[libcamera-devel] [PATCH] pipeline: rpi: vc4: Allocate more embedded data buffers

[Naushir Patuck]

Hi William,

Thank you for this patch.

On Mon, 18 Sept 2023 at 10:31, William Vinnicombe via libcamera-devel
<libcamera-devel at lists.libcamera.org> wrote:
>
> If the pipeline runs out of embedded data buffers, then it will pass
> the frame to the IPA without the metadata. The IPA then has to use the
> delayed controls as inputs to the algorithms. This can cause problems
> with the subsequent algorithms if the sensor did not action the
> controls, especially with the autofocus as that doesn't have controls
> which can be passed in lieu of the metadata.
>
> Reduce the likelihood of this by increasing the number of embedded data
> buffers, as they are small so a generous number can be allocated.
>
> Signed-off-by: William Vinnicombe <william.vinnicombe at raspberrypi.com>

Makes sense!

Reviewed-by: Naushir Patuck <naush at raspberrypi.com>

> ---
>  src/libcamera/pipeline/rpi/vc4/vc4.cpp | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/src/libcamera/pipeline/rpi/vc4/vc4.cpp b/src/libcamera/pipeline/rpi/vc4/vc4.cpp
> index 018cf488..6777c697 100644
> --- a/src/libcamera/pipeline/rpi/vc4/vc4.cpp
> +++ b/src/libcamera/pipeline/rpi/vc4/vc4.cpp
> @@ -262,9 +262,9 @@ int PipelineHandlerVc4::prepareBuffers(Camera *camera)
>                 } else if (stream == &data->unicam_[Unicam::Embedded]) {
>                         /*
>                          * Embedded data buffers are (currently) for internal use,
> -                        * so allocate the minimum required to avoid frame drops.
> +                        * so allocate a generous number as they are small.
>                          */
> -                       numBuffers = minBuffers;
> +                       numBuffers = 12;
>                 } else {
>                         /*
>                          * Since the ISP runs synchronous with the IPA and requests,
> --
> 2.39.2
>