[v3,5/6] libcamera: software_isp: Add valid flag to struct SwIspStats

24483 diff mbox series

Generating statistics for every single frame is not really necessary.

However a roundtrip through ipa_->processStats() still need to be done
every frame, even if there are no stats to make the IPA generate metadata
for every frame.

Add a valid flag to the statistics struct to let the IPA know when there
are no statistics for the frame being processed and modify the IPA to
only generate metadata for frames without valid statistics.

This is a preparation patch for skipping statistics generation for some
frames.

Signed-off-by: Hans de Goede <hansg@kernel.org>
---
Changes in v3:
- Drop if (!stats_->valid) early exit from IPASoftSimple::processStats()
- Save last AGC calculated new gain and exposure values and re-use these
  for frames without statistics, this avoids delayedCtrl history underruns
- Improve SwIspStats.valid documentation

Changes in v2:
- This is a new patch in v2 of this series
---
 .../libcamera/internal/software_isp/swisp_stats.h   |  5 +++++
 src/ipa/simple/algorithms/agc.cpp                   | 13 +++++++++++++
 src/ipa/simple/algorithms/awb.cpp                   |  3 +++
 src/ipa/simple/algorithms/blc.cpp                   |  3 +++
 src/ipa/simple/ipa_context.h                        |  4 ++++
 src/libcamera/software_isp/debayer_cpu.cpp          |  2 +-
 src/libcamera/software_isp/swstats_cpu.cpp          |  4 +++-
 src/libcamera/software_isp/swstats_cpu.h            |  2 +-
 8 files changed, 33 insertions(+), 3 deletions(-)

Quoting Hans de Goede (2025-09-27 19:00:03)
> Generating statistics for every single frame is not really necessary.
> 
> However a roundtrip through ipa_->processStats() still need to be done
> every frame, even if there are no stats to make the IPA generate metadata
> for every frame.
> 
> Add a valid flag to the statistics struct to let the IPA know when there
> are no statistics for the frame being processed and modify the IPA to
> only generate metadata for frames without valid statistics.
> 
> This is a preparation patch for skipping statistics generation for some
> frames.
> 
> Signed-off-by: Hans de Goede <hansg@kernel.org>

