[libcamera-devel,v4,03/12] libcamera: camera: allocateBuffers: Pass the stream set

Message ID 20190409192548.20325-4-jacopo@jmondi.org
State Superseded
Headers show
Series
  • libcamera: ipu3: Multiple streams support
Related show

Commit Message

Jacopo Mondi April 9, 2019, 7:25 p.m. UTC
Pipeline handlers might need to perform allocation of internal buffers,
setup operations, or simple sanity check before going into the
per-stream buffer allocation.

As of now, PipelineHandler::allocateBuffers() is called once for each
active stream, leaving no space for stream-independent configuration.

Change this by providing to the pipeline handlers the full set of active
streams, and ask them to loop over them to perform per-streams
allocations.

While at it, propagate the freeBuffer() error code to the applications
in case of failure.

Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
---
 src/libcamera/camera.cpp                 | 17 +++++++++--------
 src/libcamera/include/pipeline_handler.h |  6 ++++--
 src/libcamera/pipeline/ipu3/ipu3.cpp     | 13 +++++++++----
 src/libcamera/pipeline/uvcvideo.cpp      | 13 +++++++++----
 src/libcamera/pipeline/vimc.cpp          | 13 +++++++++----
 src/libcamera/pipeline_handler.cpp       | 11 ++++++-----
 6 files changed, 46 insertions(+), 27 deletions(-)

Comments

Niklas Söderlund April 14, 2019, 7:53 p.m. UTC | #1
Hi Jacopo,

Thanks for your patch.

On 2019-04-09 21:25:39 +0200, Jacopo Mondi wrote:
> Pipeline handlers might need to perform allocation of internal buffers,
> setup operations, or simple sanity check before going into the
> per-stream buffer allocation.
> 
> As of now, PipelineHandler::allocateBuffers() is called once for each
> active stream, leaving no space for stream-independent configuration.
> 
> Change this by providing to the pipeline handlers the full set of active
> streams, and ask them to loop over them to perform per-streams
> allocations.
> 
> While at it, propagate the freeBuffer() error code to the applications
> in case of failure.

I think you should do this in a separate patch... yea I know you heard 
it before. I'm going to keep pestering you with comments about this as 
reviewing patches larger then ~40 lines which do more then one thing is 
a huge pain for me ;-)

> 
> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

I think you can put this patch at the beginning of the series or 
potentially merge/post it as a separate patch as it solves a design 
issue not strictly related to the IPU3 code.

I would drop 'allocateBuffers:' from the path subject as it's not our 
convention to annotate using function names, how about

    libcamera: camera: Pass all active streams in allocateBuffers()

