Re: [PATCH v4 2/2] media: platform: Add Aspeed Video Engine driver

[Eddie James <eajames@linux.vnet.ibm.com>]

On 10/12/2018 07:22 AM, Hans Verkuil wrote:
> On 10/05/2018 09:57 PM, Eddie James wrote:
>> The Video Engine (VE) embedded in the Aspeed AST2400 and AST2500 SOCs
>> can capture and compress video data from digital or analog sources. With
>> the Aspeed chip acting a service processor, the Video Engine can capture
>> the host processor graphics output.
>>
>> Add a V4L2 driver to capture video data and compress it to JPEG images.
>> Make the video frames available through the V4L2 streaming interface.
>>
>> Signed-off-by: Eddie James <eajames@linux.ibm.com>
>> ---
>>   MAINTAINERS                           |    8 +
>>   drivers/media/platform/Kconfig        |    8 +
>>   drivers/media/platform/Makefile       |    1 +
>>   drivers/media/platform/aspeed-video.c | 1674 +++++++++++++++++++++++++++++++++
>>   4 files changed, 1691 insertions(+)
>>   create mode 100644 drivers/media/platform/aspeed-video.c
>>
> <snip>
>
>> +static int aspeed_video_enum_input(struct file *file, void *fh,
>> +				   struct v4l2_input *inp)
>> +{
>> +	if (inp->index)
>> +		return -EINVAL;
>> +
>> +	strscpy(inp->name, "Host VGA capture", sizeof(inp->name));
>> +	inp->type = V4L2_INPUT_TYPE_CAMERA;
>> +	inp->capabilities = V4L2_IN_CAP_DV_TIMINGS;
>> +	inp->status = V4L2_IN_ST_NO_SIGNAL | V4L2_IN_ST_NO_SYNC;
> This can't be right. If there is a valid signal, then status should be 0.
> And ideally you can tell the difference between no signal and no sync
> as well.

Ah, yes I misunderstood the status, thanks.

>
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_get_input(struct file *file, void *fh, unsigned int *i)
>> +{
>> +	*i = 0;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_set_input(struct file *file, void *fh, unsigned int i)
>> +{
>> +	if (i)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_get_parm(struct file *file, void *fh,
>> +				 struct v4l2_streamparm *a)
>> +{
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	a->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
>> +	a->parm.capture.readbuffers = 3;
>> +	a->parm.capture.timeperframe.numerator = 1;
>> +	if (!video->frame_rate)
>> +		a->parm.capture.timeperframe.denominator = MAX_FRAME_RATE + 1;
>> +	else
>> +		a->parm.capture.timeperframe.denominator = video->frame_rate;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_set_parm(struct file *file, void *fh,
>> +				 struct v4l2_streamparm *a)
>> +{
>> +	unsigned int frame_rate = 0;
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	a->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
>> +	a->parm.capture.readbuffers = 3;
>> +
>> +	if (a->parm.capture.timeperframe.numerator)
>> +		frame_rate = a->parm.capture.timeperframe.denominator /
>> +			a->parm.capture.timeperframe.numerator;
>> +
>> +	if (!frame_rate || frame_rate > MAX_FRAME_RATE) {
>> +		frame_rate = 0;
>> +
>> +		/*
>> +		 * Set to max + 1 to differentiate between max and 0, which
>> +		 * means "don't care".
> But what does "don't care" mean in practice? It's still not clear to me how this
> is supposed to work.
>
>> +		 */
>> +		a->parm.capture.timeperframe.denominator = MAX_FRAME_RATE + 1;
> And regardless of anything else this timeperframe is out of the range that
> aspeed_video_enum_frameintervals() returns.
