linux-kernel - Re: [PATCH] media: i2c: ov5645: add HAS

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Message-ID: <20241014175452.GB13238@pendragon.ideasonboard.com>
Date: Mon, 14 Oct 2024 20:54:52 +0300
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Tommaso Merciai <tomm.merciai@...il.com>
Cc: sakari.ailus@...ux.intel.com,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: i2c: ov5645: add HAS_EVENTS support

Hi Tommaso,

Thank you for the patch.

On Mon, Oct 14, 2024 at 07:38:40PM +0200, Tommaso Merciai wrote:
> 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.
> Add missing HAS_EVENTS support: flag and .(un)subscribe_event().
> 
> Signed-off-by: Tommaso Merciai <tomm.merciai@...il.com>
> ---
>  drivers/media/i2c/ov5645.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/i2c/ov5645.c b/drivers/media/i2c/ov5645.c
> index 0c32bd2940ec..2c5145d5c616 100644
> --- a/drivers/media/i2c/ov5645.c
> +++ b/drivers/media/i2c/ov5645.c
> @@ -29,6 +29,7 @@
>  #include <linux/slab.h>
>  #include <linux/types.h>
>  #include <media/v4l2-ctrls.h>
> +#include <media/v4l2-event.h>
>  #include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
>  
> @@ -1034,6 +1035,11 @@ static const struct v4l2_subdev_video_ops ov5645_video_ops = {
>  	.s_stream = ov5645_s_stream,
>  };
>  
> +static const struct v4l2_subdev_core_ops ov5645_subdev_core_ops = {
> +	.subscribe_event = v4l2_ctrl_subdev_subscribe_event,
> +	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
> +};
> +
>  static const struct v4l2_subdev_pad_ops ov5645_subdev_pad_ops = {
>  	.enum_mbus_code = ov5645_enum_mbus_code,
>  	.enum_frame_size = ov5645_enum_frame_size,
> @@ -1043,6 +1049,7 @@ static const struct v4l2_subdev_pad_ops ov5645_subdev_pad_ops = {
>  };
>  
>  static const struct v4l2_subdev_ops ov5645_subdev_ops = {
> +	.core = &ov5645_subdev_core_ops,
>  	.video = &ov5645_video_ops,
>  	.pad = &ov5645_subdev_pad_ops,
>  };
> @@ -1178,7 +1185,8 @@ static int ov5645_probe(struct i2c_client *client)
>  
>  	v4l2_i2c_subdev_init(&ov5645->sd, client, &ov5645_subdev_ops);
>  	ov5645->sd.internal_ops = &ov5645_internal_ops;
> -	ov5645->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	ov5645->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE |
> +			    V4L2_SUBDEV_FL_HAS_EVENTS;

Instead of patching every subdev driver, should we handle all of this in
the subdev core ? If a control handler is set for the subdev, we could
set the HAS_EVENTS flag automatically, and default to
v4l2_ctrl_subdev_subscribe_event() and v4l2_event_subdev_unsubscribe()
if there are no control operations.

>  	ov5645->pad.flags = MEDIA_PAD_FL_SOURCE;
>  	ov5645->sd.dev = &client->dev;
>  	ov5645->sd.entity.function = MEDIA_ENT_F_CAM_SENSOR;

-- 
Regards,

Laurent Pinchart