With the subject fixed and with or without breaking the patch in two,

Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>

> ---
>  src/libcamera/camera.cpp                 | 17 +++++++++--------
>  src/libcamera/include/pipeline_handler.h |  6 ++++--
>  src/libcamera/pipeline/ipu3/ipu3.cpp     | 13 +++++++++----
>  src/libcamera/pipeline/uvcvideo.cpp      | 13 +++++++++----
>  src/libcamera/pipeline/vimc.cpp          | 13 +++++++++----
>  src/libcamera/pipeline_handler.cpp       | 11 ++++++-----
>  6 files changed, 46 insertions(+), 27 deletions(-)
> 
> diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> index bdf14b31d8ee..cb392ca3b7e7 100644
> --- a/src/libcamera/camera.cpp
> +++ b/src/libcamera/camera.cpp
> @@ -647,13 +647,11 @@ int Camera::allocateBuffers()
>  		return -EINVAL;
>  	}
>  
> -	for (Stream *stream : activeStreams_) {
> -		int ret = pipe_->allocateBuffers(this, stream);
> -		if (ret) {
> -			LOG(Camera, Error) << "Failed to allocate buffers";
> -			freeBuffers();
> -			return ret;
> -		}
> +	int ret = pipe_->allocateBuffers(this, activeStreams_);
> +	if (ret) {
> +		LOG(Camera, Error) << "Failed to allocate buffers";
> +		freeBuffers();
> +		return ret;
>  	}
>  
>  	state_ = CameraPrepared;
> @@ -683,9 +681,12 @@ int Camera::freeBuffers()
>  		 * by the V4L2 device that has allocated them.
>  		 */
>  		stream->bufferPool().destroyBuffers();
> -		pipe_->freeBuffers(this, stream);
>  	}
>  
> +	int ret = pipe_->freeBuffers(this, activeStreams_);
> +	if (ret)
> +		return ret;
> +
>  	state_ = CameraConfigured;
>  
>  	return 0;
> diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
> index b6cbd3bae51b..253820e8eaf8 100644
> --- a/src/libcamera/include/pipeline_handler.h
> +++ b/src/libcamera/include/pipeline_handler.h
> @@ -57,8 +57,10 @@ public:
>  	streamConfiguration(Camera *camera, const std::vector<StreamUsage> &usages) = 0;
>  	virtual int configureStreams(Camera *camera, const CameraConfiguration &config) = 0;
>  
> -	virtual int allocateBuffers(Camera *camera, Stream *stream) = 0;
> -	virtual int freeBuffers(Camera *camera, Stream *stream) = 0;
> +	virtual int allocateBuffers(Camera *camera,
> +				    const std::set<Stream *> &streams) = 0;
> +	virtual int freeBuffers(Camera *camera,
> +				const std::set<Stream *> &streams) = 0;
>  
>  	virtual int start(Camera *camera) = 0;
>  	virtual void stop(Camera *camera);
> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> index 712e57c5a459..527213a8970a 100644
> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> @@ -159,8 +159,10 @@ public:
>  	int configureStreams(Camera *camera,
>  			     const CameraConfiguration &config) override;
>  
> -	int allocateBuffers(Camera *camera, Stream *stream) override;
> -	int freeBuffers(Camera *camera, Stream *stream) override;
> +	int allocateBuffers(Camera *camera,
> +			    const std::set<Stream *> &streams) override;
> +	int freeBuffers(Camera *camera,
> +			const std::set<Stream *> &streams) override;
>  
>  	int start(Camera *camera) override;
>  	void stop(Camera *camera) override;
> @@ -378,9 +380,11 @@ int PipelineHandlerIPU3::configureStreams(Camera *camera,
>  	return 0;
>  }
>  
> -int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
> +int PipelineHandlerIPU3::allocateBuffers(Camera *camera,
> +					 const std::set<Stream *> &streams)
>  {
>  	IPU3CameraData *data = cameraData(camera);
> +	Stream *stream = *streams.begin();
>  	CIO2Device *cio2 = &data->cio2_;
>  	ImgUDevice *imgu = data->imgu_;
>  	int ret;
> @@ -419,7 +423,8 @@ int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
>  	return 0;
>  }
>  
> -int PipelineHandlerIPU3::freeBuffers(Camera *camera, Stream *stream)
> +int PipelineHandlerIPU3::freeBuffers(Camera *camera,
> +				     const std::set<Stream *> &streams)
>  {
>  	IPU3CameraData *data = cameraData(camera);
>  
> diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> index cd472cfadd86..b8f634d88b46 100644
> --- a/src/libcamera/pipeline/uvcvideo.cpp
> +++ b/src/libcamera/pipeline/uvcvideo.cpp
> @@ -32,8 +32,10 @@ public:
>  	int configureStreams(Camera *camera,
>  			     const CameraConfiguration &config) override;
>  
> -	int allocateBuffers(Camera *camera, Stream *stream) override;
> -	int freeBuffers(Camera *camera, Stream *stream) override;
> +	int allocateBuffers(Camera *camera,
> +			    const std::set<Stream *> &streams) override;
> +	int freeBuffers(Camera *camera,
> +			const std::set<Stream *> &streams) override;
>  
>  	int start(Camera *camera) override;
>  	void stop(Camera *camera) override;
> @@ -127,9 +129,11 @@ int PipelineHandlerUVC::configureStreams(Camera *camera,
>  	return 0;
>  }
>  
> -int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
> +int PipelineHandlerUVC::allocateBuffers(Camera *camera,
> +					const std::set<Stream *> &streams)
>  {
>  	UVCCameraData *data = cameraData(camera);
> +	Stream *stream = *streams.begin();
>  	const StreamConfiguration &cfg = stream->configuration();
>  
>  	LOG(UVC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
> @@ -137,7 +141,8 @@ int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
>  	return data->video_->exportBuffers(&stream->bufferPool());
>  }
>  
> -int PipelineHandlerUVC::freeBuffers(Camera *camera, Stream *stream)
> +int PipelineHandlerUVC::freeBuffers(Camera *camera,
> +				    const std::set<Stream *> &streams)
>  {
>  	UVCCameraData *data = cameraData(camera);
>  	return data->video_->releaseBuffers();
> diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> index c8bbe2a19847..22449e47bc2d 100644
> --- a/src/libcamera/pipeline/vimc.cpp
> +++ b/src/libcamera/pipeline/vimc.cpp
> @@ -32,8 +32,10 @@ public:
>  	int configureStreams(Camera *camera,
>  			     const CameraConfiguration &config) override;
>  
> -	int allocateBuffers(Camera *camera, Stream *stream) override;
> -	int freeBuffers(Camera *camera, Stream *stream) override;
> +	int allocateBuffers(Camera *camera,
> +			    const std::set<Stream *> &streams) override;
> +	int freeBuffers(Camera *camera,
> +			const std::set<Stream *> &streams) override;
>  
>  	int start(Camera *camera) override;
>  	void stop(Camera *camera) override;
> @@ -127,9 +129,11 @@ int PipelineHandlerVimc::configureStreams(Camera *camera,
>  	return 0;
>  }
>  
> -int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
> +int PipelineHandlerVimc::allocateBuffers(Camera *camera,
> +					 const std::set<Stream *> &streams)
>  {
>  	VimcCameraData *data = cameraData(camera);
> +	Stream *stream = *streams.begin();
>  	const StreamConfiguration &cfg = stream->configuration();
>  
>  	LOG(VIMC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
> @@ -137,7 +141,8 @@ int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
>  	return data->video_->exportBuffers(&stream->bufferPool());
>  }
>  
> -int PipelineHandlerVimc::freeBuffers(Camera *camera, Stream *stream)
> +int PipelineHandlerVimc::freeBuffers(Camera *camera,
> +				     const std::set<Stream *> &streams)
>  {
>  	VimcCameraData *data = cameraData(camera);
>  	return data->video_->releaseBuffers();
> diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> index 43550c0e0210..911d08448e69 100644
> --- a/src/libcamera/pipeline_handler.cpp
> +++ b/src/libcamera/pipeline_handler.cpp
> @@ -193,10 +193,11 @@ PipelineHandler::~PipelineHandler()
>   * \fn PipelineHandler::allocateBuffers()
>   * \brief Allocate buffers for a stream
>   * \param[in] camera The camera the \a stream belongs to
> - * \param[in] stream The stream to allocate buffers for
> + * \param[in] streams The set of streams to allocate buffers for
>   *
> - * This method allocates buffers internally in the pipeline handler and
> - * associates them with the stream's buffer pool.
> + * This method allocates buffers internally in the pipeline handler for each
> + * stream in the \a streams buffer set, and associates them with the stream's
> + * buffer pool.
>   *
>   * The intended caller of this method is the Camera class.
>   *
> @@ -207,9 +208,9 @@ PipelineHandler::~PipelineHandler()
>   * \fn PipelineHandler::freeBuffers()
>   * \brief Free all buffers associated with a stream
>   * \param[in] camera The camera the \a stream belongs to
> - * \param[in] stream The stream to free buffers from
> + * \param[in] streams The set of streams to free buffers from
>   *
> - * After a capture session has been stopped all buffers associated with the
> + * After a capture session has been stopped all buffers associated with each
>   * stream shall be freed.
>   *
>   * The intended caller of this method is the Camera class.
> -- 
> 2.21.0
> 
> _______________________________________________
> libcamera-devel mailing list
> libcamera-devel@lists.libcamera.org
> https://lists.libcamera.org/listinfo/libcamera-devel
Laurent Pinchart April 15, 2019, 11:48 a.m. UTC | #2
Hello,