>
>> +		a->parm.capture.timeperframe.numerator = 1;
>> +	}
>> +
>> +	if (video->frame_rate != frame_rate) {
>> +		video->frame_rate = frame_rate;
>> +		aspeed_video_update(video, VE_CTRL, VE_CTRL_FRC,
>> +				    FIELD_PREP(VE_CTRL_FRC, frame_rate));
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_enum_framesizes(struct file *file, void *fh,
>> +					struct v4l2_frmsizeenum *fsize)
>> +{
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	if (fsize->index)
>> +		return -EINVAL;
>> +
>> +	if (fsize->pixel_format != V4L2_PIX_FMT_JPEG)
>> +		return -EINVAL;
>> +
>> +	fsize->discrete.width = video->pix_fmt.width;
>> +	fsize->discrete.height = video->pix_fmt.height;
>> +	fsize->type = V4L2_FRMSIZE_TYPE_DISCRETE;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_enum_frameintervals(struct file *file, void *fh,
>> +					    struct v4l2_frmivalenum *fival)
>> +{
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	if (fival->index)
>> +		return -EINVAL;
>> +
>> +	if (fival->width != video->width || fival->height != video->height)
>> +		return -EINVAL;
>> +
>> +	if (fival->pixel_format != V4L2_PIX_FMT_JPEG)
>> +		return -EINVAL;
>> +
>> +	fival->type = V4L2_FRMIVAL_TYPE_CONTINUOUS;
>> +
>> +	fival->stepwise.min.denominator = MAX_FRAME_RATE;
>> +	fival->stepwise.min.numerator = 1;
>> +	fival->stepwise.max.denominator = 1;
>> +	fival->stepwise.max.numerator = 1;
>> +	fival->stepwise.step = fival->stepwise.max;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_set_dv_timings(struct file *file, void *fh,
>> +				       struct v4l2_dv_timings *timings)
>> +{
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
> If vb2_is_busy() returns true, then return -EBUSY here. It is not allowed to
> set the timings while vb2 is busy.
>
>> +	if (video->width != timings->bt.width ||
>> +	    video->height != timings->bt.height)
>> +		return -EINVAL;
>> +
>> +	video->pix_fmt.width = timings->bt.width;
>> +	video->pix_fmt.height = timings->bt.height;
>> +	video->pix_fmt.sizeimage = video->max_compressed_size;
>> +	video->timings.width = timings->bt.width;
>> +	video->timings.height = timings->bt.height;
>> +
>> +	timings->type = V4L2_DV_BT_656_1120;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_get_dv_timings(struct file *file, void *fh,
>> +				       struct v4l2_dv_timings *timings)
>> +{
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	timings->type = V4L2_DV_BT_656_1120;
>> +	timings->bt = video->timings;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_query_dv_timings(struct file *file, void *fh,
>> +					 struct v4l2_dv_timings *timings)
>> +{
>> +	int rc;
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	if (file->f_flags & O_NONBLOCK) {
>> +		if (test_bit(VIDEO_RES_CHANGE, &video->flags))
>> +			return -EAGAIN;
>> +	} else {
>> +		rc = wait_event_interruptible(video->wait,
>> +					      !test_bit(VIDEO_RES_CHANGE,
>> +							&video->flags));
>> +		if (rc)
>> +			return -EINTR;
>> +	}
>> +
>> +	timings->type = V4L2_DV_BT_656_1120;
>> +	timings->bt = video->timings;
>> +	timings->bt.width = video->width;
>> +	timings->bt.height = video->height;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_enum_dv_timings(struct file *file, void *fh,
>> +					struct v4l2_enum_dv_timings *timings)
>> +{
>> +	if (timings->index)
>> +		return -EINVAL;
>> +
>> +	return aspeed_video_get_dv_timings(file, fh, &timings->timings);
>> +}
>> +
>> +static int aspeed_video_dv_timings_cap(struct file *file, void *fh,
>> +				       struct v4l2_dv_timings_cap *cap)
>> +{
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	cap->type = V4L2_DV_BT_656_1120;
>> +	cap->bt.capabilities = V4L2_DV_BT_CAP_PROGRESSIVE;
>> +	cap->bt.min_width = video->width;
>> +	cap->bt.max_width = video->width;
>> +	cap->bt.min_height = video->height;
>> +	cap->bt.max_height = video->height;
> This should return the capabilities of the aspeed. In this case I'd
> guess that the max width/height is 1920x1080 (or perhaps 1200).
>
> The minimum is probably the VGA resolution.

OK that works, but keep in mind a call to s_dv_timings must return 
EINVAL if the timings resolution doesn't match the detected 
resolution... driver can't change the capture resolution.

