[libcamera-devel] [PATCH v5 05/12] pipeline: raspberrypi: Handle OptionalStream hints for Unicam Image

[Kieran Bingham]

Quoting Naushir Patuck via libcamera-devel (2023-01-18 08:59:46)
> Look for OptionalStream flag in the hints field of the Unicam Image
> StreamConfiguration structure. If this flag is not set, it guarantees that the
> application will provide buffers for Unicam Image, so override the
> minUnicamBuffers and minTotalUnicamBuffers config parameters in the following
> way:
> 
> - If startup drop frames are required, allocate at least 1 internal buffer.
> - If no startup drop frames are required, do not allocate any internal buffers.
> 

As highlighted somewhere else, the only part I hadn't considered when
suggesting this way around is the raw sensor mode configuration. But
that might still be ok.

And probably means we really need a helper or something to improve how
we handle configuring the sensor modes/sizes separately from the output
stream, as here we would have to make sure that configuring a RAW stream
when the application doesn't provide buffers will have to report it's an
OptionalStream in the hint....


> All other buffer allocations remain unchanged.
> 
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> ---
>  .../pipeline/raspberrypi/raspberrypi.cpp      | 36 ++++++++++++++-----
>  1 file changed, 28 insertions(+), 8 deletions(-)
> 
> diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> index 8d325c7a18c5..6ed4cc2c7ba7 100644
> --- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> +++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
> @@ -1448,12 +1448,33 @@ int PipelineHandlerRPi::queueAllBuffers(Camera *camera)
>  int PipelineHandlerRPi::prepareBuffers(Camera *camera)
>  {
>         RPiCameraData *data = cameraData(camera);
> -       unsigned int numRawBuffers = 0;
> +       unsigned int minUnicamBuffers = data->config_.minUnicamBuffers,
> +                    minTotalUnicamBuffers = data->config_.minTotalUnicamBuffers,
> +                    numRawBuffers = 0;
>         int ret;
>  
>         for (Stream *s : camera->streams()) {
> -               if (isRaw(s->configuration().pixelFormat)) {
> +               if (s == &data->unicam_[Unicam::Image]) {
>                         numRawBuffers = s->configuration().bufferCount;
> +                       /*
> +                        * If the application provides a guarantees that Unicam
> +                        * image buffers will always be provided for the RAW stream
> +                        * in a Request, we need:
> +                        * - at least 1 internal Unicam buffer to handle startup frame drops,
> +                        * - no internal Unicam buffers if there are no startup frame drops.
> +                        */
> +                       if (!(s->configuration().hints &
> +                             StreamConfiguration::Hint::OptionalStream)) {
> +                               if (data->dropFrameCount_) {
> +                                       minUnicamBuffers = std::max(1u, minUnicamBuffers);
> +                                       minTotalUnicamBuffers =
> +                                               std::max(minUnicamBuffers, minTotalUnicamBuffers);
> +                               } else {
> +                                       minUnicamBuffers = 0;
> +                                       minTotalUnicamBuffers = 0;
> +                               }
> +                       }
> +
>                         break;
>                 }
>         }
> @@ -1465,7 +1486,6 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
>                  * For Unicam, allocate a minimum number of buffers for internal
>                  * use as we want to avoid any frame drops.
>                  */
> -               const unsigned int minBuffers = data->config_.minTotalUnicamBuffers;
>                 if (stream == &data->unicam_[Unicam::Image]) {
>                         /*
>                          * If an application has configured a RAW stream, allocate
> @@ -1473,8 +1493,8 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
>                          * we have at least minUnicamBuffers of internal buffers
>                          * to use to minimise frame drops.
>                          */
> -                       numBuffers = std::max<int>(data->config_.minUnicamBuffers,
> -                                                  minBuffers - numRawBuffers);
> +                       numBuffers = std::max<int>(minUnicamBuffers,
> +                                                  minTotalUnicamBuffers - numRawBuffers);
>                 } else if (stream == &data->isp_[Isp::Input]) {
>                         /*
>                          * ISP input buffers are imported from Unicam, so follow
> @@ -1482,15 +1502,15 @@ int PipelineHandlerRPi::prepareBuffers(Camera *camera)
>                          * available.
>                          */
>                         numBuffers = numRawBuffers +
> -                                    std::max<int>(data->config_.minUnicamBuffers,
> -                                                  minBuffers - numRawBuffers);
> +                                    std::max<int>(minUnicamBuffers,
> +                                                  minTotalUnicamBuffers - numRawBuffers);
>  
>                 } else if (stream == &data->unicam_[Unicam::Embedded]) {
>                         /*
>                          * Embedded data buffers are (currently) for internal use,
>                          * so allocate the minimum required to avoid frame drops.
>                          */
> -                       numBuffers = minBuffers;
> +                       numBuffers = data->config_.minTotalUnicamBuffers;
>                 } else {
>                         /*
>                          * Since the ISP runs synchronous with the IPA and requests,
> -- 
> 2.25.1
>