On Sun, Apr 14, 2019 at 09:53:58PM +0200, Niklas Söderlund wrote:
> On 2019-04-09 21:25:39 +0200, Jacopo Mondi wrote:
> > Pipeline handlers might need to perform allocation of internal buffers,
> > setup operations, or simple sanity check before going into the
> > per-stream buffer allocation.
> > 
> > As of now, PipelineHandler::allocateBuffers() is called once for each
> > active stream, leaving no space for stream-independent configuration.
> > 
> > Change this by providing to the pipeline handlers the full set of active
> > streams, and ask them to loop over them to perform per-streams
> > allocations.
> > 
> > While at it, propagate the freeBuffer() error code to the applications
> > in case of failure.
> 
> I think you should do this in a separate patch... yea I know you heard 
> it before. I'm going to keep pestering you with comments about this as 
> reviewing patches larger then ~40 lines which do more then one thing is 
> a huge pain for me ;-)

I'm fine with a single patch or two separate patches.

> > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> 
> I think you can put this patch at the beginning of the series or 
> potentially merge/post it as a separate patch as it solves a design 
> issue not strictly related to the IPU3 code.
> 
> I would drop 'allocateBuffers:' from the path subject as it's not our 
> convention to annotate using function names, how about
> 
>     libcamera: camera: Pass all active streams in allocateBuffers()

I agree with all this.

> With the subject fixed and with or without breaking the patch in two,
> 
> Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> 
> > ---
> >  src/libcamera/camera.cpp                 | 17 +++++++++--------
> >  src/libcamera/include/pipeline_handler.h |  6 ++++--
> >  src/libcamera/pipeline/ipu3/ipu3.cpp     | 13 +++++++++----
> >  src/libcamera/pipeline/uvcvideo.cpp      | 13 +++++++++----
> >  src/libcamera/pipeline/vimc.cpp          | 13 +++++++++----
> >  src/libcamera/pipeline_handler.cpp       | 11 ++++++-----
> >  6 files changed, 46 insertions(+), 27 deletions(-)
> > 
> > diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> > index bdf14b31d8ee..cb392ca3b7e7 100644
> > --- a/src/libcamera/camera.cpp
> > +++ b/src/libcamera/camera.cpp
> > @@ -647,13 +647,11 @@ int Camera::allocateBuffers()
> >  		return -EINVAL;
> >  	}
> >  
> > -	for (Stream *stream : activeStreams_) {
> > -		int ret = pipe_->allocateBuffers(this, stream);
> > -		if (ret) {
> > -			LOG(Camera, Error) << "Failed to allocate buffers";
> > -			freeBuffers();
> > -			return ret;
> > -		}
> > +	int ret = pipe_->allocateBuffers(this, activeStreams_);
> > +	if (ret) {
> > +		LOG(Camera, Error) << "Failed to allocate buffers";
> > +		freeBuffers();

This is under discussion so I won't repeat my comment here :-)

> > +		return ret;
> >  	}
> >  
> >  	state_ = CameraPrepared;
> > @@ -683,9 +681,12 @@ int Camera::freeBuffers()
> >  		 * by the V4L2 device that has allocated them.
> >  		 */
> >  		stream->bufferPool().destroyBuffers();
> > -		pipe_->freeBuffers(this, stream);
> >  	}
> >  
> > +	int ret = pipe_->freeBuffers(this, activeStreams_);
> > +	if (ret)
> > +		return ret;
> > +
> >  	state_ = CameraConfigured;

I wonder if we should set state_ to CameraConfigured even when
pipe_->freeBuffers() fails. Otherwise we won't be able to release the
camera, and we'll get more errors when closing the application (such as
stopping the camera manager with a camera still in use).

