[libcamera-devel] [PATCH v3 6/6] libcamera: camera: extend camera object to support configuration of streams

[Niklas Söderlund]

Hi Laurent,

Thanks for your feedback.

On 2019-01-28 02:35:23 +0200, Laurent Pinchart wrote:
> Hi Niklas,
> 
> Thank you for the patch.
> 
> On Sun, Jan 27, 2019 at 01:22:08AM +0100, Niklas Söderlund wrote:
> > Extend the camera to support reading and configuring of formats for
> 
> s/of formats/formats/

Thanks.

> 
> > groups of streams. The implementation in the Camera are minimalistic as
> > the heavy lifting are done by the pipeline handler implementations.
> > 
> > The most important functionality the camera provides in this context is
> > validation of data structures passed to it from the application and
> > access control to the pipeline handler.
> > 
> > Signed-off-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> > ---
> >  include/libcamera/camera.h |  4 +++
> >  src/libcamera/camera.cpp   | 68 ++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 72 insertions(+)
> > 
> > diff --git a/include/libcamera/camera.h b/include/libcamera/camera.h
> > index 786d4d7d66bed5b2..798fee2487940208 100644
> > --- a/include/libcamera/camera.h
> > +++ b/include/libcamera/camera.h
> > @@ -7,6 +7,7 @@
> >  #ifndef __LIBCAMERA_CAMERA_H__
> >  #define __LIBCAMERA_CAMERA_H__
> >  
> > +#include <map>
> >  #include <memory>
> >  #include <string>
> >  
> > @@ -16,6 +17,7 @@ namespace libcamera {
> >  
> >  class PipelineHandler;
> >  class Stream;
> > +class StreamConfiguration;
> >  
> >  class Camera final
> >  {
> > @@ -35,6 +37,8 @@ public:
> >  	void release();
> >  
> >  	std::vector<Stream> streams() const;
> > +	std::map<unsigned int, StreamConfiguration> streamConfiguration(const std::vector<Stream> &streams) const;
> > +	int configureStreams(std::map<unsigned int, StreamConfiguration> &config);
> >  
> >  private:
> >  	Camera(PipelineHandler *pipe, const std::string &name);
> > diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
> > index 3b2c00d0a4bb45d1..e41143972b0b537a 100644
> > --- a/src/libcamera/camera.cpp
> > +++ b/src/libcamera/camera.cpp
> > @@ -211,4 +211,72 @@ std::vector<Stream> Camera::streams() const
> >  	return streams_;
> >  }
> >  
> > +/**
> > + * \brief Retrieve a group of stream configurations
> > + * \param[in] streams A map of stream IDs and configurations to setup
> > + *
> > + * Retrieve the camera's configuration for a specified group of streams. The
> > + * caller can specify which of the camera's streams to retrieve configuration
> > + * from by populating \a streams.
> > + *
> > + * The easiest way to populate the array of streams to fetch configuration from
> > + * is to first retrieve the camera's full array of stream by with streams() and
> > + * then potentially trim it down to only contain the streams the caller
> > + * are interested in.
> > + *
> > + * \return A map of successfully retrieved stream IDs and configurations or an
> > + * empty list on error.
> > + */
> > +std::map<unsigned int, StreamConfiguration>
> > +Camera::streamConfiguration(const std::vector<Stream> &streams) const
> > +{
> > +	std::map<unsigned int, StreamConfiguration> config;
> > +
> > +	if (disconnected_ || !streams.size())
> > +		return config;
> > +
> > +	for (const Stream &stream : streams)
> > +		if (!haveStreamID(stream.id()))
> > +			return config;
> > +
> > +	return pipe_->streamConfiguration(this, streams);
> > +}
> > +
> > +/**
> > + * \brief Configure the camera's streams prior to capture
> > + * \param[in] config A map of stream IDs and configurations to setup
> > + *
> > + * Prior to starting capture, the camera must be configured to select a
> > + * group of streams to be involved in the capture and their configuration.
> > + * The caller specify which streams are to be involved and their configuration
> 
> s/specify/specifies/
> 
> > + * by populating \a config.
> > + *
> > + * The easiest way to populate the array of config is to fetch an initial
> > + * configuration from the camera with streamConfiguration() and then change the
> > + * parameters to fit the callers need and once all the streams parameters are
> 
> s/callers need/caller's needs/
> 
> > + * configured hand that over to configureStreams() to actually setup the camera.
> > + *
> > + * Exclusive access to the camera shall be ensured by a call to acquire() prior
> > + * to calling this function, otherwise an -EACCES error is be returned.
> 
> You should document that -ENODEV will be returned in case the camera is
> disconnected, and -EINVAL if the configuration isn't valid.

Good point.

> 
> > + *
> > + * \return 0 on success or a negative error code on error.
> > + */
> > +int Camera::configureStreams(std::map<unsigned int, StreamConfiguration> &config)
> > +{
> > +	if (disconnected_)
> > +		return -ENODEV;
> > +
> > +	if (!acquired_)
> > +		return -EACCES;
> > +
> > +	if (!config.size())
> > +		return -EINVAL;
> > +
> > +	for (const auto &pair : config)
> > +		if (!haveStreamID(pair.first))
> > +			return -EINVAL;
> 
> Could we make this error impossible by indexing the map on a Stream
> pointer ?

I had a try at this for v4, it looks much better. Thanks for the 
suggestion.

> 
> > +	return pipe_->configureStreams(this, config);
> > +}
> > +
> >  } /* namespace libcamera */
> 
> -- 
> Regards,
> 
> Laurent Pinchart

-- 
Regards,
Niklas Söderlund