Re: [PATCH 3/7] media: vimc: Create a V4L2 output device

[Helen Koike <helen.koike@collabora.com>]

Hi André,

Thanks for the patch, just some minor comments below.

On 7/2/19 12:47 PM, André Almeida wrote:
> Using the functions on vimc-video, create a V4L2 output device.
> When a streaming is initialized on the output device, it'll start
> returning those buffers on to the userspace, while always keeping one on
> the list. When the capture device starts streaming on the same pipeline,
> it will copy the first frame on the list to the process_frame pipeline.
> 
> The vimc-streamer has a callback to warn all subdevices when a streaming
> will start or stop. This is useful so the subdevices can allocate a
> frame with suitable size to send through the pipeline, and then free
> then when it not used anymore. Since the vimc-output will also be part
> of the pipeline (but it is not a V4L2 subdevice), change the callback to
> be part of vimc_ent_device, rather than a linked with the subdevice API.
> In this way, it's possible to have a generic solution to call start/stop
> streaming callbacks to all devices in the pipeline.
> 
> Add a vb2 buffer validate function. This is required to
> create a V4L2 output device.
> 
> Signed-off-by: André Almeida <andrealmeid@collabora.com>
> ---
>  drivers/media/platform/vimc/Makefile        |   4 +-
>  drivers/media/platform/vimc/vimc-common.h   |   5 +-
>  drivers/media/platform/vimc/vimc-debayer.c  |  11 +-
>  drivers/media/platform/vimc/vimc-output.c   | 362 ++++++++++++++++++++
>  drivers/media/platform/vimc/vimc-scaler.c   |  10 +-
>  drivers/media/platform/vimc/vimc-sensor.c   |  10 +-
>  drivers/media/platform/vimc/vimc-streamer.c |  22 +-
>  drivers/media/platform/vimc/vimc-video.c    |   9 +
>  drivers/media/platform/vimc/vimc-video.h    |   2 +
>  9 files changed, 395 insertions(+), 40 deletions(-)
>  create mode 100644 drivers/media/platform/vimc/vimc-output.c
> 
> diff --git a/drivers/media/platform/vimc/Makefile b/drivers/media/platform/vimc/Makefile
> index fb90aa0f33a5..611331b9fceb 100644
> --- a/drivers/media/platform/vimc/Makefile
> +++ b/drivers/media/platform/vimc/Makefile
> @@ -1,5 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
>  vimc-y := vimc-core.o vimc-common.o vimc-streamer.o
>  
> -obj-$(CONFIG_VIDEO_VIMC) += vimc.o vimc-video.o vimc-capture.o vimc-debayer.o \
> -                vimc-scaler.o vimc-sensor.o
> +obj-$(CONFIG_VIDEO_VIMC) += vimc.o vimc-video.o vimc-capture.o vimc-output.o \
> +                vimc-debayer.o vimc-scaler.o vimc-sensor.o
> diff --git a/drivers/media/platform/vimc/vimc-common.h b/drivers/media/platform/vimc/vimc-common.h
> index 7b4d988b208b..003024bcdaed 100644
> --- a/drivers/media/platform/vimc/vimc-common.h
> +++ b/drivers/media/platform/vimc/vimc-common.h
> @@ -78,6 +78,8 @@ struct vimc_platform_data {
>   * @vdev_get_format:	callback that returns the current format a pad, used
>   *			only when is_media_entity_v4l2_video_device(ent) returns
>   *			true
> + * @s_stream:		callback used when vimc-capture will start/stop a
> + *			streaming, to subdevice alloc/free it frames

I would re-word this a bit:
callback used when vimc-capture start/stop streaming, so subdevices can alloc/free frames.