>
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_sub_event(struct v4l2_fh *fh,
>> +				  const struct v4l2_event_subscription *sub)
>> +{
>> +	switch (sub->type) {
>> +	case V4L2_EVENT_SOURCE_CHANGE:
>> +		return v4l2_src_change_event_subscribe(fh, sub);
>> +	}
>> +
>> +	return v4l2_ctrl_subscribe_event(fh, sub);
>> +}
>> +
>> +static const struct v4l2_ioctl_ops aspeed_video_ioctl_ops = {
>> +	.vidioc_querycap = aspeed_video_querycap,
>> +
>> +	.vidioc_enum_fmt_vid_cap = aspeed_video_enum_format,
>> +	.vidioc_g_fmt_vid_cap = aspeed_video_get_format,
>> +	.vidioc_s_fmt_vid_cap = aspeed_video_get_format,
>> +	.vidioc_try_fmt_vid_cap = aspeed_video_get_format,
>> +
>> +	.vidioc_reqbufs = vb2_ioctl_reqbufs,
>> +	.vidioc_querybuf = vb2_ioctl_querybuf,
>> +	.vidioc_qbuf = vb2_ioctl_qbuf,
>> +	.vidioc_dqbuf = vb2_ioctl_dqbuf,
>> +	.vidioc_create_bufs = vb2_ioctl_create_bufs,
>> +	.vidioc_prepare_buf = vb2_ioctl_prepare_buf,
>> +	.vidioc_streamon = vb2_ioctl_streamon,
>> +	.vidioc_streamoff = vb2_ioctl_streamoff,
>> +
>> +	.vidioc_enum_input = aspeed_video_enum_input,
>> +	.vidioc_g_input = aspeed_video_get_input,
>> +	.vidioc_s_input = aspeed_video_set_input,
>> +
>> +	.vidioc_g_parm = aspeed_video_get_parm,
>> +	.vidioc_s_parm = aspeed_video_set_parm,
>> +	.vidioc_enum_framesizes = aspeed_video_enum_framesizes,
>> +	.vidioc_enum_frameintervals = aspeed_video_enum_frameintervals,
>> +
>> +	.vidioc_s_dv_timings = aspeed_video_set_dv_timings,
>> +	.vidioc_g_dv_timings = aspeed_video_get_dv_timings,
>> +	.vidioc_query_dv_timings = aspeed_video_query_dv_timings,
>> +	.vidioc_enum_dv_timings = aspeed_video_enum_dv_timings,
>> +	.vidioc_dv_timings_cap = aspeed_video_dv_timings_cap,
>> +
>> +	.vidioc_subscribe_event = aspeed_video_sub_event,
>> +	.vidioc_unsubscribe_event = v4l2_event_unsubscribe,
>> +};
>> +
>> +static void aspeed_video_update_jpeg_quality(struct aspeed_video *video)
>> +{
>> +	u32 comp_ctrl = FIELD_PREP(VE_COMP_CTRL_DCT_LUM, video->jpeg_quality) |
>> +		FIELD_PREP(VE_COMP_CTRL_DCT_CHR, video->jpeg_quality | 0x10);
>> +
>> +	aspeed_video_update(video, VE_COMP_CTRL,
>> +			    VE_COMP_CTRL_DCT_LUM | VE_COMP_CTRL_DCT_CHR,
>> +			    comp_ctrl);
>> +}
>> +
>> +static void aspeed_video_update_subsampling(struct aspeed_video *video)
>> +{
>> +	if (video->jpeg.virt)
>> +		aspeed_video_init_jpeg_table(video->jpeg.virt, video->yuv420);
>> +
>> +	if (video->yuv420)
>> +		aspeed_video_update(video, VE_SEQ_CTRL, 0, VE_SEQ_CTRL_YUV420);
>> +	else
>> +		aspeed_video_update(video, VE_SEQ_CTRL, VE_SEQ_CTRL_YUV420, 0);
>> +}
>> +
>> +static int aspeed_video_set_ctrl(struct v4l2_ctrl *ctrl)
>> +{
>> +	struct aspeed_video *video = container_of(ctrl->handler,
>> +						  struct aspeed_video,
>> +						  ctrl_handler);
>> +
>> +	switch (ctrl->id) {
>> +	case V4L2_CID_JPEG_COMPRESSION_QUALITY:
>> +		video->jpeg_quality = ctrl->val;
>> +		aspeed_video_update_jpeg_quality(video);
>> +		break;
>> +	case V4L2_CID_JPEG_CHROMA_SUBSAMPLING:
>> +		if (ctrl->val == V4L2_JPEG_CHROMA_SUBSAMPLING_420) {
>> +			video->yuv420 = true;
