Re: [PATCH v3 4/4] media: camss: sm8250: Pipeline starting and stopping for multiple virtual channels

[Robert Foss <robert.foss@linaro.org>]

On Fri, 7 Oct 2022 at 15:20, <quic_mmitkov@quicinc.com> wrote:
>
> From: Milen Mitkov <quic_mmitkov@quicinc.com>
>
> Use the multistream series function video_device_pipeline_alloc_start
> to allows multiple clients of the same pipeline.
>
> If any of the entities in the pipeline doesn't return success at stop
> (e.g. if a VFE line remains running), the full pipeline won't be stopped.
> This allows for stopping and starting streams at any point without
> disrupting the other running streams.
>
> Signed-off-by: Milen Mitkov <quic_mmitkov@quicinc.com>
> ---
>  .../media/platform/qcom/camss/camss-video.c   | 21 ++++++++++++++++---
>  1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/platform/qcom/camss/camss-video.c b/drivers/media/platform/qcom/camss/camss-video.c
> index 81fb3a5bc1d5..b042faf3dcda 100644
> --- a/drivers/media/platform/qcom/camss/camss-video.c
> +++ b/drivers/media/platform/qcom/camss/camss-video.c
> @@ -353,6 +353,7 @@ static int video_get_subdev_format(struct camss_video *video,
>
>         fmt.pad = pad;
>         fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
> +       fmt.stream = 0;
>
>         ret = v4l2_subdev_call(subdev, pad, get_fmt, NULL, &fmt);
>         if (ret)
> @@ -493,9 +494,11 @@ static int video_start_streaming(struct vb2_queue *q, unsigned int count)
>         struct v4l2_subdev *subdev;
>         int ret;
>
> -       ret = video_device_pipeline_start(vdev, &video->pipe);
> -       if (ret < 0)
> +       ret = video_device_pipeline_alloc_start(vdev);
> +       if (ret < 0) {
> +               dev_err(video->camss->dev, "Failed to start media pipeline: %d\n", ret);
>                 return ret;
> +       }
>
>         ret = video_check_format(video);
>         if (ret < 0)
> @@ -536,6 +539,7 @@ static void video_stop_streaming(struct vb2_queue *q)
>         struct media_entity *entity;
>         struct media_pad *pad;
>         struct v4l2_subdev *subdev;
> +       int ret;
>
>         entity = &vdev->entity;
>         while (1) {
> @@ -550,7 +554,18 @@ static void video_stop_streaming(struct vb2_queue *q)
>                 entity = pad->entity;
>                 subdev = media_entity_to_v4l2_subdev(entity);
>
> -               v4l2_subdev_call(subdev, video, s_stream, 0);
> +               ret = v4l2_subdev_call(subdev, video, s_stream, 0);
> +
> +               if (ret == -EBUSY) {
> +                       /* Don't stop if other instances of the pipeline are still running */
> +                       dev_dbg(video->camss->dev, "Video pipeline still used, don't stop streaming.\n");
> +                       return;
> +               }
> +
> +               if (ret) {
> +                       dev_err(video->camss->dev, "Video pipeline stop failed: %d\n", ret);
> +                       return;
> +               }
>         }
>
>         video_device_pipeline_stop(vdev);
> --
> 2.37.3
>

Reviewed-by: Robert Foss <robert.foss@linaro.org>