ipa: rkisp1: agc: Add a histogram-based gain

As for the IPU3, we can estimate the histogram of the luminance. The
RkISP1 can estimate multiple ones, the R, G and B ones, the Y only one
and a combination of RGB. The one we are interested by in AGC is the Y
histogram.

Use the hardware revision to determine the number of bins of the
produced histogram.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Tested-by: Peter Griffin <peter.griffin@linaro.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/src/ipa/rkisp1/algorithms/agc.h b/src/ipa/rkisp1/algorithms/agc.h
index 942c9d7a..ce1adf27 100644
--- a/src/ipa/rkisp1/algorithms/agc.h
+++ b/src/ipa/rkisp1/algorithms/agc.h
@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 /*
- * Copyright (C) 2021, Ideas On Board
+ * Copyright (C) 2021-2022, Ideas On Board
  *
  * agc.h - RkISP1 AGC/AEC mean-based control algorithm
  */
@@ -32,13 +32,15 @@ public:
 	void process(IPAContext &context, const rkisp1_stat_buffer *stats) override;
 
 private:
-	void computeExposure(IPAContext &Context, double yGain);
+	void computeExposure(IPAContext &Context, double yGain, double iqMeanGain);
 	utils::Duration filterExposure(utils::Duration exposureValue);
 	double estimateLuminance(const rkisp1_cif_isp_ae_stat *ae, double gain);
+	double measureBrightness(const rkisp1_cif_isp_hist_stat *hist) const;
 
 	uint64_t frameCount_;
 
 	uint32_t numCells_;
+	uint32_t numHistBins_;
 
 	utils::Duration filteredExposure_;
 };