>   *
>   * Each node of the topology must create a vimc_ent_device struct. Depending on
>   * the node it will be of an instance of v4l2_subdev or video_device struct
> @@ -94,7 +96,8 @@ struct vimc_ent_device {
>  	void * (*process_frame)(struct vimc_ent_device *ved,
>  				const void *frame);
>  	void (*vdev_get_format)(struct vimc_ent_device *ved,
> -			      struct v4l2_pix_format *fmt);
> +				struct v4l2_pix_format *fmt);
> +	int (*s_stream)(struct vimc_ent_device *ved, int enable);
>  };
>  
>  /**
> diff --git a/drivers/media/platform/vimc/vimc-debayer.c b/drivers/media/platform/vimc/vimc-debayer.c
> index 00598fbf3cba..9e0c7c2c3c72 100644
> --- a/drivers/media/platform/vimc/vimc-debayer.c
> +++ b/drivers/media/platform/vimc/vimc-debayer.c
> @@ -320,9 +320,10 @@ static void vimc_deb_set_rgb_pix_rgb24(struct vimc_deb_device *vdeb,
>  		vdeb->src_frame[index + i] = rgb[i];
>  }
>  
> -static int vimc_deb_s_stream(struct v4l2_subdev *sd, int enable)
> +static int vimc_deb_s_stream(struct vimc_ent_device *ved, int enable)
>  {
> -	struct vimc_deb_device *vdeb = v4l2_get_subdevdata(sd);
> +	struct vimc_deb_device *vdeb = container_of(ved, struct vimc_deb_device,
> +						    ved);
>  
>  	if (enable) {
>  		u32 src_pixelformat = vdeb->ved.stream->producer_pixfmt;
> @@ -373,13 +374,8 @@ static int vimc_deb_s_stream(struct v4l2_subdev *sd, int enable)
>  	return 0;
>  }
>  
> -static const struct v4l2_subdev_video_ops vimc_deb_video_ops = {
> -	.s_stream = vimc_deb_s_stream,
> -};
> -
>  static const struct v4l2_subdev_ops vimc_deb_ops = {
>  	.pad = &vimc_deb_pad_ops,
> -	.video = &vimc_deb_video_ops,
>  };
>  
>  static unsigned int vimc_deb_get_val(const u8 *bytes,
> @@ -549,6 +545,7 @@ static int vimc_deb_comp_bind(struct device *comp, struct device *master,
>  	}
>  
>  	vdeb->ved.process_frame = vimc_deb_process_frame;
> +	vdeb->ved.s_stream = vimc_deb_s_stream;
>  	dev_set_drvdata(comp, &vdeb->ved);
>  	vdeb->dev = comp;
>  
> diff --git a/drivers/media/platform/vimc/vimc-output.c b/drivers/media/platform/vimc/vimc-output.c
> new file mode 100644
> index 000000000000..3fb9441adc43
> --- /dev/null
> +++ b/drivers/media/platform/vimc/vimc-output.c
> @@ -0,0 +1,362 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * vimc-output.c Virtual Media Controller Driver
> + *
> + * Copyright 2019 Collabora, Ltd.
> + */
> +
> +#include "vimc-video.h"
> +#include <linux/kthread.h>
> +#include <linux/freezer.h>
> +
> +#define VIMC_OUT_DRV_NAME "vimc-output"
> +
> +static const struct v4l2_ioctl_ops vimc_out_ioctl_ops = {
> +	.vidioc_querycap = vimc_vid_querycap,
> +
> +	.vidioc_g_fmt_vid_out = vimc_vid_g_fmt,
> +	.vidioc_s_fmt_vid_out = vimc_vid_s_fmt,
> +	.vidioc_try_fmt_vid_out = vimc_vid_try_fmt,
> +	.vidioc_enum_fmt_vid_out = vimc_vid_enum_fmt,
> +	.vidioc_enum_framesizes = vimc_vid_enum_framesizes,
> +
> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
> +	.vidioc_querybuf = vb2_ioctl_querybuf,
> +	.vidioc_qbuf = vb2_ioctl_qbuf,
> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
> +	.vidioc_expbuf = vb2_ioctl_expbuf,
> +	.vidioc_streamon = vb2_ioctl_streamon,
> +	.vidioc_streamoff = vb2_ioctl_streamoff,
> +};
> +
> +/**
> + * vimc_out_consume_frame - grab a frame from the queue and release it
> + *
> + * @arg: *vimc_vid_device passed as argument to kthread
> + *
> + * This function is called when the stream is on. If there's a frame available

