v4l2_device;
> +struct v4l2_event_subscription;
> +struct v4l2_fh;
>  struct v4l2_subdev;
>  struct tuner_setup;
>
> @@ -134,6 +136,10 @@ struct v4l2_subdev_core_ops {
>  	int (*s_register)(struct v4l2_subdev *sd, struct v4l2_dbg_register
> *reg);
>  #endif
>  	int (*s_power)(struct v4l2_subdev *sd, int on);
> +	int (*subscribe_event)(struct v4l2_subdev *sd, struct v4l2_fh *fh,
> +			       struct v4l2_event_subscription *sub);
> +	int (*unsubscribe_event)(struct v4l2_subdev *sd, struct v4l2_fh *fh,
> +				 struct v4l2_event_subscription *sub);
>  };
>
>  /* s_mode: switch the tuner to a specific tuner mode. Replacement of
> s_radio.
> @@ -406,6 +412,7 @@ struct v4l2_subdev_ops {
>  #define V4L2_SUBDEV_FL_IS_I2C (1U << 0)
>  /* Set this flag if this subdev is a spi device. */
>  #define V4L2_SUBDEV_FL_IS_SPI (1U << 1)
> +#define V4L2_SUBDEV_USES_EVENTS	(1U << 2)

Recommend renaming to V4L2_SUBDEV_FL_HAS_EVENTS.

The prefix is consistent with the other flags and 'has events' feels more
natural to me.

>
>  /* Each instance of a subdev driver should create this struct, either
>     stand-alone or embedded in a larger struct.
> @@ -425,6 +432,8 @@ struct v4l2_subdev {
>  	/* subdev device node */
>  	struct video_device devnode;
>  	unsigned int initialized;
> +	/* number of events to be allocated on open */
> +	unsigned int nevents;
>  };
>
>  #define vdev_to_v4l2_subdev(vdev) \
> --
> 1.7.1
>
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Reviewed-by: Hans Verkuil <hverkuil@xs4all.nl>

Regards,

        Hans

-- 
Hans Verkuil - video4linux developer - sponsored by TANDBERG, part of Cisco