[libcamera-devel] [PATCH 05/10] libcamera: ipu3: Calculate number of buffers for ImgU

[Jacopo Mondi]

Hi Niklas,

On Tue, Jun 02, 2020 at 03:39:04AM +0200, Niklas Söderlund wrote:
> Decouple the number of buffers to allocate for the ImgU from the number
> of buffers allocated for the CIO2. Instead of blindly following the CIO2
> pick the maximum number of buffers requested for any stream facing
> applications.
>
> This is potentially wasteful, as each stream could allocate just as many
> buffers as requested by the application instead of the maximum from the
> set. But this is not more wasteful then whats already used by the
> pipeline and should be fixed on top after the decoupling of the two
> processing units.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  src/libcamera/pipeline/ipu3/ipu3.cpp | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> index 0e7555c716b36749..f4759715c6ae7572 100644
> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> @@ -729,14 +729,16 @@ int PipelineHandlerIPU3::allocateBuffers(Camera *camera)
>  	IPU3CameraData *data = cameraData(camera);
>  	CIO2Device *cio2 = &data->cio2_;
>  	ImgUDevice *imgu = data->imgu_;
> -	unsigned int bufferCount;
> +	unsigned int bufferCount = 0;
>  	int ret;
>
>  	ret = cio2->allocateBuffers();
>  	if (ret < 0)
>  		return ret;
>
> -	bufferCount = ret;
> +	bufferCount = std::max<unsigned int>(data->outStream_.configuration().bufferCount, bufferCount);
> +	bufferCount = std::max<unsigned int>(data->vfStream_.configuration().bufferCount, bufferCount);
> +	bufferCount = std::max<unsigned int>(data->rawStream_.configuration().bufferCount, bufferCount);

I don't have a strong opinion on the underlying idea, I think it's
better than assuming we should report the number of buffer needed by
the CIO2 unit.

On the patch itself, could you shorten it by
        buffercount = max(outstream, vfStream);
        buffercounf = max(buffercount, rawStream)

That apart
Reviewed-by: Jacopo Mondi <jacopo at jmondi.org>

Thanks
   j
>
>  	ret = imgu->allocateBuffers(data, bufferCount);
>  	if (ret < 0) {
> --
> 2.26.2
>
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