s/This function is called/This thread is started/

> + * on the queue, it will get it and "consume" it. This means, marks the frame
> + * as done and make sure there're at least one frame to be on the list.
> + * It should stop when the streaming stops too
> + *
> + * Return: always 0
> + */
> +static int vimc_out_consume_frame(void *arg)
> +{
> +	struct vimc_vid_device *vout = arg;
> +	struct vimc_vid_buffer *vimc_buf;
> +
> +	set_freezable();
> +
> +	for (;;) {
> +		try_to_freeze();
> +		if (kthread_should_stop())
> +			break;
> +
> +		/* TODO: support custom framerate */
> +		set_current_state(TASK_UNINTERRUPTIBLE);
> +		schedule_timeout(HZ / 60);
> +
> +		spin_lock(&vout->qlock);
> +
> +		/*
> +		 * if there's only on frame on the buffer, keep it there
> +		 * this is done in a way that the output always can send a
> +		 * frame to the pipeline, even if the capture framerate is
> +		 * higher than the output framarate

s/framarate/framerate/

> +		 */
> +		if (list_empty(&vout->buf_list) ||
> +		    list_is_singular(&vout->buf_list)) {
> +			spin_unlock(&vout->qlock);
> +			continue;
> +		}
> +
> +		vimc_buf = list_first_entry(&vout->buf_list,
> +				    typeof(*vimc_buf), list);
> +		list_del(&vimc_buf->list);
> +		spin_unlock(&vout->qlock);
> +
> +		vimc_buf->vb2.vb2_buf.timestamp = ktime_get_ns();
> +		vimc_buf->vb2.sequence = vout->sequence++;
> +		vimc_buf->vb2.field = vout->format.field;
> +		vb2_buffer_done(&vimc_buf->vb2.vb2_buf, VB2_BUF_STATE_DONE);
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * vimc_out_start_streaming - callback used when userspace starts streaming
> + *
> + * @vq:	   queue of vb2 video buffers
> + * @count: number of already queued buffers
> + *
> + * Allocate the output frame and starts the consume thread
> + *
> + * Return: 0 on success or error code
> + */
> +static int vimc_out_start_streaming(struct vb2_queue *vq, unsigned int count)
> +{
> +	struct vimc_vid_device *vout = vb2_get_drv_priv(vq);
> +
> +	vout->sequence = 0;
> +
> +	vout->kthread_fd = kthread_run(vimc_out_consume_frame, vout,
> +					      "vimc-output consume thread");

Alignment

> +
> +	if (IS_ERR(vout->kthread_fd))
> +		return PTR_ERR(vout->kthread_fd);
> +
> +	return 0;
> +}
> +
> +/**
> + * vimc_out_stop_streaming - callback used when userspace stops streaming
> + *
> + * @vq:	   queue of vb2 video buffers
> + *
> + * Wait until vimc_stream stops consuming a frame (using a mutex) and free it.
> + * Stops the thread and return all unused buffers to userspace.
> + */
> +static void vimc_out_stop_streaming(struct vb2_queue *vq)
> +{
> +	struct vimc_vid_device *vout = vb2_get_drv_priv(vq);
> +
> +	vout->sequence = 0;
> +
> +	kthread_stop(vout->kthread_fd);
> +
> +	vimc_vid_return_all_buffers(vout, VB2_BUF_STATE_ERROR);
> +}
> +
> +static const struct vb2_ops vimc_out_qops = {
> +	.start_streaming	= vimc_out_start_streaming,
> +	.stop_streaming		= vimc_out_stop_streaming,
> +	.buf_queue		= vimc_vid_buf_queue,
> +	.queue_setup		= vimc_vid_queue_setup,
> +	.buf_prepare		= vimc_vid_buffer_prepare,
> +	.buf_out_validate	= vimc_vid_buffer_validate,
> +	/*
> +	 * Since q->lock is set we can use the standard
> +	 * vb2_ops_wait_prepare/finish helper functions.
> +	 */
> +	.wait_prepare		= vb2_ops_wait_prepare,
> +	.wait_finish		= vb2_ops_wait_finish,
> +};
> +
> +static const struct media_entity_operations vimc_out_mops = {
> +	.link_validate		= vimc_link_validate,
> +};
> +
> +/**
> + * vimc_out_process_frame - process a frame on media pipeline
> + *
> + * @ved:   the vimc entity structure to process the frame
> + * @frame: pointer to the pipeline frame. Unused by output
> + *
> + * If there's a frame to be sent to the pipeline, copy the newest frame and
> + * send it through the pipeline.
> + * If there's no frame on vimc_output buffer list (this probably means that
> + * there's no streaming going on at the output) or the pixelformat of the stream
> + * mismatch the output format, send NULL.
> + */
> +static void *vimc_out_process_frame(struct vimc_ent_device *ved,
> +						 const void *frame)