>> +			aspeed_video_update_subsampling(video);
>> +		} else {
>> +			video->yuv420 = false;
>> +			aspeed_video_update_subsampling(video);
>> +		}
>> +		break;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct v4l2_ctrl_ops aspeed_video_ctrl_ops = {
>> +	.s_ctrl = aspeed_video_set_ctrl,
>> +};
>> +
>> +static void aspeed_video_resolution_work(struct work_struct *work)
>> +{
>> +	int rc;
>> +	struct delayed_work *dwork = to_delayed_work(work);
>> +	struct aspeed_video *video = container_of(dwork, struct aspeed_video,
>> +						  res_work);
>> +
>> +	/* No clients remaining after delay */
>> +	if (atomic_read(&video->clients) == 0)
>> +		goto done;
>> +
>> +	aspeed_video_on(video);
>> +
>> +	aspeed_video_init_regs(video);
>> +
>> +	rc = aspeed_video_get_resolution(video);
>> +	if (rc)
>> +		dev_err(video->dev,
>> +			"resolution changed; couldn't get new resolution\n");
>> +	else if (test_bit(VIDEO_STREAMING, &video->flags))
>> +		aspeed_video_start_frame(video);
>> +
>> +	if (video->width != video->pix_fmt.width ||
>> +	    video->height != video->pix_fmt.height) {
>> +		static const struct v4l2_event ev = {
>> +			.type = V4L2_EVENT_SOURCE_CHANGE,
>> +			.u.src_change.changes = V4L2_EVENT_SRC_CH_RESOLUTION,
>> +		};
>> +
>> +		v4l2_event_queue(&video->vdev, &ev);
>> +	}
>> +
>> +done:
>> +	clear_bit(VIDEO_RES_CHANGE, &video->flags);
>> +	wake_up_interruptible_all(&video->wait);
>> +}
>> +
>> +static int aspeed_video_open(struct file *file)
>> +{
>> +	int rc;
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	mutex_lock(&video->video_lock);
>> +
>> +	if (atomic_inc_return(&video->clients) == 1) {
>> +		rc = aspeed_video_start(video);
>> +		if (rc) {
>> +			dev_err(video->dev, "Failed to start video engine\n");
>> +			atomic_dec(&video->clients);
>> +			mutex_unlock(&video->video_lock);
>> +			return rc;
>> +		}
>> +	}
>> +
>> +	mutex_unlock(&video->video_lock);
>> +
>> +	return v4l2_fh_open(file);
>> +}
>> +
>> +static int aspeed_video_release(struct file *file)
>> +{
>> +	int rc;
>> +	struct aspeed_video *video = video_drvdata(file);
>> +
>> +	rc = vb2_fop_release(file);
>> +
>> +	mutex_lock(&video->video_lock);
>> +
>> +	if (atomic_dec_return(&video->clients) == 0)
>> +		aspeed_video_stop(video);
>> +
>> +	mutex_unlock(&video->video_lock);
>> +
>> +	return rc;
>> +}
>> +
>> +static const struct v4l2_file_operations aspeed_video_v4l2_fops = {
>> +	.owner = THIS_MODULE,
>> +	.read = vb2_fop_read,
>> +	.poll = vb2_fop_poll,
>> +	.unlocked_ioctl = video_ioctl2,
>> +	.mmap = vb2_fop_mmap,
>> +	.open = aspeed_video_open,
>> +	.release = aspeed_video_release,
>> +};
>> +
>> +static int aspeed_video_queue_setup(struct vb2_queue *q,
>> +				    unsigned int *num_buffers,
>> +				    unsigned int *num_planes,
>> +				    unsigned int sizes[],
>> +				    struct device *alloc_devs[])
>> +{
>> +	struct aspeed_video *video = vb2_get_drv_priv(q);
>> +
>> +	if (*num_planes) {
>> +		if (sizes[0] < video->max_compressed_size)
>> +			return -EINVAL;
>> +
>> +		return 0;
>> +	}
>> +
>> +	*num_planes = 1;
