[v4,5/6] libcamera: software_isp: Add valid flag to struct SwIspStats
diff mbox series

Message ID 20250930150428.11101-6-hansg@kernel.org
State New
Headers show
Series
  • ipa: software_isp: AGC: Fix AGC oscillation bug
Related show

Commit Message

Hans de Goede Sept. 30, 2025, 3:04 p.m. UTC 
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.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Tested-by: Milan Zamazal <mzamazal@redhat.com>
Tested-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Hans de Goede <hansg@kernel.org>
---
Changes in v4:
- Add an empty line after the agc substruct declaration
- Init active-state agc gain and exposue from sensor values in case
  updateExposure() does not run for the first frame

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
---
 .../internal/software_isp/swisp_stats.h       |  5 ++++
 src/ipa/simple/algorithms/agc.cpp             | 24 ++++++++++++++++++-
 src/ipa/simple/algorithms/awb.cpp             |  3 +++
 src/ipa/simple/algorithms/blc.cpp             |  3 +++
 src/ipa/simple/ipa_context.h                  |  5 ++++
 src/libcamera/software_isp/swstats_cpu.cpp    |  1 +
 6 files changed, 40 insertions(+), 1 deletion(-)

Patch
diff mbox series 

diff --git a/include/libcamera/internal/software_isp/swisp_stats.h b/include/libcamera/internal/software_isp/swisp_stats.h
index ae11f112e..3c9860185 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 3471cc881..e0447cbd6 100644
--- a/src/ipa/simple/algorithms/agc.cpp
+++ b/src/ipa/simple/algorithms/agc.cpp
@@ -91,13 +91,16 @@  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;
 }
 
 void Agc::process(IPAContext &context,
-		  [[maybe_unused]] const uint32_t frame,
+		  const uint32_t frame,
 		  IPAFrameContext &frameContext,
 		  const SwIspStats *stats,
 		  ControlList &metadata)
@@ -107,6 +110,25 @@  void Agc::process(IPAContext &context,
 	metadata.set(controls::ExposureTime, exposureTime.get<std::micro>());
 	metadata.set(controls::AnalogueGain, frameContext.sensor.gain);
 
+	if (frame == 0) {
+		/*
+		 * Init active-state from sensor values in case updateExposure()
+		 * does not run for the first frame.
+		 */
+		context.activeState.agc.exposure = frameContext.sensor.exposure;
+		context.activeState.agc.again = 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 cf567e894..ddd0b7914 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 8c1e9ed08..616da0ee7 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 468fccabb..c3081e306 100644
--- a/src/ipa/simple/ipa_context.h
+++ b/src/ipa/simple/ipa_context.h
@@ -37,6 +37,11 @@  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/swstats_cpu.cpp b/src/libcamera/software_isp/swstats_cpu.cpp
index 4b77b3600..eb416dfdc 100644
--- a/src/libcamera/software_isp/swstats_cpu.cpp
+++ b/src/libcamera/software_isp/swstats_cpu.cpp
@@ -318,6 +318,7 @@  void SwStatsCpu::startFrame(void)
  */
 void SwStatsCpu::finishFrame(uint32_t frame, uint32_t bufferId)
 {
+	stats_.valid = true;
 	*sharedStats_ = stats_;
 	statsReady.emit(frame, bufferId);
 }