[libcamera-devel] [PATCH v2 02/10] pipeline: raspberrypi: Add a pipeline config structure

[Naushir Patuck]

Hi Laurent,

Thanks for the feedback!


On Fri, 2 Dec 2022 at 11:42, Laurent Pinchart <
laurent.pinchart at ideasonboard.com> wrote:

> Hi Naush,
>
> Thank you for the patch.
>
> On Tue, Nov 29, 2022 at 01:45:26PM +0000, Naushir Patuck via
> libcamera-devel wrote:
> > Add a configuration structure to store platform specific parameters used
> by
> > the pipeline handler. Currently, these only store Unicam buffer counts,
> > replacing the hardcoded static values in the source code.
>
> One question here, does the configuration apply to the pipeline, or to
> the camera ? If multiple sensors are connected to the same Unicam
> instance (through an external multiplexers), will all these cameras
> always have the same configuration, or are there use cases for
> per-camera configuration ? Looking at the series, the configuration is
> stored per-camera, but is the same for all cameras handled by the
> pipeline handler.
>

The intention is to allow us to run alternate configurations per-camera.
With this series, raspberrypi/default.json is loaded, unless the env
variable
LIBCAMERA_RPI_CONFIG_FILE is set for the process.  Admittedly this
is not the neatest way of doing things.  We did alway talk about a mechanism
for the application to set the IPA tuning file via some API.  Whatever that
API
may be, I expect the pipeline handler config to follow a similar mechanism.


>
> The answer to that question matters for the implementation in the
> Raspberry Pi pipeline handler, but also in the common helpers in case
> other platforms would need per-camera configurations.
>

Without any sort of override mechanism, this is indeed a problem.


>
> > In subsequent commits, more parameters will be added to the configuration
> > structure, and parameters will be read in through a config file.
> >
> > Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> > Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
> > ---
> >  .../pipeline/raspberrypi/raspberrypi.cpp      | 51 ++++++++++++++++---
> >  1 file changed, 44 insertions(+), 7 deletions(-)
> >
> > diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > index 0e0b71945640..4486d31ea78d 100644
> > --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> > @@ -294,6 +294,21 @@ public:
> >       /* Have internal buffers been allocated? */
> >       bool buffersAllocated_;
> >
> > +     struct Config {
> > +             /*
> > +              * The minimum number of internal buffers to be allocated
> for
> > +              * the Unicam Image stream.
> > +              */
> > +             unsigned int minUnicamBuffers;
> > +             /*
> > +              * The minimum total (internal + external) buffer count
> used for
> > +              * the Unicam Image steram.
>
> s/steram/stream/
>
> > +              */
> > +             unsigned int minTotalUnicamBuffers;
> > +     };
> > +
> > +     Config config_;
> > +
> >  private:
> >       void checkRequestCompleted();
> >       void fillRequestMetadata(const ControlList &bufferControls,
> > @@ -346,6 +361,7 @@ private:
> >       }
> >
> >       int registerCamera(MediaDevice *unicam, MediaDevice *isp,
> MediaEntity *sensorEntity);
> > +     int configurePipelineHandler(RPiCameraData *data);
>
> Wouldn't this be better placed in the RPiCameraData class ? I would also
> name the function loadPipelineHandlerConfiguration() (or similar) to
> make its purpose clearer.
>

Ack


>
> I wonder if we shouldn't instead talk about "pipeline configuration"
> instead of "pipeline handler configuration", especially if the
> configuration is specific to a camera. What does everybody think ?
>

Yes, I agree with that.  Pipeline configuration does sound more appropriate.

Regards,
Naush



> >       int queueAllBuffers(Camera *camera);
> >       int prepareBuffers(Camera *camera);
> >       void mapBuffers(Camera *camera, const RPi::BufferMap &buffers,
> unsigned int mask);
> > @@ -1377,6 +1393,12 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> >       streams.insert(&data->isp_[Isp::Output0]);
> >       streams.insert(&data->isp_[Isp::Output1]);
> >
> > +     int ret = configurePipelineHandler(data.get());
> > +     if (ret) {
> > +             LOG(RPI, Error) << "Unable to configure the pipeline
> handler!";
>
> "Unable to load pipeline handler configuration"
>
> > +             return ret;
> > +     }
> > +
> >       /* Create and register the camera. */
> >       const std::string &id = data->sensor_->id();
> >       std::shared_ptr<Camera> camera =
> > @@ -1389,6 +1411,18 @@ int
> PipelineHandlerRPi::registerCamera(MediaDevice *unicam, MediaDevice *isp, Me
> >       return 0;
> >  }
> >
> > +int PipelineHandlerRPi::configurePipelineHandler(RPiCameraData *data)
> > +{
> > +     RPiCameraData::Config &config = data->config_;
> > +
> > +     config = {
> > +             .minUnicamBuffers = 2,
> > +             .minTotalUnicamBuffers = 4,
> > +     };
> > +
> > +     return 0;
> > +}
> > +
> >  int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
> >  {
> >       RPiCameraData *data = cameraData(camera);
> > @@ -1439,25 +1473,28 @@ int PipelineHandlerRPi::prepareBuffers(Camera
> *camera)
> >       for (auto const stream : data->streams_) {
> >               unsigned int numBuffers;
> >               /*
> > -              * For Unicam, allocate a minimum of 4 buffers as we want
> > -              * to avoid any frame drops.
> > +              * For Unicam, allocate a minimum number of buffers for
> internal
> > +              * use as we want to avoid any frame drops.
> >                */
> > -             constexpr unsigned int minBuffers = 4;
> > +             const unsigned int minBuffers =
> data->config_.minTotalUnicamBuffers;
> >               if (stream == &data->unicam_[Unicam::Image]) {
> >                       /*
> >                        * If an application has configured a RAW stream,
> allocate
> >                        * additional buffers to make up the minimum, but
> ensure
> > -                      * we have at least 2 sets of internal buffers to
> use to
> > -                      * minimise frame drops.
> > +                      * we have at least minUnicamBuffers sets of
> internal
>
> I'd drop 'sets' here as it's not two buffer sets but two buffers.
>
> > +                      * buffers to use to minimise frame drops.
> >                        */
> > -                     numBuffers = std::max<int>(2, minBuffers -
> numRawBuffers);
> > +                     numBuffers =
> std::max<int>(data->config_.minUnicamBuffers,
> > +                                                minBuffers -
> numRawBuffers);
> >               } else if (stream == &data->isp_[Isp::Input]) {
> >                       /*
> >                        * ISP input buffers are imported from Unicam, so
> follow
> >                        * similar logic as above to count all the RAW
> buffers
> >                        * available.
> >                        */
> > -                     numBuffers = numRawBuffers + std::max<int>(2,
> minBuffers - numRawBuffers);
> > +                     numBuffers = numRawBuffers +
> > +
> std::max<int>(data->config_.minUnicamBuffers,
> > +                                                minBuffers -
> numRawBuffers);
> >
> >               } else if (stream == &data->unicam_[Unicam::Embedded]) {
> >                       /*
>
> --
> Regards,
>
> Laurent Pinchart
>
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