[libcamera-devel] [PATCH 2/5] libcamera: ipu3: Return video output default configuration

[Jacopo Mondi]

Hi Jerry,
        thanks for your comment

On Fri, Feb 22, 2019 at 02:30:09AM +0000, Hu, Jerry W wrote:
> Hi,
>
> May I know why hard coded the width and height?
> > > +	config.width = 2560;
> > > +	config.height = 1920;
> > > +	config.pixelFormat = V4L2_PIX_FMT_NV12;
>


This happens in the 'streamConfiguration()' methods, which
applications use to obtain a known good default resolution and image
format the camera can provide. In this case I've selected 2560x1920
NV12 format as "default" for the single stream the IPU3 camera
provides at the moment.

Once application receives a known default format it is then free to
change any parameter of that, and provide it to libcamera using the
Camera::configureStreams() methods. The Camera instance will pass the
configurations to the pipeline handlers, that wil try to apply it to
the hardware.

To sum up: we need to provide to applications a default configuration
suitable for the hardware, and that's why we hardcode those values
here. Starting from that default configuration, applications can
configure streams with the desired width, height and pixel format and
ask libcamera to apply it to the hardware.

Does this clarify your concerns?
Thanks
   j

> Thanks,
> -Jerry
>
> -----Original Message-----
> From: libcamera-devel [mailto:libcamera-devel-bounces at lists.libcamera.org] On Behalf Of Jacopo Mondi
> Sent: Friday, February 22, 2019 12:21 AM
> To: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> Cc: libcamera-devel at lists.libcamera.org
> Subject: Re: [libcamera-devel] [PATCH 2/5] libcamera: ipu3: Return video output default configuration
>
> Hi Niklas,
>
> On Thu, Feb 21, 2019 at 04:58:35PM +0100, Niklas Söderlund wrote:
> > Hi Jacopo,
> >
> > Thanks for your patch.
> >
> > On 2019-02-20 14:17:54 +0100, Jacopo Mondi wrote:
> > > Return default configuration for the output stream produced by the
> > > imgu 'output' video node.
> > >
> > > Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> > > ---
> > >  src/libcamera/pipeline/ipu3/ipu3.cpp | 16 +++-------------
> > >  1 file changed, 3 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > index 9694d0ce51ab..9065073913a2 100644
> > > --- a/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > +++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
> > > @@ -99,21 +99,11 @@ PipelineHandlerIPU3::streamConfiguration(Camera
> > > *camera,  {
> > >  	IPU3CameraData *data = cameraData(camera);
> > >  	std::map<Stream *, StreamConfiguration> configs;
> > > -	V4L2SubdeviceFormat format = {};
> > > -
> > > -	/*
> > > -	 * FIXME: As of now, return the image format reported by the sensor.
> > > -	 * In future good defaults should be provided for each stream.
> > > -	 */
> > > -	if (data->sensor_->getFormat(0, &format)) {
> > > -		LOG(IPU3, Error) << "Failed to create stream configurations";
> > > -		return configs;
> > > -	}
> > >
> > >  	StreamConfiguration config = {};
> > > -	config.width = format.width;
> > > -	config.height = format.height;
> > > -	config.pixelFormat = V4L2_PIX_FMT_IPU3_SGRBG10;
> > > +	config.width = 2560;
> > > +	config.height = 1920;
> > > +	config.pixelFormat = V4L2_PIX_FMT_NV12;
> >
> > This is a good change and trust that the format you selected are the
> > correct one so I have not verified it by reading or testing on the IPU3.
> >
> > Reviewed-by: Niklas Söderlund <niklas.soderlund at ragnatech.se>
> >
> > I'm just curious why the pixelformat changes, did something change in
> > the upstream driver or is this in preparation of some later change?
> >
>
> We're preparing to provide frames to the application from the IMGU not from the CIO2 unit. The output format of the two is different.
>
> Thanks
>   j
>
> > >  	config.bufferCount = 4;
> > >
> > >  	configs[&data->stream_] = config;
> > > --
> > > 2.20.1
> > >
> > > _______________________________________________
> > > libcamera-devel mailing list
> > > libcamera-devel at lists.libcamera.org
> > > https://lists.libcamera.org/listinfo/libcamera-devel
> >
> > --
> > Regards,
> > Niklas Söderlund
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