Re: [RFC/PATCH v4 6/7] v4l: subdev: Control ioctls support

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Hi Laurent,

On Thursday, November 25, 2010 03:21:51 Laurent Pinchart wrote:
> Pass the control-related ioctls to the subdev driver through the core
> operations.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> ---
>  Documentation/video4linux/v4l2-framework.txt |   16 ++++++++++++++++
>  drivers/media/video/v4l2-subdev.c            |   24 ++++++++++++++++++++++++
>  2 files changed, 40 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/video4linux/v4l2-framework.txt b/Documentation/video4linux/v4l2-framework.txt
> index 4c9185a..f683f63 100644
> --- a/Documentation/video4linux/v4l2-framework.txt
> +++ b/Documentation/video4linux/v4l2-framework.txt
> @@ -336,6 +336,22 @@ argument to 0. Setting the argument to 1 will only enable device node
>  registration if the sub-device driver has set the V4L2_SUBDEV_FL_HAS_DEVNODE
>  flag.
>  
> +The device node handles a subset of the V4L2 API.
> +
> +VIDIOC_QUERYCTRL
> +VIDIOC_QUERYMENU
> +VIDIOC_G_CTRL
> +VIDIOC_S_CTRL
> +VIDIOC_G_EXT_CTRLS
> +VIDIOC_S_EXT_CTRLS
> +VIDIOC_TRY_EXT_CTRLS
> +
> +	The controls ioctls are identical to the ones defined in V4L2. They
> +	behave identically, with the only exception that they deal only with
> +	controls implemented in the sub-device. Depending on the driver, those
> +	controls can be also be accessed through one (or several) V4L2 device
> +	nodes.
> +
>  
>  I2C sub-device drivers
>  ----------------------
> diff --git a/drivers/media/video/v4l2-subdev.c b/drivers/media/video/v4l2-subdev.c
> index 0deff78..806ec30 100644
> --- a/drivers/media/video/v4l2-subdev.c
> +++ b/drivers/media/video/v4l2-subdev.c
> @@ -45,7 +45,31 @@ static int subdev_close(struct file *file)
>  
>  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);
> +
>  	switch (cmd) {
> +	case VIDIOC_QUERYCTRL:
> +		return v4l2_subdev_call(sd, core, queryctrl, arg);
> +
> +	case VIDIOC_QUERYMENU:
> +		return v4l2_subdev_call(sd, core, querymenu, arg);
> +
> +	case VIDIOC_G_CTRL:
> +		return v4l2_subdev_call(sd, core, g_ctrl, arg);
> +
> +	case VIDIOC_S_CTRL:
> +		return v4l2_subdev_call(sd, core, s_ctrl, arg);
> +
> +	case VIDIOC_G_EXT_CTRLS:
> +		return v4l2_subdev_call(sd, core, g_ext_ctrls, arg);
> +
> +	case VIDIOC_S_EXT_CTRLS:
> +		return v4l2_subdev_call(sd, core, s_ext_ctrls, arg);
> +
> +	case VIDIOC_TRY_EXT_CTRLS:
> +		return v4l2_subdev_call(sd, core, try_ext_ctrls, arg);
> +
>  	default:
>  		return -ENOIOCTLCMD;
>  	}
> 

I am very much in favor of replacing this with direct calls to the control
framework:

	case VIDIOC_QUERYCTRL:
		return v4l2_queryctrl(sd->ctrl_handler, arg);

This should promote the uptake of the control framework since that will simplify
subdev drivers (and provide the full functionality of all the control-related
ioctls).

This is a new feature, so we can enforce this here without breaking anything.

Regards,

	Hans

-- 
Hans Verkuil - video4linux developer - sponsored by Cisco
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