> >  
> >  	return 0;
> > diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
> > index b6cbd3bae51b..253820e8eaf8 100644
> > --- a/src/libcamera/include/pipeline_handler.h
> > +++ b/src/libcamera/include/pipeline_handler.h
> > @@ -57,8 +57,10 @@ public:
> >  	streamConfiguration(Camera *camera, const std::vector<StreamUsage> &usages) = 0;
> >  	virtual int configureStreams(Camera *camera, const CameraConfiguration &config) = 0;
> >  
> > -	virtual int allocateBuffers(Camera *camera, Stream *stream) = 0;
> > -	virtual int freeBuffers(Camera *camera, Stream *stream) = 0;
> > +	virtual int allocateBuffers(Camera *camera,
> > +				    const std::set<Stream *> &streams) = 0;
> > +	virtual int freeBuffers(Camera *camera,
> > +				const std::set<Stream *> &streams) = 0;
> >  
> >  	virtual int start(Camera *camera) = 0;
> >  	virtual void stop(Camera *camera);
> > diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > index 712e57c5a459..527213a8970a 100644
> > --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> > +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > @@ -159,8 +159,10 @@ public:
> >  	int configureStreams(Camera *camera,
> >  			     const CameraConfiguration &config) override;
> >  
> > -	int allocateBuffers(Camera *camera, Stream *stream) override;
> > -	int freeBuffers(Camera *camera, Stream *stream) override;
> > +	int allocateBuffers(Camera *camera,
> > +			    const std::set<Stream *> &streams) override;
> > +	int freeBuffers(Camera *camera,
> > +			const std::set<Stream *> &streams) override;
> >  
> >  	int start(Camera *camera) override;
> >  	void stop(Camera *camera) override;
> > @@ -378,9 +380,11 @@ int PipelineHandlerIPU3::configureStreams(Camera *camera,
> >  	return 0;
> >  }
> >  
> > -int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
> > +int PipelineHandlerIPU3::allocateBuffers(Camera *camera,
> > +					 const std::set<Stream *> &streams)
> >  {
> >  	IPU3CameraData *data = cameraData(camera);
> > +	Stream *stream = *streams.begin();
> >  	CIO2Device *cio2 = &data->cio2_;
> >  	ImgUDevice *imgu = data->imgu_;
> >  	int ret;
> > @@ -419,7 +423,8 @@ int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
> >  	return 0;
> >  }
> >  
> > -int PipelineHandlerIPU3::freeBuffers(Camera *camera, Stream *stream)
> > +int PipelineHandlerIPU3::freeBuffers(Camera *camera,
> > +				     const std::set<Stream *> &streams)
> >  {
> >  	IPU3CameraData *data = cameraData(camera);
> >  
> > diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> > index cd472cfadd86..b8f634d88b46 100644
> > --- a/src/libcamera/pipeline/uvcvideo.cpp
> > +++ b/src/libcamera/pipeline/uvcvideo.cpp
> > @@ -32,8 +32,10 @@ public:
> >  	int configureStreams(Camera *camera,
> >  			     const CameraConfiguration &config) override;
> >  
> > -	int allocateBuffers(Camera *camera, Stream *stream) override;
> > -	int freeBuffers(Camera *camera, Stream *stream) override;
> > +	int allocateBuffers(Camera *camera,
> > +			    const std::set<Stream *> &streams) override;
> > +	int freeBuffers(Camera *camera,
> > +			const std::set<Stream *> &streams) override;
> >  
> >  	int start(Camera *camera) override;
> >  	void stop(Camera *camera) override;
> > @@ -127,9 +129,11 @@ int PipelineHandlerUVC::configureStreams(Camera *camera,
> >  	return 0;
> >  }
> >  
> > -int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
> > +int PipelineHandlerUVC::allocateBuffers(Camera *camera,
> > +					const std::set<Stream *> &streams)
> >  {
> >  	UVCCameraData *data = cameraData(camera);
> > +	Stream *stream = *streams.begin();
> >  	const StreamConfiguration &cfg = stream->configuration();
> >  
> >  	LOG(UVC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
> > @@ -137,7 +141,8 @@ int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
> >  	return data->video_->exportBuffers(&stream->bufferPool());
> >  }
> >  
> > -int PipelineHandlerUVC::freeBuffers(Camera *camera, Stream *stream)
> > +int PipelineHandlerUVC::freeBuffers(Camera *camera,
> > +				    const std::set<Stream *> &streams)
> >  {
> >  	UVCCameraData *data = cameraData(camera);
> >  	return data->video_->releaseBuffers();
> > diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> > index c8bbe2a19847..22449e47bc2d 100644
> > --- a/src/libcamera/pipeline/vimc.cpp
> > +++ b/src/libcamera/pipeline/vimc.cpp
> > @@ -32,8 +32,10 @@ public:
> >  	int configureStreams(Camera *camera,
> >  			     const CameraConfiguration &config) override;
> >  
> > -	int allocateBuffers(Camera *camera, Stream *stream) override;
> > -	int freeBuffers(Camera *camera, Stream *stream) override;
> > +	int allocateBuffers(Camera *camera,
> > +			    const std::set<Stream *> &streams) override;
> > +	int freeBuffers(Camera *camera,
> > +			const std::set<Stream *> &streams) override;
> >  
> >  	int start(Camera *camera) override;
> >  	void stop(Camera *camera) override;
> > @@ -127,9 +129,11 @@ int PipelineHandlerVimc::configureStreams(Camera *camera,
> >  	return 0;
> >  }
> >  
> > -int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
> > +int PipelineHandlerVimc::allocateBuffers(Camera *camera,
> > +					 const std::set<Stream *> &streams)
> >  {
> >  	VimcCameraData *data = cameraData(camera);
> > +	Stream *stream = *streams.begin();
> >  	const StreamConfiguration &cfg = stream->configuration();
> >  
> >  	LOG(VIMC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
> > @@ -137,7 +141,8 @@ int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
> >  	return data->video_->exportBuffers(&stream->bufferPool());
> >  }
> >  
> > -int PipelineHandlerVimc::freeBuffers(Camera *camera, Stream *stream)
> > +int PipelineHandlerVimc::freeBuffers(Camera *camera,
> > +				     const std::set<Stream *> &streams)
> >  {
> >  	VimcCameraData *data = cameraData(camera);
> >  	return data->video_->releaseBuffers();
> > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > index 43550c0e0210..911d08448e69 100644
> > --- a/src/libcamera/pipeline_handler.cpp
> > +++ b/src/libcamera/pipeline_handler.cpp
> > @@ -193,10 +193,11 @@ PipelineHandler::~PipelineHandler()
> >   * \fn PipelineHandler::allocateBuffers()
> >   * \brief Allocate buffers for a stream
> >   * \param[in] camera The camera the \a stream belongs to
> > - * \param[in] stream The stream to allocate buffers for
> > + * \param[in] streams The set of streams to allocate buffers for
> >   *
> > - * This method allocates buffers internally in the pipeline handler and
> > - * associates them with the stream's buffer pool.
> > + * This method allocates buffers internally in the pipeline handler for each
> > + * stream in the \a streams buffer set, and associates them with the stream's
> > + * buffer pool.
> >   *
> >   * The intended caller of this method is the Camera class.
> >   *
> > @@ -207,9 +208,9 @@ PipelineHandler::~PipelineHandler()
> >   * \fn PipelineHandler::freeBuffers()
> >   * \brief Free all buffers associated with a stream
> >   * \param[in] camera The camera the \a stream belongs to
> > - * \param[in] stream The stream to free buffers from
> > + * \param[in] streams The set of streams to free buffers from