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

> ---
> Changes in v3:
> - Drop if (!stats_->valid) early exit from IPASoftSimple::processStats()
> - Save last AGC calculated new gain and exposure values and re-use these
>   for frames without statistics, this avoids delayedCtrl history underruns
> - Improve SwIspStats.valid documentation
> 
> Changes in v2:
> - This is a new patch in v2 of this series
> ---
>  .../libcamera/internal/software_isp/swisp_stats.h   |  5 +++++
>  src/ipa/simple/algorithms/agc.cpp                   | 13 +++++++++++++
>  src/ipa/simple/algorithms/awb.cpp                   |  3 +++
>  src/ipa/simple/algorithms/blc.cpp                   |  3 +++
>  src/ipa/simple/ipa_context.h                        |  4 ++++
>  src/libcamera/software_isp/debayer_cpu.cpp          |  2 +-
>  src/libcamera/software_isp/swstats_cpu.cpp          |  4 +++-
>  src/libcamera/software_isp/swstats_cpu.h            |  2 +-
>  8 files changed, 33 insertions(+), 3 deletions(-)
> 
> diff --git a/include/libcamera/internal/software_isp/swisp_stats.h b/include/libcamera/internal/software_isp/swisp_stats.h
> index ae11f112..3c986018 100644
> --- a/include/libcamera/internal/software_isp/swisp_stats.h
> +++ b/include/libcamera/internal/software_isp/swisp_stats.h
> @@ -20,6 +20,11 @@ namespace libcamera {
>   * wrap around.
>   */
>  struct SwIspStats {
> +       /**
> +        * \brief True if the statistics buffer contains valid data, false if
> +        *        no statistics were generated for this frame
> +        */
> +       bool valid;
>         /**
>          * \brief Holds the sum of all sampled red pixels
>          */
> diff --git a/src/ipa/simple/algorithms/agc.cpp b/src/ipa/simple/algorithms/agc.cpp
> index 3471cc88..af660a03 100644
> --- a/src/ipa/simple/algorithms/agc.cpp
> +++ b/src/ipa/simple/algorithms/agc.cpp
> @@ -91,6 +91,9 @@ void Agc::updateExposure(IPAContext &context, IPAFrameContext &frameContext, dou
>         again = std::clamp(again, context.configuration.agc.againMin,
>                            context.configuration.agc.againMax);
>  
> +       context.activeState.agc.exposure = exposure;
> +       context.activeState.agc.again = again;
> +
>         LOG(IPASoftExposure, Debug)
>                 << "exposureMSV " << exposureMSV
>                 << " exp " << exposure << " again " << again;
> @@ -107,6 +110,16 @@ void Agc::process(IPAContext &context,
>         metadata.set(controls::ExposureTime, exposureTime.get<std::micro>());
>         metadata.set(controls::AnalogueGain, frameContext.sensor.gain);
>  
> +       if (!stats->valid) {
> +               /*
> +                * Use the new exposure and gain values calculated the last time
> +                * there were valid stats.
> +                */
> +               frameContext.sensor.exposure = context.activeState.agc.exposure;
> +               frameContext.sensor.gain = context.activeState.agc.again;
> +               return;
> +       }
> +
>         /*
>          * Calculate Mean Sample Value (MSV) according to formula from:
>          * https://www.araa.asn.au/acra/acra2007/papers/paper84final.pdf
> diff --git a/src/ipa/simple/algorithms/awb.cpp b/src/ipa/simple/algorithms/awb.cpp
> index cf567e89..ddd0b791 100644
> --- a/src/ipa/simple/algorithms/awb.cpp
> +++ b/src/ipa/simple/algorithms/awb.cpp
> @@ -61,6 +61,9 @@ void Awb::process(IPAContext &context,
>         };
>         metadata.set(controls::ColourGains, mdGains);
>  
> +       if (!stats->valid)
> +               return;
> +
>         /*
>          * Black level must be subtracted to get the correct AWB ratios, they
>          * would be off if they were computed from the whole brightness range
> diff --git a/src/ipa/simple/algorithms/blc.cpp b/src/ipa/simple/algorithms/blc.cpp
> index 8c1e9ed0..616da0ee 100644
> --- a/src/ipa/simple/algorithms/blc.cpp
> +++ b/src/ipa/simple/algorithms/blc.cpp
> @@ -60,6 +60,9 @@ void BlackLevel::process(IPAContext &context,
>         };
>         metadata.set(controls::SensorBlackLevels, blackLevels);
>  
> +       if (!stats->valid)
> +               return;
> +
>         if (context.configuration.black.level.has_value())
>                 return;
>  
> diff --git a/src/ipa/simple/ipa_context.h b/src/ipa/simple/ipa_context.h
> index 468fccab..441f2a73 100644
> --- a/src/ipa/simple/ipa_context.h
> +++ b/src/ipa/simple/ipa_context.h
> @@ -37,6 +37,10 @@ struct IPASessionConfiguration {
>  };
>  
>  struct IPAActiveState {
> +       struct {
> +               int32_t exposure;
> +               double again;
> +       } agc;
>         struct {
>                 uint8_t level;
>                 int32_t lastExposure;
> diff --git a/src/libcamera/software_isp/debayer_cpu.cpp b/src/libcamera/software_isp/debayer_cpu.cpp
> index 2dc85e5e..bfa60888 100644
> --- a/src/libcamera/software_isp/debayer_cpu.cpp
> +++ b/src/libcamera/software_isp/debayer_cpu.cpp
> @@ -851,7 +851,7 @@ void DebayerCpu::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output
>          *
>          * \todo Pass real bufferId once stats buffer passing is changed.
>          */
> -       stats_->finishFrame(frame, 0);
> +       stats_->finishFrame(frame, 0, true);
>         outputBufferReady.emit(output);
>         inputBufferReady.emit(input);
>  }
> diff --git a/src/libcamera/software_isp/swstats_cpu.cpp b/src/libcamera/software_isp/swstats_cpu.cpp
> index 4b77b360..da91f912 100644
> --- a/src/libcamera/software_isp/swstats_cpu.cpp
> +++ b/src/libcamera/software_isp/swstats_cpu.cpp
> @@ -313,11 +313,13 @@ void SwStatsCpu::startFrame(void)
>   * \brief Finish statistics calculation for the current frame
>   * \param[in] frame The frame number
>   * \param[in] bufferId ID of the statistics buffer
> + * \param[in] valid Indicates if the statistics for the current frame are valid
>   *
>   * This may only be called after a successful setWindow() call.
>   */
> -void SwStatsCpu::finishFrame(uint32_t frame, uint32_t bufferId)
> +void SwStatsCpu::finishFrame(uint32_t frame, uint32_t bufferId, bool valid)
>  {
> +       stats_.valid = valid;
>         *sharedStats_ = stats_;
>         statsReady.emit(frame, bufferId);
>  }
> diff --git a/src/libcamera/software_isp/swstats_cpu.h b/src/libcamera/software_isp/swstats_cpu.h
> index 26a2f462..6ac3c4de 100644
> --- a/src/libcamera/software_isp/swstats_cpu.h
> +++ b/src/libcamera/software_isp/swstats_cpu.h
> @@ -41,7 +41,7 @@ public:
>         int configure(const StreamConfiguration &inputCfg);
>         void setWindow(const Rectangle &window);
>         void startFrame();
> -       void finishFrame(uint32_t frame, uint32_t bufferId);
> +       void finishFrame(uint32_t frame, uint32_t bufferId, bool valid);
>  
>         void processLine0(unsigned int y, const uint8_t *src[])
>         {
> -- 
> 2.51.0
>