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Subject: Re: [PATCH] media: imx: queue subdev events to reachable video
 devices
To:     Steve Longerbeam <slongerbeam@gmail.com>,
        linux-media@vger.kernel.org
Cc:     Philipp Zabel <p.zabel@pengutronix.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "open list:STAGING SUBSYSTEM" <devel@driverdev.osuosl.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20181209195722.26858-1-steve_longerbeam@mentor.com>
From:   Hans Verkuil <hverkuil@xs4all.nl>
Message-ID: <2bd52738-f466-96d8-5877-aab96a129e74@xs4all.nl>
Date:   Tue, 8 Jan 2019 14:26:38 +0100
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On 12/09/18 20:57, Steve Longerbeam wrote:
> From: Steve Longerbeam <slongerbeam@gmail.com>
> 
> Forward events from a sub-device to its list of reachable video
> devices.
> 
> Note this will queue the event to a video device even if there is
> no actual _enabled_ media path from the sub-device to the video device.
> So a future improvement is to skip the video device if there is no enabled
> path to it from the sub-device. The entity->pipe pointer can't be
> used for this check because in imx-media a sub-device can be a
> member to more than one streaming pipeline at a time.

You explain what you are doing, but I am missing an explanation of *why*
this is needed.

> 
> Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
> ---
>  drivers/staging/media/imx/imx-media-capture.c | 18 ++++++++++++++
>  drivers/staging/media/imx/imx-media-dev.c     | 24 +++++++++++++++++++
>  2 files changed, 42 insertions(+)
> 
> diff --git a/drivers/staging/media/imx/imx-media-capture.c b/drivers/staging/media/imx/imx-media-capture.c
> index b37e1186eb2f..4dfbe05d203e 100644
> --- a/drivers/staging/media/imx/imx-media-capture.c
> +++ b/drivers/staging/media/imx/imx-media-capture.c
> @@ -335,6 +335,21 @@ static int capture_s_parm(struct file *file, void *fh,
>  	return 0;
>  }
>  
> +static int capture_subscribe_event(struct v4l2_fh *fh,
> +				   const struct v4l2_event_subscription *sub)
> +{
> +	switch (sub->type) {
> +	case V4L2_EVENT_IMX_FRAME_INTERVAL_ERROR:
> +		return v4l2_event_subscribe(fh, sub, 0, NULL);
> +	case V4L2_EVENT_SOURCE_CHANGE:
> +		return v4l2_src_change_event_subscribe(fh, sub);
> +	case V4L2_EVENT_CTRL:
> +		return v4l2_ctrl_subscribe_event(fh, sub);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
>  static const struct v4l2_ioctl_ops capture_ioctl_ops = {
>  	.vidioc_querycap	= vidioc_querycap,
>  
> @@ -362,6 +377,9 @@ static const struct v4l2_ioctl_ops capture_ioctl_ops = {
>  	.vidioc_expbuf		= vb2_ioctl_expbuf,
>  	.vidioc_streamon	= vb2_ioctl_streamon,
>  	.vidioc_streamoff	= vb2_ioctl_streamoff,
> +
> +	.vidioc_subscribe_event = capture_subscribe_event,
> +	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
>  };

This part of the patch adds event support to the capture device, can't this be
split up into a separate patch? It seems to be useful in its own right.

>  
>  /*
> diff --git a/drivers/staging/media/imx/imx-media-dev.c b/drivers/staging/media/imx/imx-media-dev.c
> index 4b344a4a3706..25e916562c66 100644
> --- a/drivers/staging/media/imx/imx-media-dev.c
> +++ b/drivers/staging/media/imx/imx-media-dev.c
> @@ -442,6 +442,29 @@ static const struct media_device_ops imx_media_md_ops = {
>  	.link_notify = imx_media_link_notify,
>  };
>  
> +static void imx_media_notify(struct v4l2_subdev *sd,
> +			     unsigned int notification,
> +			     void *arg)
> +{
> +	struct media_entity *entity = &sd->entity;
> +	int i;
> +
> +	if (notification != V4L2_DEVICE_NOTIFY_EVENT)
> +		return;
> +
> +	for (i = 0; i < entity->num_pads; i++) {
> +		struct media_pad *pad = &entity->pads[i];
> +		struct imx_media_pad_vdev *pad_vdev;
> +		struct list_head *pad_vdev_list;
> +
> +		pad_vdev_list = to_pad_vdev_list(sd, pad->index);
> +		if (!pad_vdev_list)
> +			continue;
> +		list_for_each_entry(pad_vdev, pad_vdev_list, list)
> +			v4l2_event_queue(pad_vdev->vdev->vfd, arg);

Which events do you want to forward? E.g. forwarding control events
doesn't seem right, but other events may be useful. Are those events
also appearing on the v4l-subdevX device? And if so, should they?

> +	}
> +}
> +
>  static int imx_media_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -462,6 +485,7 @@ static int imx_media_probe(struct platform_device *pdev)
>  	mutex_init(&imxmd->mutex);
>  
>  	imxmd->v4l2_dev.mdev = &imxmd->md;
> +	imxmd->v4l2_dev.notify = imx_media_notify;
>  	strscpy(imxmd->v4l2_dev.name, "imx-media",
>  		sizeof(imxmd->v4l2_dev.name));
>  
> 

Regards,

	Hans