Alignment

> +{
> +	struct vimc_vid_device *vout = container_of(ved, struct vimc_vid_device,
> +						    ved);
> +	struct vimc_vid_buffer *vimc_buf;
> +	void *vbuf;
> +
> +	if (ved->stream->producer_pixfmt != vout->format.pixelformat)
> +		return NULL;

fyi, after reverting "media: vimc: propagate pixel format in the stream"
this check should be done in vimc_link_validate

> +
> +	spin_lock(&vout->qlock);
> +	vimc_buf = list_first_entry_or_null(&vout->buf_list,
> +					    typeof(*vimc_buf), list);
> +	spin_unlock(&vout->qlock);
> +
> +	if (!vimc_buf)
> +		return NULL;
> +
> +	vbuf = vb2_plane_vaddr(&vimc_buf->vb2.vb2_buf, 0);
> +	memcpy(vout->frame, vbuf, vout->format.sizeimage);
> +
> +	return vout->frame;
> +}
> +
> +/**
> + * vimc_out_s_stream - callback before/after the start/stop of pipeline stream
> + *
> + * @ved:	the vimc_ent_device compenent of vimc_vid_device
> + * @enable:	0 means that the streaming has stop, non-zero means the
> + *		will begin

s/has/has to/
I think some word is missing. Maybe just:
0 stop the stream, non-zero start the stream

> + *
> + */
> +static int vimc_out_s_stream(struct vimc_ent_device *ved, int enable)
> +{
> +	struct vimc_vid_device *vout =
> +				container_of(ved, struct vimc_vid_device, ved);
> +
> +	if (enable) {
> +		vout->frame = vmalloc(vout->format.sizeimage);
> +		if (!vout->frame)
> +			return -ENOMEM;
> +
> +	} else {
> +		vfree(vout->frame);
> +		vout->frame = NULL;
> +	}
> +
> +	return 0;
> +}
> +
> +static int vimc_out_comp_bind(struct device *comp, struct device *master,
> +		void *master_data)
> +{
> +	struct v4l2_device *v4l2_dev = master_data;
> +	struct vimc_platform_data *pdata = comp->platform_data;
> +	struct vimc_vid_device *vout;
> +	struct video_device *vdev;
> +	struct vb2_queue *q;
> +	int ret;
> +
> +	/* Allocate the vimc_vid_device struct */
> +	vout = kzalloc(sizeof(*vout), GFP_KERNEL);
> +	if (!vout)
> +		return -ENOMEM;
> +
> +	vout->stream.pipe_size = 0;
> +	/* Allocate the pads */
> +	vout->ved.pads =
> +		vimc_pads_init(1, (const unsigned long[1]) {MEDIA_PAD_FL_SOURCE});
> +	if (IS_ERR(vout->ved.pads)) {
> +		ret = PTR_ERR(vout->ved.pads);
> +		goto err_free_vout;
> +	}
> +
> +	/* Initialize the media entity */
> +	vout->vdev.entity.name = pdata->entity_name;
> +	vout->vdev.entity.function = MEDIA_ENT_F_IO_V4L;
> +	ret = media_entity_pads_init(&vout->vdev.entity,
> +				     1, vout->ved.pads);
> +	if (ret)
> +		goto err_clean_pads;
> +
> +	/* Initialize the lock */
> +	mutex_init(&vout->lock);
> +
> +	/* Initialize the vb2 queue */
> +	q = &vout->queue;
> +	q->type = V4L2_BUF_TYPE_VIDEO_OUTPUT;
> +	q->io_modes = VB2_MMAP | VB2_DMABUF | VB2_USERPTR;
> +	q->drv_priv = vout;
> +	q->buf_struct_size = sizeof(struct vimc_vid_buffer);
> +	q->ops = &vimc_out_qops;
> +	q->mem_ops = &vb2_vmalloc_memops;
> +	q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
> +	q->min_buffers_needed = 2;
> +	q->lock = &vout->lock;
> +
> +	ret = vb2_queue_init(q);
> +	if (ret) {
> +		dev_err(comp, "%s: vb2 queue init failed (err=%d)\n",
> +				pdata->entity_name, ret);

