[libcamera-devel] [PATCH v2 7/9] android: camera_device: Move buffer mapping for post processing

[Laurent Pinchart]

Hi Umang,

Thank you for the patch.

On Fri, Sep 10, 2021 at 12:36:36PM +0530, Umang Jain wrote:
> Buffer mapping for post processing currently happens in
> CameraStream::process(). However, it can be easily be moved to
> CameraDevice just before the call to CameraStream::process(). The
> reason to do so is that, we can hold the mapped destination buffer
> pointer as a part of Camera3RequestDescriptor. Camera3RequestDescriptor
> already hold other post-processing related context to enable async post
> processing in subsequent commits.

Why is it better to map the buffer in CameraDevice::requestComplete() ?
As mapping can be a costly operation, it seems better to me to move it
to the post-processor thread instead.

> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
>  src/android/camera_device.cpp | 14 +++++++++++++-
>  src/android/camera_device.h   |  1 +
>  src/android/camera_stream.cpp | 16 ++--------------
>  src/android/camera_stream.h   |  2 +-
>  4 files changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
> index 7f04d225..988d4232 100644
> --- a/src/android/camera_device.cpp
> +++ b/src/android/camera_device.cpp
> @@ -1163,13 +1163,25 @@ void CameraDevice::requestComplete(Request *request)
>  		descriptor.resultMetadata_ = std::move(resultMetadata);
>  		descriptor.captureResult_ = captureResult;
>  
> +		/* \todo Buffer mapping should be moved to a separate thread? */
> +		const StreamConfiguration &output = cameraStream->configuration();
> +		descriptor.destBuffer_ = std::make_unique<CameraBuffer>(
> +			*buffer.buffer, formats::MJPEG, output.size,
> +			PROT_READ | PROT_WRITE);
> +
> +		if (!descriptor.destBuffer_->isValid()) {
> +			LOG(HAL, Error) << "Failed to map android blob buffer";
> +			return;
> +		}
> +
>  		std::unique_ptr<Camera3RequestDescriptor> reqDescriptor =
>  			std::make_unique<Camera3RequestDescriptor>();
>  		*reqDescriptor = std::move(descriptor);
>  		queuedDescriptor_.push_back(std::move(reqDescriptor));
>  
>  		Camera3RequestDescriptor *currentDescriptor = queuedDescriptor_.back().get();
> -		int ret = cameraStream->process(src, *buffer.buffer,
> +		int ret = cameraStream->process(src,
> +						currentDescriptor->destBuffer_.get(),
>  						currentDescriptor->settings_,
>  						currentDescriptor->resultMetadata_.get(),
>  						currentDescriptor);
> diff --git a/src/android/camera_device.h b/src/android/camera_device.h
> index e7318358..b62d373c 100644
> --- a/src/android/camera_device.h
> +++ b/src/android/camera_device.h
> @@ -58,6 +58,7 @@ struct Camera3RequestDescriptor {
>  		Failed,
>  	};
>  	std::unique_ptr<CameraMetadata> resultMetadata_;
> +	std::unique_ptr<CameraBuffer> destBuffer_;
>  	camera3_capture_result_t captureResult_;
>  	libcamera::FrameBuffer *internalBuffer_;
>  	completionStatus status_;
> diff --git a/src/android/camera_stream.cpp b/src/android/camera_stream.cpp
> index c7d874b2..5fd04bbf 100644
> --- a/src/android/camera_stream.cpp
> +++ b/src/android/camera_stream.cpp
> @@ -102,7 +102,7 @@ int CameraStream::configure()
>  }
>  
>  int CameraStream::process(const FrameBuffer *source,
> -			  buffer_handle_t camera3Dest,
> +			  CameraBuffer *destBuffer,
>  			  const CameraMetadata &requestMetadata,
>  			  CameraMetadata *resultMetadata,
>  			  const Camera3RequestDescriptor *context)
> @@ -110,19 +110,7 @@ int CameraStream::process(const FrameBuffer *source,
>  	if (!postProcessor_)
>  		return 0;
>  
> -	/*
> -	 * \todo Buffer mapping and processing should be moved to a
> -	 * separate thread.
> -	 */
> -	const StreamConfiguration &output = configuration();
> -	CameraBuffer dest(camera3Dest, formats::MJPEG, output.size,
> -			  PROT_READ | PROT_WRITE);
> -	if (!dest.isValid()) {
> -		LOG(HAL, Error) << "Failed to map android blob buffer";
> -		return -EINVAL;
> -	}
> -
> -	return postProcessor_->process(source, &dest, requestMetadata,
> +	return postProcessor_->process(source, destBuffer, requestMetadata,
>  				       resultMetadata, context);
>  }
>  
> diff --git a/src/android/camera_stream.h b/src/android/camera_stream.h
> index be076995..8097ddbc 100644
> --- a/src/android/camera_stream.h
> +++ b/src/android/camera_stream.h
> @@ -124,7 +124,7 @@ public:
>  
>  	int configure();
>  	int process(const libcamera::FrameBuffer *source,
> -		    buffer_handle_t camera3Dest,
> +		    CameraBuffer *destBuffer,
>  		    const CameraMetadata &requestMetadata,
>  		    CameraMetadata *resultMetadata,
>  		    const Camera3RequestDescriptor *context);

-- 
Regards,

Laurent Pinchart