[libcamera-devel] [PATCH 12/15] v4l2: v4l2_camera_proxy: Add sequence number

[Jacopo Mondi]

Hi Paul,

On Tue, Jun 16, 2020 at 10:12:41PM +0900, Paul Elder wrote:
> Populate the sequence number field in the V4L2 buffers. Reset upon
> streamon.
>
> Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
> ---
>  src/v4l2/v4l2_camera_proxy.cpp | 4 +++-
>  src/v4l2/v4l2_camera_proxy.h   | 2 ++
>  2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> index 079961a..81f9282 100644
> --- a/src/v4l2/v4l2_camera_proxy.cpp
> +++ b/src/v4l2/v4l2_camera_proxy.cpp
> @@ -33,7 +33,7 @@ LOG_DECLARE_CATEGORY(V4L2Compat);
>  V4L2CameraProxy::V4L2CameraProxy(unsigned int index,
>  				 std::shared_ptr<Camera> camera)
>  	: refcount_(0), index_(index), bufferCount_(0), currentBuf_(0),
> -	  vcam_(std::make_unique<V4L2Camera>(camera)), efd_(-1),
> +	  sequence_(0), vcam_(std::make_unique<V4L2Camera>(camera)), efd_(-1),

Why not use the sequence number reported by the video device and
available in the frame metadata ?

>  	  v4l2RecordPriorityFd_(-1), acquiredFd_(-1), initialized_(false),
>  	  streaming_(false)
>  {
> @@ -665,6 +665,7 @@ int V4L2CameraProxy::vidioc_dqbuf(int fd, struct v4l2_buffer *arg)
>
>  	buf.flags &= ~V4L2_BUF_FLAG_QUEUED;
>  	buf.length = sizeimage_;
> +	buf.sequence = sequence_++;
>  	*arg = buf;
>
>  	currentBuf_ = (currentBuf_ + 1) % bufferCount_;
> @@ -696,6 +697,7 @@ int V4L2CameraProxy::vidioc_streamon(int fd, int *arg)
>
>  	currentBuf_ = 0;
>  	streaming_ = true;
> +	sequence_ = 0;
>
>  	return vcam_->streamOn();
>  }
> diff --git a/src/v4l2/v4l2_camera_proxy.h b/src/v4l2/v4l2_camera_proxy.h
> index 28b2fa0..1d8e9a6 100644
> --- a/src/v4l2/v4l2_camera_proxy.h
> +++ b/src/v4l2/v4l2_camera_proxy.h
> @@ -82,6 +82,8 @@ private:
>  	unsigned int currentBuf_;
>  	unsigned int sizeimage_;
>
> +	uint32_t sequence_;
> +
>  	std::vector<struct v4l2_buffer> buffers_;
>  	std::map<void *, unsigned int> mmaps_;
>
> --
> 2.27.0
>
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