alignment

> +		goto err_clean_m_ent;
> +	}
> +
> +	/* Initialize buffer list and its lock */
> +	INIT_LIST_HEAD(&vout->buf_list);
> +	spin_lock_init(&vout->qlock);
> +
> +	/* Set default frame format */
> +	vout->format = fmt_default;
> +	v4l2_fill_pixfmt(&vout->format, vout->format.pixelformat,
> +			 vout->format.width, vout->format.height);
> +
> +	/* Fill the vimc_ent_device struct */
> +	vout->ved.ent = &vout->vdev.entity;
> +	vout->ved.process_frame = vimc_out_process_frame;
> +	vout->ved.s_stream = vimc_out_s_stream;
> +	vout->ved.vdev_get_format = vimc_vid_get_format;
> +	dev_set_drvdata(comp, &vout->ved);
> +	vout->dev = comp;
> +
> +	/* Initialize the video_device struct */
> +	vdev = &vout->vdev;
> +	vdev->device_caps = V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_STREAMING;
> +	vdev->entity.ops = &vimc_out_mops;
> +	vdev->release = vimc_vid_release;
> +	vdev->fops = &vimc_vid_fops;
> +	vdev->ioctl_ops = &vimc_out_ioctl_ops;
> +	vdev->lock = &vout->lock;
> +	vdev->queue = q;
> +	vdev->v4l2_dev = v4l2_dev;
> +	vdev->vfl_dir = VFL_DIR_TX;
> +	strscpy(vdev->name, pdata->entity_name, sizeof(vdev->name));
> +	video_set_drvdata(vdev, &vout->ved);
> +
> +	/* Register the video_device with the v4l2 and the media framework */
> +	ret = video_register_device(vdev, VFL_TYPE_GRABBER, -1);
> +	if (ret) {
> +		dev_err(comp, "%s: video register failed (err=%d)\n",
> +				vout->vdev.name, ret);
> +		goto err_release_queue;
> +	}
> +
> +	return 0;
> +
> +err_release_queue:
> +	vb2_queue_release(q);
> +err_clean_m_ent:
> +	media_entity_cleanup(&vout->vdev.entity);
> +err_clean_pads:
> +	vimc_pads_cleanup(vout->ved.pads);
> +err_free_vout:
> +	kfree(vout);
> +
> +	return ret;
> +}
> +
> +static const struct component_ops vimc_out_comp_ops = {
> +	.bind = vimc_out_comp_bind,
> +	.unbind = vimc_vid_comp_unbind,
> +};
> +
> +static int vimc_out_probe(struct platform_device *pdev)
> +{
> +	return component_add(&pdev->dev, &vimc_out_comp_ops);
> +}
> +
> +static int vimc_out_remove(struct platform_device *pdev)
> +{
> +	component_del(&pdev->dev, &vimc_out_comp_ops);
> +
> +	return 0;
> +}
> +
> +static const struct platform_device_id vimc_out_driver_ids[] = {
> +	{
> +		.name           = VIMC_OUT_DRV_NAME,
> +	},
> +	{ }
> +};
> +
> +static struct platform_driver vimc_out_pdrv = {
> +	.probe		= vimc_out_probe,
> +	.remove		= vimc_out_remove,
> +	.id_table	= vimc_out_driver_ids,
> +	.driver		= {
> +		.name	= VIMC_OUT_DRV_NAME,
> +	},
> +};
> +
> +module_platform_driver(vimc_out_pdrv);
> +
> +MODULE_DEVICE_TABLE(platform, vimc_out_driver_ids);
> +
> +MODULE_DESCRIPTION("Virtual Media Controller Driver (VIMC) Output");
> +MODULE_AUTHOR("André Almeida <andrealmeid@collabora.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/media/platform/vimc/vimc-scaler.c b/drivers/media/platform/vimc/vimc-scaler.c
> index c7123a45c55b..2c3e486a29c0 100644
> --- a/drivers/media/platform/vimc/vimc-scaler.c
> +++ b/drivers/media/platform/vimc/vimc-scaler.c
> @@ -194,9 +194,10 @@ static const struct v4l2_subdev_pad_ops vimc_sca_pad_ops = {
