[libcamera-devel] [PATCH 05/11] libcamera: ipu3: cio2: Return the FrameBuffer pointer used

[Jacopo Mondi]

Hi Niklas,

On Thu, Nov 05, 2020 at 01:15:40AM +0100, Niklas Söderlund wrote:
> When adding IPA plumbing to the IPU3 pipeline handler it will be needed
> to track witch raw buffer was queued to the CIO2 for a specific request.

s/witch/which

> Currently if using an internally allocated raw buffer the FrameBuffer is
> not exposed outside the CIO2Device as it was not needed. Prepare for the
> IPA by exposing which infernal raw buffer is picked for each request,

s/infernal/internal

With 'witch raw buffers' and 'infernal raw buffers' I'm sure libcamera
would gain much more esoteric super-powers. I like it!

> later changes will associate this with a Request.
>
> Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> ---
>  src/libcamera/pipeline/ipu3/cio2.cpp | 10 +++++++---
>  src/libcamera/pipeline/ipu3/cio2.h   |  2 +-
>  src/libcamera/pipeline/ipu3/ipu3.cpp |  8 ++++----
>  3 files changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/src/libcamera/pipeline/ipu3/cio2.cpp b/src/libcamera/pipeline/ipu3/cio2.cpp
> index e43ec70fe3e4e0db..1c7b9676f52abdb6 100644
> --- a/src/libcamera/pipeline/ipu3/cio2.cpp
> +++ b/src/libcamera/pipeline/ipu3/cio2.cpp
> @@ -262,7 +262,7 @@ int CIO2Device::stop()
>  	return ret;
>  }
>
> -int CIO2Device::queueBuffer(Request *request, FrameBuffer *rawBuffer)
> +FrameBuffer *CIO2Device::queueBuffer(Request *request, FrameBuffer *rawBuffer)
>  {
>  	FrameBuffer *buffer = rawBuffer;
>
> @@ -270,7 +270,7 @@ int CIO2Device::queueBuffer(Request *request, FrameBuffer *rawBuffer)
>  	if (!buffer) {
>  		if (availableBuffers_.empty()) {
>  			LOG(IPU3, Error) << "CIO2 buffer underrun";
> -			return -EINVAL;
> +			return nullptr;
>  		}
>
>  		buffer = availableBuffers_.front();
> @@ -279,7 +279,11 @@ int CIO2Device::queueBuffer(Request *request, FrameBuffer *rawBuffer)
>
>  	buffer->setRequest(request);
>
> -	return output_->queueBuffer(buffer);
> +	int ret = output_->queueBuffer(buffer);
> +	if (ret)
> +		return nullptr;
> +
> +	return buffer;
>  }
>
>  void CIO2Device::tryReturnBuffer(FrameBuffer *buffer)
> diff --git a/src/libcamera/pipeline/ipu3/cio2.h b/src/libcamera/pipeline/ipu3/cio2.h
> index fa813a989fd21aec..e8b491a0c104a3e2 100644
> --- a/src/libcamera/pipeline/ipu3/cio2.h
> +++ b/src/libcamera/pipeline/ipu3/cio2.h
> @@ -52,7 +52,7 @@ public:
>  	CameraSensor *sensor() { return sensor_; }
>  	const CameraSensor *sensor() const { return sensor_; }
>
> -	int queueBuffer(Request *request, FrameBuffer *rawBuffer);
> +	FrameBuffer *queueBuffer(Request *request, FrameBuffer *rawBuffer);
>  	void tryReturnBuffer(FrameBuffer *buffer);
>  	Signal<FrameBuffer *> &bufferReady() { return output_->bufferReady; }
>
> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> index c559d160084f87e7..62e99a308a6136a7 100644
> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> @@ -643,10 +643,10 @@ int PipelineHandlerIPU3::queueRequestDevice(Camera *camera, Request *request)
>  	 * Queue a buffer on the CIO2, using the raw stream buffer provided in
>  	 * the request, if any, or a CIO2 internal buffer otherwise.
>  	 */
> -	FrameBuffer *rawBuffer = request->findBuffer(&data->rawStream_);
> -	error = data->cio2_.queueBuffer(request, rawBuffer);
> -	if (error)
> -		return error;
> +	FrameBuffer *reqRawBuffer = request->findBuffer(&data->rawStream_);
> +	FrameBuffer *rawBuffer = data->cio2_.queueBuffer(request, reqRawBuffer);

I wonder if we should not better overload CIO2Device::queueBuffer(),
one version that accepts an externally provided buffer, and one that
uses an internal one. We can't overload on return value, so they
should be named differently, but the code here would look like:

        FrameBuffer *rawBuffer = request->findBuffer(&data->rawStream_);
        int ret;
        if (!rawBuffer) {
                rawBuffer = data->cio2_.queueInternalBuffer(request);
                ret = !!rawBuffer;
        } else {
                ret = data->cio2_.queueInternalBuffer(request, rawBuffer);
        }
        if (ret)
                return -ENOMEM;

It's less compact but more explicit. Up to you, what you have here is
good as well

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

Thanks
   j

> +	if (!rawBuffer)
> +		return -ENOMEM;
>
>  	/* Queue all buffers from the request aimed for the ImgU. */
>  	for (auto it : request->buffers()) {
> --
> 2.29.2
>
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