>> +	sizes[0] = video->max_compressed_size;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_buf_prepare(struct vb2_buffer *vb)
>> +{
>> +	struct aspeed_video *video = vb2_get_drv_priv(vb->vb2_queue);
>> +
>> +	if (vb2_plane_size(vb, 0) < video->max_compressed_size)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_start_streaming(struct vb2_queue *q,
>> +					unsigned int count)
>> +{
>> +	int rc;
>> +	struct aspeed_video *video = vb2_get_drv_priv(q);
>> +
>> +	rc = aspeed_video_start_frame(video);
>> +	if (rc) {
>> +		aspeed_video_bufs_done(video, VB2_BUF_STATE_QUEUED);
>> +		return rc;
>> +	}
>> +
>> +	video->sequence = 0;
>> +	set_bit(VIDEO_STREAMING, &video->flags);
>> +	return 0;
>> +}
>> +
>> +static void aspeed_video_stop_streaming(struct vb2_queue *q)
>> +{
>> +	int rc;
>> +	struct aspeed_video *video = vb2_get_drv_priv(q);
>> +
>> +	clear_bit(VIDEO_STREAMING, &video->flags);
>> +
>> +	rc = wait_event_timeout(video->wait,
>> +				!test_bit(VIDEO_FRAME_INPRG, &video->flags),
>> +				STOP_TIMEOUT);
>> +	if (!rc) {
>> +		dev_err(video->dev, "Timed out when stopping streaming\n");
>> +		aspeed_video_stop(video);
>> +	}
>> +
>> +	aspeed_video_bufs_done(video, VB2_BUF_STATE_ERROR);
>> +}
>> +
>> +static void aspeed_video_buf_queue(struct vb2_buffer *vb)
>> +{
>> +	struct aspeed_video *video = vb2_get_drv_priv(vb->vb2_queue);
>> +	struct vb2_v4l2_buffer *vbuf = to_vb2_v4l2_buffer(vb);
>> +	struct aspeed_video_buffer *avb = to_aspeed_video_buffer(vbuf);
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&video->lock, flags);
>> +	list_add_tail(&avb->link, &video->buffers);
>> +	spin_unlock_irqrestore(&video->lock, flags);
>> +}
>> +
>> +static const struct vb2_ops aspeed_video_vb2_ops = {
>> +	.queue_setup = aspeed_video_queue_setup,
>> +	.wait_prepare = vb2_ops_wait_prepare,
>> +	.wait_finish = vb2_ops_wait_finish,
>> +	.buf_prepare = aspeed_video_buf_prepare,
>> +	.start_streaming = aspeed_video_start_streaming,
>> +	.stop_streaming = aspeed_video_stop_streaming,
>> +	.buf_queue =  aspeed_video_buf_queue,
>> +};
>> +
>> +static int aspeed_video_setup_video(struct aspeed_video *video)
>> +{
>> +	const u64 mask = ~(BIT(V4L2_JPEG_CHROMA_SUBSAMPLING_444) |
>> +			   BIT(V4L2_JPEG_CHROMA_SUBSAMPLING_420));
>> +	struct v4l2_device *v4l2_dev = &video->v4l2_dev;
>> +	struct vb2_queue *vbq = &video->queue;
>> +	struct video_device *vdev = &video->vdev;
>> +	int rc;
>> +
>> +	video->pix_fmt.pixelformat = V4L2_PIX_FMT_JPEG;
>> +	video->pix_fmt.field = V4L2_FIELD_NONE;
>> +	video->pix_fmt.colorspace = V4L2_COLORSPACE_SRGB;
>> +	video->pix_fmt.quantization = V4L2_QUANTIZATION_FULL_RANGE;
>> +
>> +	rc = v4l2_device_register(video->dev, v4l2_dev);
>> +	if (rc) {
>> +		dev_err(video->dev, "Failed to register v4l2 device\n");
>> +		return rc;
>> +	}
>> +
>> +	v4l2_ctrl_handler_init(&video->ctrl_handler, 2);
>> +	v4l2_ctrl_new_std(&video->ctrl_handler, &aspeed_video_ctrl_ops,
>> +			  V4L2_CID_JPEG_COMPRESSION_QUALITY, 0,
>> +			  ASPEED_VIDEO_JPEG_NUM_QUALITIES - 1, 1, 0);
>> +	v4l2_ctrl_new_std_menu(&video->ctrl_handler, &aspeed_video_ctrl_ops,
