Re: [PATCH 6.1.y-cip 49/55] media: v4l2-subdev: Refactor events

[Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>]

Hi Pavel,

On Wed, Aug 20, 2025 at 06:04:05PM +0200, Tommaso Merciai wrote:
> From: Tommaso Merciai <tomm.merciai@gmail.com>
> 
> commit e7724e23196ab1b4bc843aa60e917967d95697e4 upstream.
> 
> Controls can be exposed to userspace via a v4l-subdevX device, and
> userspace has to be able to subscribe to control events so that it is
> notified when the control changes value. If a control handler is set for
> the subdev then set the HAS_EVENTS flag automatically into
> v4l2_subdev_init_finalize() and use v4l2_ctrl_subdev_subscribe_event() and
> v4l2_event_subdev_unsubscribe() as default if subdev don't have
> .(un)subscribe control operations. This simplifies subdev drivers by
> avoiding the need to set the V4L2_SUBDEV_FL_HAS_EVENTS flag and plug the
> event handlers, and ensures consistency of the API exposed to userspace.
> 
> Signed-off-by: Tommaso Merciai <tomm.merciai@gmail.com>
> Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> ---
>  drivers/media/v4l2-core/v4l2-subdev.c | 22 ++++++++++++++++++++--
>  1 file changed, 20 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 5c27bac772ea..423e9663d149 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -502,10 +502,25 @@ static long subdev_do_ioctl(struct file *file, unsigned int cmd, void *arg,
>  		return v4l2_event_dequeue(vfh, arg, file->f_flags & O_NONBLOCK);
>  
>  	case VIDIOC_SUBSCRIBE_EVENT:
> -		return v4l2_subdev_call(sd, core, subscribe_event, vfh, arg);
> +		if (v4l2_subdev_has_op(sd, core, subscribe_event))
> +			return v4l2_subdev_call(sd, core, subscribe_event,
> +						vfh, arg);
> +
> +		if ((sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS) &&
> +		    vfh->ctrl_handler)
> +			return v4l2_ctrl_subdev_subscribe_event(sd, vfh, arg);
> +
> +		return -ENOIOCTLCMD;
>  
>  	case VIDIOC_UNSUBSCRIBE_EVENT:
> -		return v4l2_subdev_call(sd, core, unsubscribe_event, vfh, arg);
> +		if (v4l2_subdev_has_op(sd, core, unsubscribe_event))
> +			return v4l2_subdev_call(sd, core, unsubscribe_event,
> +						vfh, arg);
> +
> +		if (sd->flags & V4L2_SUBDEV_FL_HAS_EVENTS)
> +			return v4l2_event_subdev_unsubscribe(sd, vfh, arg);
> +
> +		return -ENOIOCTLCMD;
>  
>  #ifdef CONFIG_VIDEO_ADV_DEBUG
>  	case VIDIOC_DBG_G_REGISTER:
> @@ -1023,6 +1038,9 @@ int __v4l2_subdev_init_finalize(struct v4l2_subdev *sd, const char *name,
>  {
>  	struct v4l2_subdev_state *state;
>  
> +	if (sd->ctrl_handler)
> +		sd->flags |= V4L2_SUBDEV_FL_HAS_EVENTS;
> +
>  	state = __v4l2_subdev_state_alloc(sd, name, key);
>  	if (IS_ERR(state))
>  		return PTR_ERR(state);
> -- 
> 2.43.0
> 

With OV5645 part can we gently drop also this one?
Thanks for your work!


Regards
Tommaso