[libcamera-devel] [PATCH 2/4] ipa: ipu3: Calculate line duration from IPACameraSensorInfo

[Laurent Pinchart]

Hi Umang,

Thank you for the patch.

On Wed, Jun 02, 2021 at 03:53:24PM +0530, Umang Jain wrote:
> Squash \todo by calculating line duration from IPACameraSensorInfo,
> now passed in, to IPU3Agc::initialise().
> 
> Since line duration is now calculated from real values, store it as a
> private member in IPU3Agc class. As a further step, replace the
> associated global constant, kMaxExposureTime, with a private IPU3Agc
> class member as well, and assign its value correspondingly in
> IPU3Agc::initialise(), similar to previous precedence.
> 
> Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
> ---
>  src/ipa/ipu3/ipu3.cpp     |  2 +-
>  src/ipa/ipu3/ipu3_agc.cpp | 22 +++++++++++-----------
>  src/ipa/ipu3/ipu3_agc.h   |  7 ++++++-
>  3 files changed, 18 insertions(+), 13 deletions(-)
> 
> diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
> index 700a5660..2496b0a0 100644
> --- a/src/ipa/ipu3/ipu3.cpp
> +++ b/src/ipa/ipu3/ipu3.cpp
> @@ -174,7 +174,7 @@ void IPAIPU3::configure(const IPAConfigInfo &configInfo)
>  	awbAlgo_->initialise(params_, configInfo.bdsOutputSize, bdsGrid_);
>  
>  	agcAlgo_ = std::make_unique<IPU3Agc>();
> -	agcAlgo_->initialise(bdsGrid_);
> +	agcAlgo_->initialise(bdsGrid_, configInfo.sensorInfo);
>  }
>  
>  void IPAIPU3::mapBuffers(const std::vector<IPABuffer> &buffers)
> diff --git a/src/ipa/ipu3/ipu3_agc.cpp b/src/ipa/ipu3/ipu3_agc.cpp
> index 8bae423f..ccd01371 100644
> --- a/src/ipa/ipu3/ipu3_agc.cpp
> +++ b/src/ipa/ipu3/ipu3_agc.cpp
> @@ -39,11 +39,6 @@ static constexpr uint32_t kMaxGain = kMaxISO / 100;
>  static constexpr uint32_t kMinExposure = 1;
>  static constexpr uint32_t kMaxExposure = 1976;
>  
> -/* \todo those should be got from IPACameraSensorInfo ! */
> -/* line duration in microseconds */
> -static constexpr double kLineDuration = 16.8;
> -static constexpr double kMaxExposureTime = kMaxExposure * kLineDuration;
> -
>  /* Histogram constants */
>  static constexpr uint32_t knumHistogramBins = 256;
>  static constexpr double kEvGainTarget = 0.5;
> @@ -54,14 +49,19 @@ static constexpr uint8_t kCellSize = 8;
>  IPU3Agc::IPU3Agc()
>  	: frameCount_(0), lastFrame_(0), converged_(false),
>  	  updateControls_(false), iqMean_(0.0), gamma_(1.0),
> +	  lineDuration_(0.0), maxExposureTime_(0.0),
>  	  prevExposure_(0.0), prevExposureNoDg_(0.0),
>  	  currentExposure_(0.0), currentExposureNoDg_(0.0)
>  {
>  }
>  
> -void IPU3Agc::initialise(struct ipu3_uapi_grid_config &bdsGrid)
> +void IPU3Agc::initialise(struct ipu3_uapi_grid_config &bdsGrid, const IPACameraSensorInfo &sensorInfo)
>  {
>  	aeGrid_ = bdsGrid;
> +
> +	/* line duration in microseconds */
> +	lineDuration_ = sensorInfo.lineLength / static_cast<double>(sensorInfo.pixelRate / 1000000);

Let's try to avoid losing precision.

	lineDuration_ = sensorInfo.lineLength * 1000000ULL
		      / static_cast<double>(sensorInfo.pixelRate);

On a side note, we should really move to std::chrono types at some
point.

