[libcamera-devel] [PATCH 2/2] libcamera: ipu3: Create CIO2 V4L2 devices

[Laurent Pinchart]

Hi Jacopo,

On Thu, Jan 24, 2019 at 08:33:00PM +0100, Jacopo Mondi wrote:
> On Thu, Jan 24, 2019 at 08:06:30PM +0100, Niklas Söderlund wrote:
> > On 2019-01-24 12:30:20 +0100, Jacopo Mondi wrote:
> >> Create V4L2 devices for the CIO2 capture video nodes and associate them
> >> with the camera they are part of.
> >>
> >> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> >> ---
> >>  src/libcamera/pipeline/ipu3/ipu3.cpp | 50 ++++++++++++++++++++++++++++
> >>  1 file changed, 50 insertions(+)
> >>
> >> diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
> >> index 8cbc10a..9f5a40f 100644
> >> --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> >> +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> >> @@ -15,6 +15,8 @@
> >>  #include "log.h"
> >>  #include "media_device.h"
> >>  #include "pipeline_handler.h"
> >> +#include "utils.h"
> >> +#include "v4l2_device.h"
> >>
> >>  namespace libcamera {
> >>
> >> @@ -29,9 +31,19 @@ public:
> >>  	bool match(CameraManager *manager, DeviceEnumerator *enumerator);
> >>
> >>  private:
> >> +	class IPU3CameraData : public CameraData
> >> +	{
> >> +	public:
> >> +		IPU3CameraData()
> >> +			: dev_(nullptr) { }
> >> +		~IPU3CameraData() { delete dev_; }
> >> +		V4L2Device *dev_;
> >> +	};
> >> +
> >>  	MediaDevice *cio2_;
> >>  	MediaDevice *imgu_;
> >>
> >> +	V4L2Device *createVideoDevice(unsigned int id);
> >>  	void registerCameras(CameraManager *manager);
> >>  };
> >>
> >> @@ -122,6 +134,24 @@ error_release_mdev:
> >>  	return false;
> >>  }
> >>
> >> +/* Create video devices for the CIO2 unit associated with a camera. */
> >> +V4L2Device *PipelineHandlerIPU3::createVideoDevice(unsigned int id)
> >> +{
> >> +	std::string cio2Name = "ipu3-cio2 " + std::to_string(id);
> >> +	MediaEntity *cio2 = cio2_->getEntityByName(cio2Name);
> >> +	if (!cio2)
> >> +		return nullptr;
> >> +
> >> +	V4L2Device *dev = new V4L2Device(*cio2);
> >> +	if (dev->open()) {
> >> +		delete dev;
> >> +		return nullptr;
> >> +	}
> >> +	dev->close();
> >> +
> >> +	return dev;
> >> +}
> >> +
> >>  /*
> >>   * Cameras are created associating an image sensor (represented by a
> >>   * media entity with function MEDIA_ENT_F_CAM_SENSOR) to one of the four
> >> @@ -172,6 +202,26 @@ void PipelineHandlerIPU3::registerCameras(CameraManager *manager)
> >>
> >>  		std::string cameraName = sensor->name() + " " + std::to_string(id);
> >>  		std::shared_ptr<Camera> camera = Camera::create(cameraName);
> >> +
> >> +		setCameraData(camera.get(),
> >> +			      std::move(utils::make_unique<IPU3CameraData>()));
> >> +		IPU3CameraData *data =
> >> +			reinterpret_cast<IPU3CameraData *>(cameraData(camera.get()));
> >
> > I'm not saying this is not needed, only that it looks a bit complex to
> > my feeble mind. Could you educate me why the following would not work?
> >
> >     IPU3CameraData *data = new IPU3CameraData();
> >     data->dev_ = videoDev;
> >
> >     setCameraData(camera.get(), data);
> 
> setCameraData wants a unique_ptr. On the reason why we're passing it
> by value (hence the std::move() ) instead than by reference and move()
> inside the function see the discussion on v1. Basically, it makes
> clear that after setCameraData() the local reference it's not
> valid anymore.
> 
> That said, I could indeed have created a unique_ptr<> from an already
> existing reference, instead of using std::make_unique.
> 
> What I have now looks like the following:
> 
> 		V4L2Device *videoDev = createVideoDevice(id);
> 		if (!videoDev) {
> 			LOG(IPU3, Error)
> 				<< "Failed to register camera["
> 				<< numCameras << "] \"" << cameraName << "\"";
> 			continue;
> 		}
> 
> 		IPU3CameraData *data = new IPU3CameraData(*videoDev);
> 		setCameraData(camera.get(),
> 			      std::move(std::unique_ptr<IPU3CameraData>(data)));
> 		manager->addCamera(std::move(camera));
> 
> Which is in my opinion nicer and equally safe. Thanks a lot for pointing
> this out. Is it any better?

How about

		std::unique_ptr<IPU3CameraData> data = utils::make_unique<IPU3CameraData>();
 		data->dev_ = createVideoDevice(id);
 		if (!data->dev_) {
 			LOG(IPU3, Error)
 				<< "Failed to register camera["
 				<< numCameras << "] \"" << cameraName << "\"";
 			continue;
 		}
 
 		setCameraData(camera.get(), std::move(data));
 		manager->addCamera(std::move(camera));

> > Apart from this I think this commit looks good.
> >
> >> +
> >> +		/*
> >> +		 * If V4L2 device creation fails, the Camera instance won't be
> >> +		 * registered. The 'camera' shared pointer goes out of scope
> >> +		 * and deletes the Camera it manages.
> >> +		 */
> >> +		V4L2Device *videoDev = createVideoDevice(id);
> >> +		if (!videoDev) {
> >> +			LOG(IPU3, Error)
> >> +				<< "Failed to register camera["
> >> +				<< numCameras << "] \"" << cameraName << "\"";
> >> +			continue;
> >> +		}
> >> +
> >> +		data->dev_ = videoDev;
> >>  		manager->addCamera(std::move(camera));
> >>
> >>  		LOG(IPU3, Info)

-- 
Regards,

Laurent Pinchart