>  	.set_fmt		= vimc_sca_set_fmt,
>  };
>  
> -static int vimc_sca_s_stream(struct v4l2_subdev *sd, int enable)
> +static int vimc_sca_s_stream(struct vimc_ent_device *ved, int enable)
>  {
> -	struct vimc_sca_device *vsca = v4l2_get_subdevdata(sd);
> +	struct vimc_sca_device *vsca = container_of(ved, struct vimc_sca_device,
> +						    ved);
>  
>  	if (enable) {
>  		u32 pixelformat = vsca->ved.stream->producer_pixfmt;
> @@ -239,13 +240,9 @@ static int vimc_sca_s_stream(struct v4l2_subdev *sd, int enable)
>  	return 0;
>  }
>  
> -static const struct v4l2_subdev_video_ops vimc_sca_video_ops = {
> -	.s_stream = vimc_sca_s_stream,
> -};
>  
>  static const struct v4l2_subdev_ops vimc_sca_ops = {
>  	.pad = &vimc_sca_pad_ops,
> -	.video = &vimc_sca_video_ops,
>  };
>  
>  static void vimc_sca_fill_pix(u8 *const ptr,
> @@ -381,6 +378,7 @@ static int vimc_sca_comp_bind(struct device *comp, struct device *master,
>  	}
>  
>  	vsca->ved.process_frame = vimc_sca_process_frame;
> +	vsca->ved.s_stream = vimc_sca_s_stream,
>  	dev_set_drvdata(comp, &vsca->ved);
>  	vsca->dev = comp;
>  
> diff --git a/drivers/media/platform/vimc/vimc-sensor.c b/drivers/media/platform/vimc/vimc-sensor.c
> index 51359472eef2..a1afb840493d 100644
> --- a/drivers/media/platform/vimc/vimc-sensor.c
> +++ b/drivers/media/platform/vimc/vimc-sensor.c
> @@ -177,10 +177,10 @@ static void *vimc_sen_process_frame(struct vimc_ent_device *ved,
>  	return vsen->frame;
>  }
>  
> -static int vimc_sen_s_stream(struct v4l2_subdev *sd, int enable)
> +static int vimc_sen_s_stream(struct vimc_ent_device *ved, int enable)
>  {
>  	struct vimc_sen_device *vsen =
> -				container_of(sd, struct vimc_sen_device, sd);
> +				container_of(ved, struct vimc_sen_device, ved);
>  
>  	if (enable) {
>  		u32 pixelformat = vsen->ved.stream->producer_pixfmt;
> @@ -218,14 +218,9 @@ static const struct v4l2_subdev_core_ops vimc_sen_core_ops = {
>  	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
>  };
>  
> -static const struct v4l2_subdev_video_ops vimc_sen_video_ops = {
> -	.s_stream = vimc_sen_s_stream,
> -};
> -
>  static const struct v4l2_subdev_ops vimc_sen_ops = {
>  	.core = &vimc_sen_core_ops,
>  	.pad = &vimc_sen_pad_ops,
> -	.video = &vimc_sen_video_ops,
>  };
>  
>  static int vimc_sen_s_ctrl(struct v4l2_ctrl *ctrl)
> @@ -351,6 +346,7 @@ static int vimc_sen_comp_bind(struct device *comp, struct device *master,
>  		goto err_free_hdl;
>  
>  	vsen->ved.process_frame = vimc_sen_process_frame;
> +	vsen->ved.s_stream = vimc_sen_s_stream;
>  	dev_set_drvdata(comp, &vsen->ved);
>  	vsen->dev = comp;
>  
> diff --git a/drivers/media/platform/vimc/vimc-streamer.c b/drivers/media/platform/vimc/vimc-streamer.c
> index 3b3f36357a0e..fd330415ac38 100644
> --- a/drivers/media/platform/vimc/vimc-streamer.c
> +++ b/drivers/media/platform/vimc/vimc-streamer.c
> @@ -47,7 +47,6 @@ static struct media_entity *vimc_get_source_entity(struct media_entity *ent)
>  static void vimc_streamer_pipeline_terminate(struct vimc_stream *stream)
>  {
>  	struct vimc_ent_device *ved;