>> +			       V4L2_CID_JPEG_CHROMA_SUBSAMPLING,
>> +			       V4L2_JPEG_CHROMA_SUBSAMPLING_420, mask,
>> +			       V4L2_JPEG_CHROMA_SUBSAMPLING_444);
>> +
>> +	if (video->ctrl_handler.error) {
>> +		v4l2_ctrl_handler_free(&video->ctrl_handler);
>> +		v4l2_device_unregister(v4l2_dev);
>> +
>> +		dev_err(video->dev, "Failed to init controls: %d\n",
>> +			video->ctrl_handler.error);
>> +		return rc;
>> +	}
>> +
>> +	v4l2_dev->ctrl_handler = &video->ctrl_handler;
>> +
>> +	vbq->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>> +	vbq->io_modes = VB2_MMAP | VB2_READ | VB2_DMABUF;
>> +	vbq->dev = v4l2_dev->dev;
>> +	vbq->lock = &video->video_lock;
>> +	vbq->ops = &aspeed_video_vb2_ops;
>> +	vbq->mem_ops = &vb2_dma_contig_memops;
>> +	vbq->drv_priv = video;
>> +	vbq->buf_struct_size = sizeof(struct aspeed_video_buffer);
>> +	vbq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
>> +	vbq->min_buffers_needed = 3;
>> +
>> +	rc = vb2_queue_init(vbq);
>> +	if (rc) {
>> +		v4l2_ctrl_handler_free(&video->ctrl_handler);
>> +		v4l2_device_unregister(v4l2_dev);
>> +
>> +		dev_err(video->dev, "Failed to init vb2 queue\n");
>> +		return rc;
>> +	}
>> +
>> +	vdev->queue = vbq;
>> +	vdev->fops = &aspeed_video_v4l2_fops;
>> +	vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_READWRITE |
> READWRITE doesn't work for JPEG since there is no clear end of a frame. Just drop
> this and the read op in aspeed_video_v4l2_fops.

I don't follow. The buffer will have the payload set correctly, defining 
the end of the frame, right? I haven't tested the read interface now but 
looking at the vb2_fop_read I think it would work?

Thanks,
Eddie

>
>> +		V4L2_CAP_STREAMING;
>> +	vdev->v4l2_dev = v4l2_dev;
>> +	strscpy(vdev->name, DEVICE_NAME, sizeof(vdev->name));
>> +	vdev->vfl_type = VFL_TYPE_GRABBER;
>> +	vdev->vfl_dir = VFL_DIR_RX;
>> +	vdev->release = video_device_release_empty;
>> +	vdev->ioctl_ops = &aspeed_video_ioctl_ops;
>> +	vdev->lock = &video->video_lock;
>> +
>> +	video_set_drvdata(vdev, video);
>> +	rc = video_register_device(vdev, VFL_TYPE_GRABBER, 0);
>> +	if (rc) {
>> +		vb2_queue_release(vbq);
>> +		v4l2_ctrl_handler_free(&video->ctrl_handler);
>> +		v4l2_device_unregister(v4l2_dev);
>> +
>> +		dev_err(video->dev, "Failed to register video device\n");
>> +		return rc;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_init(struct aspeed_video *video)
>> +{
>> +	int irq;
>> +	int rc;
>> +	struct device *dev = video->dev;
>> +
>> +	irq = irq_of_parse_and_map(dev->of_node, 0);
>> +	if (!irq) {
>> +		dev_err(dev, "Unable to find IRQ\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	rc = devm_request_irq(dev, irq, aspeed_video_irq, IRQF_SHARED,
>> +			      DEVICE_NAME, video);
>> +	if (rc < 0) {
>> +		dev_err(dev, "Unable to request IRQ %d\n", irq);
>> +		return rc;
>> +	}
>> +
>> +	video->eclk = devm_clk_get(dev, "eclk");
>> +	if (IS_ERR(video->eclk)) {
>> +		dev_err(dev, "Unable to get ECLK\n");
>> +		return PTR_ERR(video->eclk);
>> +	}
>> +
>> +	video->vclk = devm_clk_get(dev, "vclk");
