[libcamera-devel] [PATCH v1 5/6] pipeline: raspberrypi: Repurpose RPi::Stream::reset()

[David Plowman]

Hi Naush

Thanks for this patch!

On Mon, 7 Mar 2022 at 12:46, Naushir Patuck via libcamera-devel
<libcamera-devel at lists.libcamera.org> wrote:
>
> The original use of RPi::Stream::reset() was to clear the external flag state
> and free/clear out the framebuffers for the stream. However, the latter is now
> done through PipelineHandlerRPi::configure(). Rework
> PipelineHandlerRPi::configure() to call RPi::Stream::setExternal() instead of
> RPi::Stream::reset() to achieve the same thing.
>
> Repurpose RPi::Stream::reset() to instead reset the state of the buffer handling
> logic, where all internally allocated buffers are put back into the queue of
> available buffers. This reset() is now called from PipelineHandlerRPi::start(),
> allowing the pipeline handler to correctly deal with start()/stop()/start()
> sequences and reusing the buffers allocated on the first start().
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  src/libcamera/pipeline/raspberrypi/raspberrypi.cpp |  5 ++++-
>  src/libcamera/pipeline/raspberrypi/rpi_stream.cpp  | 11 +++++------
>  2 files changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> index b17ffa235ac7..193361686d3c 100644
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> @@ -692,7 +692,7 @@ int PipelineHandlerRPi::configure(Camera *camera, CameraConfiguration *config)
>         /* Start by freeing all buffers and resetting the Unicam and ISP stream states. */
>         data->freeBuffers();
>         for (auto const stream : data->streams_)
> -               stream->reset();
> +               stream->setExternal(false);

So I think that replacing the former calls to reset() by setExternal()
is a good thing, because "reset" didn't give you much of a clue about
what was being reset!

I guess my only feeling about repurposing the name "reset" is that
it's still rather vague. Could we think of a name that gives someone a
clue as to what is being reset? Maybe "resetAvailableBuffers", or just
"resetBuffers"?

>
>         BayerFormat::Packing packing = BayerFormat::Packing::CSI2;
>         Size maxSize, sensorSize;
> @@ -985,6 +985,9 @@ int PipelineHandlerRPi::start(Camera *camera, const ControlList *controls)
>         RPiCameraData *data = cameraData(camera);
>         int ret;
>
> +       for (auto const stream : data->streams_)
> +               stream->reset();
> +
>         if (data->reconfigured_) {
>                 /* Allocate buffers for internal pipeline usage. */
>                 ret = prepareBuffers(camera);
> diff --git a/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp b/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
> index f446e1ce66c7..0840ec4f54a0 100644
> --- a/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/rpi_stream.cpp
> @@ -28,8 +28,10 @@ std::string Stream::name() const
>
>  void Stream::reset()
>  {
> -       external_ = false;
> -       clearBuffers();
> +       /* Add all internal buffers to the queue of usable buffers. */
> +       availableBuffers_ = {};
> +       for (auto const &buffer : internalBuffers_)
> +               availableBuffers_.push(buffer.get());
>  }
>
>  void Stream::setExternal(bool external)
> @@ -97,10 +99,7 @@ int Stream::prepareBuffers(unsigned int count)
>
>                         /* Add these exported buffers to the internal/external buffer list. */
>                         setExportedBuffers(&internalBuffers_);
> -
> -                       /* Add these buffers to the queue of internal usable buffers. */
> -                       for (auto const &buffer : internalBuffers_)
> -                               availableBuffers_.push(buffer.get());
> +                       reset();
>                 }
>
>                 /* We must import all internal/external exported buffers. */
> --
> 2.25.1
>

But either way, with or without any further changes:

Reviewed-by: David Plowman <david.plowman at raspberrypi.com>
Tested-by: David Plowman <david.plowman at raspberrypi.com>

Thanks!
David