> -	struct v4l2_subdev *sd;
>  
>  	while (stream->pipe_size) {
>  		stream->pipe_size--;
> @@ -55,11 +54,8 @@ static void vimc_streamer_pipeline_terminate(struct vimc_stream *stream)
>  		ved->stream = NULL;
>  		stream->ved_pipeline[stream->pipe_size] = NULL;
>  
> -		if (!is_media_entity_v4l2_subdev(ved->ent))
> -			continue;
> -
> -		sd = media_entity_to_v4l2_subdev(ved->ent);
> -		v4l2_subdev_call(sd, video, s_stream, 0);
> +		if (ved->s_stream)
> +			ved->s_stream(ved, 0);
>  	}
>  }
>  
> @@ -79,7 +75,6 @@ static int vimc_streamer_pipeline_init(struct vimc_stream *stream,
>  	struct media_entity *entity;
>  	struct video_device *vdev;
>  	struct v4l2_subdev *sd;
> -	int ret = 0;
>  
>  	stream->pipe_size = 0;
>  	while (stream->pipe_size < VIMC_STREAMER_PIPELINE_MAX_SIZE) {
> @@ -90,16 +85,8 @@ static int vimc_streamer_pipeline_init(struct vimc_stream *stream,
>  		stream->ved_pipeline[stream->pipe_size++] = ved;
>  		ved->stream = stream;
>  
> -		if (is_media_entity_v4l2_subdev(ved->ent)) {
> -			sd = media_entity_to_v4l2_subdev(ved->ent);
> -			ret = v4l2_subdev_call(sd, video, s_stream, 1);
> -			if (ret && ret != -ENOIOCTLCMD) {
> -				pr_err("subdev_call error %s\n",
> -				       ved->ent->name);
> -				vimc_streamer_pipeline_terminate(stream);
> -				return ret;
> -			}
> -		}
> +		if (ved->s_stream)
> +			ved->s_stream(ved, 1);
>  
>  		entity = vimc_get_source_entity(ved->ent);
>  		/* Check if the end of the pipeline was reached*/
> @@ -149,6 +136,7 @@ static int vimc_streamer_thread(void *data)
>  			if (!frame || IS_ERR(frame))
>  				break;
>  		}
> +
>  		//wait for 60hz
>  		set_current_state(TASK_UNINTERRUPTIBLE);
>  		schedule_timeout(HZ / 60);
> diff --git a/drivers/media/platform/vimc/vimc-video.c b/drivers/media/platform/vimc/vimc-video.c
> index f7ccb2e9d6c5..0187e699543a 100644
> --- a/drivers/media/platform/vimc/vimc-video.c
> +++ b/drivers/media/platform/vimc/vimc-video.c
> @@ -236,6 +236,15 @@ int vimc_vid_buffer_prepare(struct vb2_buffer *vb)
>  }
>  EXPORT_SYMBOL_GPL(vimc_vid_buffer_prepare);
>  
> +int vimc_vid_buffer_validate(struct vb2_buffer *vb)
> +{
> +	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
> +
> +	vbuf->field = V4L2_FIELD_NONE;
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(vimc_vid_buffer_validate);

Is this function only used by the output? Maybe just keep it private in the output.

> +
>  void vimc_vid_release(struct video_device *vdev)
>  {
>  	struct vimc_vid_device *vid =
> diff --git a/drivers/media/platform/vimc/vimc-video.h b/drivers/media/platform/vimc/vimc-video.h
> index 22cb0e2dbdbb..67f13244bf92 100644
> --- a/drivers/media/platform/vimc/vimc-video.h
> +++ b/drivers/media/platform/vimc/vimc-video.h
> @@ -116,6 +116,8 @@ int vimc_vid_queue_setup(struct vb2_queue *vq, unsigned int *nbuffers,
>  
>  int vimc_vid_buffer_prepare(struct vb2_buffer *vb);
>  
> +int vimc_vid_buffer_validate(struct vb2_buffer *vb);
> +
>  int vimc_vid_probe(struct platform_device *pdev);
>  
>  int vimc_vid_remove(struct platform_device *pdev);
> 

Thanks,
Helen