s/from/for/

With the small comments addressed, and the freeBuffers() issue solved,

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> >   *
> > - * After a capture session has been stopped all buffers associated with the
> > + * After a capture session has been stopped all buffers associated with each
> >   * stream shall be freed.
> >   *
> >   * The intended caller of this method is the Camera class.
Jacopo Mondi April 15, 2019, 2:50 p.m. UTC | #3
Hi Laurent,

On Mon, Apr 15, 2019 at 02:48:40PM +0300, Laurent Pinchart wrote:
> Hello,
>
> On Sun, Apr 14, 2019 at 09:53:58PM +0200, Niklas Söderlund wrote:
> > On 2019-04-09 21:25:39 +0200, Jacopo Mondi wrote:
> > > Pipeline handlers might need to perform allocation of internal buffers,
> > > setup operations, or simple sanity check before going into the
> > > per-stream buffer allocation.
> > >
> > > As of now, PipelineHandler::allocateBuffers() is called once for each
> > > active stream, leaving no space for stream-independent configuration.
> > >
> > > Change this by providing to the pipeline handlers the full set of active
> > > streams, and ask them to loop over them to perform per-streams
> > > allocations.
> > >
> > > While at it, propagate the freeBuffer() error code to the applications
> > > in case of failure.
> >
> > I think you should do this in a separate patch... yea I know you heard
> > it before. I'm going to keep pestering you with comments about this as
> > reviewing patches larger then ~40 lines which do more then one thing is
> > a huge pain for me ;-)
>
> I'm fine with a single patch or two separate patches.
>
> > > Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
> >
> > I think you can put this patch at the beginning of the series or
> > potentially merge/post it as a separate patch as it solves a design
> > issue not strictly related to the IPU3 code.
> >
> > I would drop 'allocateBuffers:' from the path subject as it's not our
> > convention to annotate using function names, how about
> >
> >     libcamera: camera: Pass all active streams in allocateBuffers()
>
> I agree with all this.
>
> > With the subject fixed and with or without breaking the patch in two,
> >
> > Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
> >
> > > ---
> > >  src/libcamera/camera.cpp                 | 17 +++++++++--------
> > >  src/libcamera/include/pipeline_handler.h |  6 ++++--
> > >  src/libcamera/pipeline/ipu3/ipu3.cpp     | 13 +++++++++----
> > >  src/libcamera/pipeline/uvcvideo.cpp      | 13 +++++++++----
> > >  src/libcamera/pipeline/vimc.cpp          | 13 +++++++++----
> > >  src/libcamera/pipeline_handler.cpp       | 11 ++++++-----
> > >  6 files changed, 46 insertions(+), 27 deletions(-)
> > >
> > > diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> > > index bdf14b31d8ee..cb392ca3b7e7 100644
> > > --- a/src/libcamera/camera.cpp
> > > +++ b/src/libcamera/camera.cpp
> > > @@ -647,13 +647,11 @@ int Camera::allocateBuffers()
> > >  		return -EINVAL;
> > >  	}
> > >
> > > -	for (Stream *stream : activeStreams_) {
> > > -		int ret = pipe_->allocateBuffers(this, stream);
> > > -		if (ret) {
> > > -			LOG(Camera, Error) << "Failed to allocate buffers";
> > > -			freeBuffers();
> > > -			return ret;
> > > -		}
> > > +	int ret = pipe_->allocateBuffers(this, activeStreams_);
> > > +	if (ret) {
> > > +		LOG(Camera, Error) << "Failed to allocate buffers";
> > > +		freeBuffers();
>
> This is under discussion so I won't repeat my comment here :-)
>
> > > +		return ret;
> > >  	}
> > >
> > >  	state_ = CameraPrepared;
> > > @@ -683,9 +681,12 @@ int Camera::freeBuffers()
> > >  		 * by the V4L2 device that has allocated them.
> > >  		 */
> > >  		stream->bufferPool().destroyBuffers();
> > > -		pipe_->freeBuffers(this, stream);
> > >  	}
> > >
> > > +	int ret = pipe_->freeBuffers(this, activeStreams_);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > >  	state_ = CameraConfigured;
>
> I wonder if we should set state_ to CameraConfigured even when
> pipe_->freeBuffers() fails. Otherwise we won't be able to release the
> camera, and we'll get more errors when closing the application (such as
> stopping the camera manager with a camera still in use).
>

Good point... I should only propagate the error up but not return
eralier then. Thanks.

