From 03bae6b9248280a3edd9350061cc307d95ba1cd0 Mon Sep 17 00:00:00 2001 From: Stefan Klug Date: Wed, 26 Mar 2025 14:47:21 +0100 Subject: ipa: libipa: agc_mean_luminance: Error out when effectiveExposureValue is zero In a proper system it never happens that the effectiveExposureValue drops to zero. If that still happens due to a bug outside of agc_mean_luminance, the calculated gain goes towards infinity but the newExposureValue is still 0 because it is the result of multiplying the effectiveExposureTime with the gain, leading to wild oscillations. Catch that condition, print an error message and set the new effective exposure value to an arbitrary 10ms. Note that in any case the underlying problem must be fixed. The important change is the added error message to be able to detect such a situation. Signed-off-by: Stefan Klug Reviewed-by: Daniel Scally Reviewed-by: Laurent Pinchart --- src/ipa/libipa/agc_mean_luminance.cpp | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/src/ipa/libipa/agc_mean_luminance.cpp b/src/ipa/libipa/agc_mean_luminance.cpp index 02555a44..f617fde8 100644 --- a/src/ipa/libipa/agc_mean_luminance.cpp +++ b/src/ipa/libipa/agc_mean_luminance.cpp @@ -541,6 +541,18 @@ AgcMeanLuminance::calculateNewEv(uint32_t constraintModeIndex, std::shared_ptr exposureModeHelper = exposureModeHelpers_.at(exposureModeIndex); + if (effectiveExposureValue == 0s) { + LOG(AgcMeanLuminance, Error) + << "Effective exposure value is 0. This is a bug in AGC " + "and must be fixed for proper operation."; + /* + * Return an arbitrary exposure time > 0 to ensure regulation + * doesn't get stuck with 0 in case the sensor driver allows a + * min exposure of 0. + */ + return exposureModeHelper->splitExposure(10ms); + } + double gain = estimateInitialGain(); gain = constraintClampGain(constraintModeIndex, yHist, gain); -- cgit v1.2.1