>> +	if (IS_ERR(video->vclk)) {
>> +		dev_err(dev, "Unable to get VCLK\n");
>> +		return PTR_ERR(video->vclk);
>> +	}
>> +
>> +	video->rst = devm_reset_control_get_exclusive(dev, NULL);
>> +	if (IS_ERR(video->rst)) {
>> +		dev_err(dev, "Unable to get VE reset\n");
>> +		return PTR_ERR(video->rst);
>> +	}
>> +
>> +	rc = of_reserved_mem_device_init(dev);
>> +	if (rc) {
>> +		dev_err(dev, "Unable to reserve memory\n");
>> +		return rc;
>> +	}
>> +
>> +	rc = dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
>> +	if (rc) {
>> +		dev_err(dev, "Failed to set DMA mask\n");
>> +		of_reserved_mem_device_release(dev);
>> +		return rc;
>> +	}
>> +
>> +	if (!aspeed_video_alloc_buf(video, &video->jpeg,
>> +				    VE_JPEG_HEADER_SIZE)) {
>> +		dev_err(dev, "Failed to allocate DMA for JPEG header\n");
>> +		of_reserved_mem_device_release(dev);
>> +		return rc;
>> +	}
>> +
>> +	aspeed_video_init_jpeg_table(video->jpeg.virt, video->yuv420);
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_probe(struct platform_device *pdev)
>> +{
>> +	int rc;
>> +	struct resource *res;
>> +	struct aspeed_video *video = kzalloc(sizeof(*video), GFP_KERNEL);
>> +
>> +	if (!video)
>> +		return -ENOMEM;
>> +
>> +	video->frame_rate = 30;
>> +	video->dev = &pdev->dev;
>> +	mutex_init(&video->video_lock);
>> +	init_waitqueue_head(&video->wait);
>> +	INIT_DELAYED_WORK(&video->res_work, aspeed_video_resolution_work);
>> +	INIT_LIST_HEAD(&video->buffers);
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +
>> +	video->base = devm_ioremap_resource(video->dev, res);
>> +
>> +	if (IS_ERR(video->base))
>> +		return PTR_ERR(video->base);
>> +
>> +	rc = aspeed_video_init(video);
>> +	if (rc)
>> +		return rc;
>> +
>> +	rc = aspeed_video_setup_video(video);
>> +	if (rc)
>> +		return rc;
>> +
>> +	return 0;
>> +}
>> +
>> +static int aspeed_video_remove(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct v4l2_device *v4l2_dev = dev_get_drvdata(dev);
>> +	struct aspeed_video *video = to_aspeed_video(v4l2_dev);
>> +
>> +	video_unregister_device(&video->vdev);
>> +
>> +	vb2_queue_release(&video->queue);
>> +
>> +	v4l2_ctrl_handler_free(&video->ctrl_handler);
>> +
>> +	v4l2_device_unregister(v4l2_dev);
>> +
>> +	dma_free_coherent(video->dev, VE_JPEG_HEADER_SIZE, video->jpeg.virt,
>> +			  video->jpeg.dma);
>> +
>> +	of_reserved_mem_device_release(dev);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id aspeed_video_of_match[] = {
>> +	{ .compatible = "aspeed,ast2400-video-engine" },
>> +	{ .compatible = "aspeed,ast2500-video-engine" },
>> +	{}
>> +};
>> +MODULE_DEVICE_TABLE(of, aspeed_video_of_match);
>> +
>> +static struct platform_driver aspeed_video_driver = {
>> +	.driver = {
>> +		.name = DEVICE_NAME,
>> +		.of_match_table = aspeed_video_of_match,
>> +	},
>> +	.probe = aspeed_video_probe,
>> +	.remove = aspeed_video_remove,
>> +};
>> +
>> +module_platform_driver(aspeed_video_driver);
>> +
>> +MODULE_DESCRIPTION("ASPEED Video Engine Driver");
>> +MODULE_AUTHOR("Eddie James");
>> +MODULE_LICENSE("GPL v2");
>>
> Regards,
>
> 	Hans
>