> > >
> > >  	return 0;
> > > diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
> > > index b6cbd3bae51b..253820e8eaf8 100644
> > > --- a/src/libcamera/include/pipeline_handler.h
> > > +++ b/src/libcamera/include/pipeline_handler.h
> > > @@ -57,8 +57,10 @@ public:
> > >  	streamConfiguration(Camera *camera, const std::vector<StreamUsage> &usages) = 0;
> > >  	virtual int configureStreams(Camera *camera, const CameraConfiguration &config) = 0;
> > >
> > > -	virtual int allocateBuffers(Camera *camera, Stream *stream) = 0;
> > > -	virtual int freeBuffers(Camera *camera, Stream *stream) = 0;
> > > +	virtual int allocateBuffers(Camera *camera,
> > > +				    const std::set<Stream *> &streams) = 0;
> > > +	virtual int freeBuffers(Camera *camera,
> > > +				const std::set<Stream *> &streams) = 0;
> > >
> > >  	virtual int start(Camera *camera) = 0;
> > >  	virtual void stop(Camera *camera);
> > > diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > index 712e57c5a459..527213a8970a 100644
> > > --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > @@ -159,8 +159,10 @@ public:
> > >  	int configureStreams(Camera *camera,
> > >  			     const CameraConfiguration &config) override;
> > >
> > > -	int allocateBuffers(Camera *camera, Stream *stream) override;
> > > -	int freeBuffers(Camera *camera, Stream *stream) override;
> > > +	int allocateBuffers(Camera *camera,
> > > +			    const std::set<Stream *> &streams) override;
> > > +	int freeBuffers(Camera *camera,
> > > +			const std::set<Stream *> &streams) override;
> > >
> > >  	int start(Camera *camera) override;
> > >  	void stop(Camera *camera) override;
> > > @@ -378,9 +380,11 @@ int PipelineHandlerIPU3::configureStreams(Camera *camera,
> > >  	return 0;
> > >  }
> > >
> > > -int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
> > > +int PipelineHandlerIPU3::allocateBuffers(Camera *camera,
> > > +					 const std::set<Stream *> &streams)
> > >  {
> > >  	IPU3CameraData *data = cameraData(camera);
> > > +	Stream *stream = *streams.begin();
> > >  	CIO2Device *cio2 = &data->cio2_;
> > >  	ImgUDevice *imgu = data->imgu_;
> > >  	int ret;
> > > @@ -419,7 +423,8 @@ int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
> > >  	return 0;
> > >  }
> > >
> > > -int PipelineHandlerIPU3::freeBuffers(Camera *camera, Stream *stream)
> > > +int PipelineHandlerIPU3::freeBuffers(Camera *camera,
> > > +				     const std::set<Stream *> &streams)
> > >  {
> > >  	IPU3CameraData *data = cameraData(camera);
> > >
> > > diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
> > > index cd472cfadd86..b8f634d88b46 100644
> > > --- a/src/libcamera/pipeline/uvcvideo.cpp
> > > +++ b/src/libcamera/pipeline/uvcvideo.cpp
> > > @@ -32,8 +32,10 @@ public:
> > >  	int configureStreams(Camera *camera,
> > >  			     const CameraConfiguration &config) override;
> > >
> > > -	int allocateBuffers(Camera *camera, Stream *stream) override;
> > > -	int freeBuffers(Camera *camera, Stream *stream) override;
> > > +	int allocateBuffers(Camera *camera,
> > > +			    const std::set<Stream *> &streams) override;
> > > +	int freeBuffers(Camera *camera,
> > > +			const std::set<Stream *> &streams) override;
> > >
> > >  	int start(Camera *camera) override;
> > >  	void stop(Camera *camera) override;
> > > @@ -127,9 +129,11 @@ int PipelineHandlerUVC::configureStreams(Camera *camera,
> > >  	return 0;
> > >  }
> > >
> > > -int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
> > > +int PipelineHandlerUVC::allocateBuffers(Camera *camera,
> > > +					const std::set<Stream *> &streams)
> > >  {
> > >  	UVCCameraData *data = cameraData(camera);
> > > +	Stream *stream = *streams.begin();
> > >  	const StreamConfiguration &cfg = stream->configuration();
> > >
> > >  	LOG(UVC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
> > > @@ -137,7 +141,8 @@ int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
> > >  	return data->video_->exportBuffers(&stream->bufferPool());
> > >  }
> > >
> > > -int PipelineHandlerUVC::freeBuffers(Camera *camera, Stream *stream)
> > > +int PipelineHandlerUVC::freeBuffers(Camera *camera,
> > > +				    const std::set<Stream *> &streams)
> > >  {
> > >  	UVCCameraData *data = cameraData(camera);
> > >  	return data->video_->releaseBuffers();
> > > diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
> > > index c8bbe2a19847..22449e47bc2d 100644
> > > --- a/src/libcamera/pipeline/vimc.cpp
> > > +++ b/src/libcamera/pipeline/vimc.cpp
> > > @@ -32,8 +32,10 @@ public:
> > >  	int configureStreams(Camera *camera,
> > >  			     const CameraConfiguration &config) override;
> > >
> > > -	int allocateBuffers(Camera *camera, Stream *stream) override;
> > > -	int freeBuffers(Camera *camera, Stream *stream) override;
> > > +	int allocateBuffers(Camera *camera,
> > > +			    const std::set<Stream *> &streams) override;
> > > +	int freeBuffers(Camera *camera,
> > > +			const std::set<Stream *> &streams) override;
> > >
> > >  	int start(Camera *camera) override;
> > >  	void stop(Camera *camera) override;
> > > @@ -127,9 +129,11 @@ int PipelineHandlerVimc::configureStreams(Camera *camera,
> > >  	return 0;
> > >  }
> > >
> > > -int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
> > > +int PipelineHandlerVimc::allocateBuffers(Camera *camera,
> > > +					 const std::set<Stream *> &streams)
> > >  {
> > >  	VimcCameraData *data = cameraData(camera);
> > > +	Stream *stream = *streams.begin();
> > >  	const StreamConfiguration &cfg = stream->configuration();
> > >
> > >  	LOG(VIMC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
> > > @@ -137,7 +141,8 @@ int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
> > >  	return data->video_->exportBuffers(&stream->bufferPool());
> > >  }
> > >
> > > -int PipelineHandlerVimc::freeBuffers(Camera *camera, Stream *stream)
> > > +int PipelineHandlerVimc::freeBuffers(Camera *camera,
> > > +				     const std::set<Stream *> &streams)
> > >  {
> > >  	VimcCameraData *data = cameraData(camera);
> > >  	return data->video_->releaseBuffers();
> > > diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
> > > index 43550c0e0210..911d08448e69 100644
> > > --- a/src/libcamera/pipeline_handler.cpp
> > > +++ b/src/libcamera/pipeline_handler.cpp
> > > @@ -193,10 +193,11 @@ PipelineHandler::~PipelineHandler()
> > >   * \fn PipelineHandler::allocateBuffers()
> > >   * \brief Allocate buffers for a stream
> > >   * \param[in] camera The camera the \a stream belongs to
> > > - * \param[in] stream The stream to allocate buffers for
> > > + * \param[in] streams The set of streams to allocate buffers for
> > >   *
> > > - * This method allocates buffers internally in the pipeline handler and
> > > - * associates them with the stream's buffer pool.
> > > + * This method allocates buffers internally in the pipeline handler for each
> > > + * stream in the \a streams buffer set, and associates them with the stream's
> > > + * buffer pool.
> > >   *
> > >   * The intended caller of this method is the Camera class.
> > >   *
> > > @@ -207,9 +208,9 @@ PipelineHandler::~PipelineHandler()
> > >   * \fn PipelineHandler::freeBuffers()
> > >   * \brief Free all buffers associated with a stream
> > >   * \param[in] camera The camera the \a stream belongs to
> > > - * \param[in] stream The stream to free buffers from
> > > + * \param[in] streams The set of streams to free buffers from
>
> s/from/for/
>
> With the small comments addressed, and the freeBuffers() issue solved,
>

