[libcamera-devel] [PATCH] pipeline: ipu3: Store requests in the case a buffer shortage

[Hirokazu Honda]

I should still work for this patch series.
The missing part is to trigger queuePendingRequests() appropriately
when buffers are available.
I couldn't find a good way as availableBuffers notification functions
are separated and trying queuePendingRequests() is not likely
successful and thus inefficient.
I would like to ask anyone for a good idea for this.

Thanks in advance,
-Hiro

On Wed, Mar 31, 2021 at 5:45 PM Hirokazu Honda <hiroh at chromium.org> wrote:
>
> PipelineHandlerIPU3 returns -ENOBUFS and -ENOMEM on queueing a
> request when there are not sufficient buffers for the request.
> Since the request will be successful if it is queued later when
> enough buffers are available. The requests failed due to a buffer
> shortage should be stored and retried later in the FIFO order.
> This introduces the queue in PipelineHandlerIPU3 to do that.
>
> Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> ---
>  src/libcamera/pipeline/ipu3/ipu3.cpp | 62 ++++++++++++++++++----------
>  1 file changed, 41 insertions(+), 21 deletions(-)
>
> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> index 519cad4f..71dd311f 100644
> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> @@ -153,12 +153,16 @@ private:
>         int allocateBuffers(Camera *camera);
>         int freeBuffers(Camera *camera);
>
> +       int queuePendingRequests();
> +
>         ImgUDevice imgu0_;
>         ImgUDevice imgu1_;
>         MediaDevice *cio2MediaDev_;
>         MediaDevice *imguMediaDev_;
>
>         std::vector<IPABuffer> ipaBuffers_;
> +
> +       std::queue<std::pair<IPU3CameraData *, Request *>> pendingRequests_;
>  };
>
>  IPU3CameraConfiguration::IPU3CameraConfiguration(IPU3CameraData *data)
> @@ -764,6 +768,8 @@ void PipelineHandlerIPU3::stop(Camera *camera)
>         IPU3CameraData *data = cameraData(camera);
>         int ret = 0;
>
> +       pendingRequests_ = {};
> +
>         data->ipa_->stop();
>
>         ret |= data->imgu_->stop();
> @@ -774,36 +780,50 @@ void PipelineHandlerIPU3::stop(Camera *camera)
>         freeBuffers(camera);
>  }
>
> -int PipelineHandlerIPU3::queueRequestDevice(Camera *camera, Request *request)
> +int PipelineHandlerIPU3::queuePendingRequests()
>  {
> -       IPU3CameraData *data = cameraData(camera);
> +       while (!pendingRequests_.empty()) {
> +               IPU3CameraData *data = pendingRequests_.front().first;
> +               Request *request = pendingRequests_.front().second;
>
> -       IPU3Frames::Info *info = data->frameInfos_.create(request);
> -       if (!info)
> -               return -ENOBUFS;
> +               IPU3Frames::Info *info = data->frameInfos_.create(request);
> +               if (!info)
> +                       break;
>
> -       /*
> -        * Queue a buffer on the CIO2, using the raw stream buffer provided in
> -        * the request, if any, or a CIO2 internal buffer otherwise.
> -        */
> -       FrameBuffer *reqRawBuffer = request->findBuffer(&data->rawStream_);
> -       FrameBuffer *rawBuffer = data->cio2_.queueBuffer(request, reqRawBuffer);
> -       if (!rawBuffer) {
> -               data->frameInfos_.remove(info);
> -               return -ENOMEM;
> -       }
> +               /*
> +                * Queue a buffer on the CIO2, using the raw stream buffer
> +                * provided in the request, if any, or a CIO2 internal buffer
> +                * otherwise.
> +                */
> +               FrameBuffer *reqRawBuffer = request->findBuffer(&data->rawStream_);
> +               FrameBuffer *rawBuffer = data->cio2_.queueBuffer(request, reqRawBuffer);
> +               if (!rawBuffer) {
> +                       data->frameInfos_.remove(info);
> +                       break;
> +               }
>
> -       info->rawBuffer = rawBuffer;
> +               info->rawBuffer = rawBuffer;
>
> -       ipa::ipu3::IPU3Event ev;
> -       ev.op = ipa::ipu3::EventProcessControls;
> -       ev.frame = info->id;
> -       ev.controls = request->controls();
> -       data->ipa_->processEvent(ev);
> +               ipa::ipu3::IPU3Event ev;
> +               ev.op = ipa::ipu3::EventProcessControls;
> +               ev.frame = info->id;
> +               ev.controls = request->controls();
> +               data->ipa_->processEvent(ev);
> +
> +               pendingRequests_.pop();
> +       }
>
>         return 0;
>  }
>
> +int PipelineHandlerIPU3::queueRequestDevice(Camera *camera, Request *request)
> +{
> +       IPU3CameraData *data = cameraData(camera);
> +
> +       pendingRequests_.emplace(data, request);
> +       return queuePendingRequests();
> +}
> +
>  bool PipelineHandlerIPU3::match(DeviceEnumerator *enumerator)
>  {
>         int ret;
> --
> 2.31.0.291.g576ba9dcdaf-goog
>