Re: [PATCH v3 1/2] rcar-vin: Stop stream when subdevice signal EOS

[Hans Verkuil <hverkuil-cisco@xs4all.nl>]

Hi Niklas,

On 10/03/2021 17:45, Niklas Söderlund wrote:
> When a subdevice signals end of stream stop the VIN in addition to
> informing user-space of the event.
> 
> Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> Reviewed-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
> ---
> * Changes since v2
> - Log using vin_dbg() instead of v4l2_info().
> ---
>  drivers/media/platform/rcar-vin/rcar-v4l2.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/rcar-vin/rcar-v4l2.c b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> index 457a65bf6b664f05..76f6f46799e95791 100644
> --- a/drivers/media/platform/rcar-vin/rcar-v4l2.c
> +++ b/drivers/media/platform/rcar-vin/rcar-v4l2.c
> @@ -969,9 +969,23 @@ void rvin_v4l2_unregister(struct rvin_dev *vin)
>  static void rvin_notify_video_device(struct rvin_dev *vin,
>  				     unsigned int notification, void *arg)
>  {
> +	const struct v4l2_event *event;
> +
>  	switch (notification) {
>  	case V4L2_DEVICE_NOTIFY_EVENT:
> -		v4l2_event_queue(&vin->vdev, arg);
> +		event = arg;
> +
> +		switch (event->type) {
> +		case V4L2_EVENT_EOS:

This is not the right event for this. EVENT_EOS is specific to codecs and does
not signal an error condition.

I think we need a new event for this, I've seen similar situations with HDMI
receivers. The SOURCE_CHANGE event was (ab)used for that, but I think a new
event (V4L2_EVENT_XFER_ERROR?) should be created for these situations.

> +			rvin_stop_streaming(vin);

In addition to this you should call vb2_queue_error(), that's typically used
in situations where there is an unrecoverable transfer error.

Regards,

	Hans

> +			vin_dbg(vin,
> +				"Subdevice signaled end of stream, stopping.\n");
> +			break;
> +		default:
> +			break;
> +		}
> +
> +		v4l2_event_queue(&vin->vdev, event);
>  		break;
>  	default:
>  		break;
>