I will send separate patches to:
1) propagate the freeBuffers() error up
2) remove freeBuffers() call in allocateBuffers() error path
3) pass the active stream vector to allocate/free

Thanks
  j

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>
> > >   *
> > > - * After a capture session has been stopped all buffers associated with the
> > > + * After a capture session has been stopped all buffers associated with each
> > >   * stream shall be freed.
> > >   *
> > >   * The intended caller of this method is the Camera class.
>
> --
> Regards,
>
> Laurent Pinchart

Patch

diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index bdf14b31d8ee..cb392ca3b7e7 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -647,13 +647,11 @@  int Camera::allocateBuffers()
 		return -EINVAL;
 	}
 
-	for (Stream *stream : activeStreams_) {
-		int ret = pipe_->allocateBuffers(this, stream);
-		if (ret) {
-			LOG(Camera, Error) << "Failed to allocate buffers";
-			freeBuffers();
-			return ret;
-		}
+	int ret = pipe_->allocateBuffers(this, activeStreams_);
+	if (ret) {
+		LOG(Camera, Error) << "Failed to allocate buffers";
+		freeBuffers();
+		return ret;
 	}
 
 	state_ = CameraPrepared;
@@ -683,9 +681,12 @@  int Camera::freeBuffers()
 		 * by the V4L2 device that has allocated them.
 		 */
 		stream->bufferPool().destroyBuffers();
-		pipe_->freeBuffers(this, stream);
 	}
 
+	int ret = pipe_->freeBuffers(this, activeStreams_);
+	if (ret)
+		return ret;
+
 	state_ = CameraConfigured;
 
 	return 0;
diff --git a/src/libcamera/include/pipeline_handler.h b/src/libcamera/include/pipeline_handler.h
index b6cbd3bae51b..253820e8eaf8 100644
--- a/src/libcamera/include/pipeline_handler.h
+++ b/src/libcamera/include/pipeline_handler.h
@@ -57,8 +57,10 @@  public:
 	streamConfiguration(Camera *camera, const std::vector<StreamUsage> &usages) = 0;
 	virtual int configureStreams(Camera *camera, const CameraConfiguration &config) = 0;
 
-	virtual int allocateBuffers(Camera *camera, Stream *stream) = 0;
-	virtual int freeBuffers(Camera *camera, Stream *stream) = 0;
+	virtual int allocateBuffers(Camera *camera,
+				    const std::set<Stream *> &streams) = 0;
+	virtual int freeBuffers(Camera *camera,
+				const std::set<Stream *> &streams) = 0;
 
 	virtual int start(Camera *camera) = 0;
 	virtual void stop(Camera *camera);
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 712e57c5a459..527213a8970a 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -159,8 +159,10 @@  public:
 	int configureStreams(Camera *camera,
 			     const CameraConfiguration &config) override;
 
-	int allocateBuffers(Camera *camera, Stream *stream) override;
-	int freeBuffers(Camera *camera, Stream *stream) override;
+	int allocateBuffers(Camera *camera,
+			    const std::set<Stream *> &streams) override;
+	int freeBuffers(Camera *camera,
+			const std::set<Stream *> &streams) override;
 
 	int start(Camera *camera) override;
 	void stop(Camera *camera) override;
@@ -378,9 +380,11 @@  int PipelineHandlerIPU3::configureStreams(Camera *camera,
 	return 0;
 }
 
