[libcamera-devel] [PATCH v3 30/30] v4l2: Sum bytesused for all planes when dequeuing buffer

[Kieran Bingham]

On 06/09/2021 23:56, Laurent Pinchart wrote:
> The V4L2 compatibility layer supports the single-planar API only, and
> thuss expose a single V4L2 buffer plane to applications, regardless of

s/thuss/thus/
s/expose/exposes/

> the number of planes in the FrameBuffer. For multi-planar frame buffers,
> the bytesused value isn't correct as it only takes the first plane into
> account. Fix it by summing the bytesused values for all FrameBuffer
> planes.
> 
> Signed-off-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
>  src/v4l2/v4l2_camera_proxy.cpp | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
> index 07d2250bb846..aeffef26c5bf 100644
> --- a/src/v4l2/v4l2_camera_proxy.cpp
> +++ b/src/v4l2/v4l2_camera_proxy.cpp
> @@ -11,6 +11,7 @@
>  #include <array>
>  #include <errno.h>
>  #include <linux/videodev2.h>
> +#include <numeric>
>  #include <set>
>  #include <string.h>
>  #include <sys/mman.h>
> @@ -211,7 +212,11 @@ void V4L2CameraProxy::updateBuffers()
>  
>  		switch (fmd.status) {
>  		case FrameMetadata::FrameSuccess:
> -			buf.bytesused = fmd.planes()[0].bytesused;
> +			buf.bytesused = std::accumulate(fmd.planes().begin(),
> +							fmd.planes().end(), 0,
> +							[](unsigned int total, const auto &plane) {

lambda's always look like black magic to me.
I assume total is either automatically initialised, or initialised by
the 0 after fmd.planes().end()

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> +								return total + plane.bytesused;
> +							});
>  			buf.field = V4L2_FIELD_NONE;
>  			buf.timestamp.tv_sec = fmd.timestamp / 1000000000;
>  			buf.timestamp.tv_usec = fmd.timestamp % 1000000;
>