> +	maxExposureTime_ = kMaxExposure * lineDuration_;
>  }
>  
>  void IPU3Agc::processBrightness(const ipu3_uapi_stats_3a *stats)
> @@ -160,13 +160,13 @@ void IPU3Agc::lockExposureGain(uint32_t &exposure, uint32_t &gain)
>  		double newGain = kEvGainTarget * knumHistogramBins / iqMean_;
>  
>  		/* extracted from Rpi::Agc::computeTargetExposure */
> -		double currentShutter = exposure * kLineDuration;
> +		double currentShutter = exposure * lineDuration_;
>  		currentExposureNoDg_ = currentShutter * gain;
>  		LOG(IPU3Agc, Debug) << "Actual total exposure " << currentExposureNoDg_
>  				    << " Shutter speed " << currentShutter
>  				    << " Gain " << gain;
>  		currentExposure_ = currentExposureNoDg_ * newGain;
> -		double maxTotalExposure = kMaxExposureTime * kMaxGain;
> +		double maxTotalExposure = maxExposureTime_ * kMaxGain;
>  		currentExposure_ = std::min(currentExposure_, maxTotalExposure);
>  		LOG(IPU3Agc, Debug) << "Target total exposure " << currentExposure_;
>  
> @@ -174,18 +174,18 @@ void IPU3Agc::lockExposureGain(uint32_t &exposure, uint32_t &gain)
>  		filterExposure();
>  
>  		double newExposure = 0.0;
> -		if (currentShutter < kMaxExposureTime) {
> +		if (currentShutter < maxExposureTime_) {
>  			exposure = std::clamp(static_cast<uint32_t>(exposure * currentExposure_ / currentExposureNoDg_), kMinExposure, kMaxExposure);
>  			newExposure = currentExposure_ / exposure;
>  			gain = std::clamp(static_cast<uint32_t>(gain * currentExposure_ / newExposure), kMinGain, kMaxGain);
>  			updateControls_ = true;
> -		} else if (currentShutter >= kMaxExposureTime) {
> +		} else if (currentShutter >= maxExposureTime_) {
>  			gain = std::clamp(static_cast<uint32_t>(gain * currentExposure_ / currentExposureNoDg_), kMinGain, kMaxGain);
>  			newExposure = currentExposure_ / gain;
>  			exposure = std::clamp(static_cast<uint32_t>(exposure * currentExposure_ / newExposure), kMinExposure, kMaxExposure);
>  			updateControls_ = true;
>  		}
> -		LOG(IPU3Agc, Debug) << "Adjust exposure " << exposure * kLineDuration << " and gain " << gain;
> +		LOG(IPU3Agc, Debug) << "Adjust exposure " << exposure * lineDuration_ << " and gain " << gain;
>  	}
>  	lastFrame_ = frameCount_;
>  }
> diff --git a/src/ipa/ipu3/ipu3_agc.h b/src/ipa/ipu3/ipu3_agc.h
> index bfdf45d1..ae557bdd 100644
> --- a/src/ipa/ipu3/ipu3_agc.h
> +++ b/src/ipa/ipu3/ipu3_agc.h
> @@ -12,6 +12,8 @@
>  
>  #include <linux/intel-ipu3.h>
>  
> +#include <libcamera/ipa/ipu3_ipa_interface.h>
> +

No need for a blank line, and you can swap the two headers to order them
alphabetically. As Kieran mentioned, you can include
core_ipa_interface.h instead, or, possibly better, forward-declare the
IPACameraSensorInfo struct and include core_ipa_interface.h in
ipu3_agc.cpp.

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

>  #include <libcamera/geometry.h>
>  
>  #include "libipa/algorithm.h"
> @@ -26,7 +28,7 @@ public:
>  	IPU3Agc();
>  	~IPU3Agc() = default;
>  
> -	void initialise(struct ipu3_uapi_grid_config &bdsGrid);
> +	void initialise(struct ipu3_uapi_grid_config &bdsGrid, const IPACameraSensorInfo &sensorInfo);
>  	void process(const ipu3_uapi_stats_3a *stats, uint32_t &exposure, uint32_t &gain);
>  	bool converged() { return converged_; }
>  	bool updateControls() { return updateControls_; }
> @@ -49,6 +51,9 @@ private:
>  	double iqMean_;
>  	double gamma_;
>  
> +	double lineDuration_;
> +	double maxExposureTime_;
> +
>  	double prevExposure_;
>  	double prevExposureNoDg_;
>  	double currentExposure_;

-- 
Regards,

Laurent Pinchart