-int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
+int PipelineHandlerIPU3::allocateBuffers(Camera *camera,
+					 const std::set<Stream *> &streams)
 {
 	IPU3CameraData *data = cameraData(camera);
+	Stream *stream = *streams.begin();
 	CIO2Device *cio2 = &data->cio2_;
 	ImgUDevice *imgu = data->imgu_;
 	int ret;
@@ -419,7 +423,8 @@  int PipelineHandlerIPU3::allocateBuffers(Camera *camera, Stream *stream)
 	return 0;
 }
 
-int PipelineHandlerIPU3::freeBuffers(Camera *camera, Stream *stream)
+int PipelineHandlerIPU3::freeBuffers(Camera *camera,
+				     const std::set<Stream *> &streams)
 {
 	IPU3CameraData *data = cameraData(camera);
 
diff --git a/src/libcamera/pipeline/uvcvideo.cpp b/src/libcamera/pipeline/uvcvideo.cpp
index cd472cfadd86..b8f634d88b46 100644
--- a/src/libcamera/pipeline/uvcvideo.cpp
+++ b/src/libcamera/pipeline/uvcvideo.cpp
@@ -32,8 +32,10 @@  public:
 	int configureStreams(Camera *camera,
 			     const CameraConfiguration &config) override;
 
-	int allocateBuffers(Camera *camera, Stream *stream) override;
-	int freeBuffers(Camera *camera, Stream *stream) override;
+	int allocateBuffers(Camera *camera,
+			    const std::set<Stream *> &streams) override;
+	int freeBuffers(Camera *camera,
+			const std::set<Stream *> &streams) override;
 
 	int start(Camera *camera) override;
 	void stop(Camera *camera) override;
@@ -127,9 +129,11 @@  int PipelineHandlerUVC::configureStreams(Camera *camera,
 	return 0;
 }
 
-int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
+int PipelineHandlerUVC::allocateBuffers(Camera *camera,
+					const std::set<Stream *> &streams)
 {
 	UVCCameraData *data = cameraData(camera);
+	Stream *stream = *streams.begin();
 	const StreamConfiguration &cfg = stream->configuration();
 
 	LOG(UVC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
@@ -137,7 +141,8 @@  int PipelineHandlerUVC::allocateBuffers(Camera *camera, Stream *stream)
 	return data->video_->exportBuffers(&stream->bufferPool());
 }
 
-int PipelineHandlerUVC::freeBuffers(Camera *camera, Stream *stream)
+int PipelineHandlerUVC::freeBuffers(Camera *camera,
+				    const std::set<Stream *> &streams)
 {
 	UVCCameraData *data = cameraData(camera);
 	return data->video_->releaseBuffers();
diff --git a/src/libcamera/pipeline/vimc.cpp b/src/libcamera/pipeline/vimc.cpp
index c8bbe2a19847..22449e47bc2d 100644
--- a/src/libcamera/pipeline/vimc.cpp
+++ b/src/libcamera/pipeline/vimc.cpp
@@ -32,8 +32,10 @@  public:
 	int configureStreams(Camera *camera,
 			     const CameraConfiguration &config) override;
 
-	int allocateBuffers(Camera *camera, Stream *stream) override;
-	int freeBuffers(Camera *camera, Stream *stream) override;
+	int allocateBuffers(Camera *camera,
+			    const std::set<Stream *> &streams) override;
+	int freeBuffers(Camera *camera,
+			const std::set<Stream *> &streams) override;
 
 	int start(Camera *camera) override;
 	void stop(Camera *camera) override;
@@ -127,9 +129,11 @@  int PipelineHandlerVimc::configureStreams(Camera *camera,
 	return 0;
 }
 
-int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
+int PipelineHandlerVimc::allocateBuffers(Camera *camera,
+					 const std::set<Stream *> &streams)
 {
 	VimcCameraData *data = cameraData(camera);
+	Stream *stream = *streams.begin();
 	const StreamConfiguration &cfg = stream->configuration();
 
 	LOG(VIMC, Debug) << "Requesting " << cfg.bufferCount << " buffers";
@@ -137,7 +141,8 @@  int PipelineHandlerVimc::allocateBuffers(Camera *camera, Stream *stream)
 	return data->video_->exportBuffers(&stream->bufferPool());
 }
 
-int PipelineHandlerVimc::freeBuffers(Camera *camera, Stream *stream)
+int PipelineHandlerVimc::freeBuffers(Camera *camera,
+				     const std::set<Stream *> &streams)
 {
 	VimcCameraData *data = cameraData(camera);
 	return data->video_->releaseBuffers();
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 43550c0e0210..911d08448e69 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -193,10 +193,11 @@  PipelineHandler::~PipelineHandler()
  * \fn PipelineHandler::allocateBuffers()
  * \brief Allocate buffers for a stream
  * \param[in] camera The camera the \a stream belongs to
- * \param[in] stream The stream to allocate buffers for
+ * \param[in] streams The set of streams to allocate buffers for
  *
- * This method allocates buffers internally in the pipeline handler and
- * associates them with the stream's buffer pool.
+ * This method allocates buffers internally in the pipeline handler for each
+ * stream in the \a streams buffer set, and associates them with the stream's
+ * buffer pool.
  *
  * The intended caller of this method is the Camera class.
  *
@@ -207,9 +208,9 @@  PipelineHandler::~PipelineHandler()
  * \fn PipelineHandler::freeBuffers()
  * \brief Free all buffers associated with a stream
  * \param[in] camera The camera the \a stream belongs to
- * \param[in] stream The stream to free buffers from
+ * \param[in] streams The set of streams to free buffers from
  *
- * After a capture session has been stopped all buffers associated with the
+ * After a capture session has been stopped all buffers associated with each
  * stream shall be freed.
  *
  * The intended caller of this method is the Camera class.