[v2,4/6] ipa: software_isp: AGC: Only use integers for exposure calculations
diff mbox series

Message ID 20250925221708.7471-5-hansg@kernel.org
State New
Headers show
Series
  • ipa: software_isp: AGC: Fox AGC oscillation bug
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Commit Message

Hans de Goede Sept. 25, 2025, 10:17 p.m. UTC 
Exposure is an integer, instead of re-using the "double next" used
for again calculations, doing intermediate calculations with double
precision, use a local next variable of an integer type.

Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.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>
---
 src/ipa/simple/algorithms/agc.cpp | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

Patch
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diff --git a/src/ipa/simple/algorithms/agc.cpp b/src/ipa/simple/algorithms/agc.cpp
index f7f73451..3471cc88 100644
--- a/src/ipa/simple/algorithms/agc.cpp
+++ b/src/ipa/simple/algorithms/agc.cpp
@@ -51,19 +51,18 @@  void Agc::updateExposure(IPAContext &context, IPAFrameContext &frameContext, dou
 	static constexpr uint8_t kExpNumeratorUp = kExpDenominator + 1;
 	static constexpr uint8_t kExpNumeratorDown = kExpDenominator - 1;
 
-	double next;
 	int32_t &exposure = frameContext.sensor.exposure;
 	double &again = frameContext.sensor.gain;
 
 	if (exposureMSV < kExposureOptimal - kExposureSatisfactory) {
 		if (exposure < context.configuration.agc.exposureMax) {
-			next = exposure * kExpNumeratorUp / kExpDenominator;
+			int32_t next = exposure * kExpNumeratorUp / kExpDenominator;
 			if (next - exposure < 1)
 				exposure += 1;
 			else
 				exposure = next;
 		} else {
-			next = again * kExpNumeratorUp / kExpDenominator;
+			double next = again * kExpNumeratorUp / kExpDenominator;
 			if (next - again < context.configuration.agc.againMinStep)
 				again += context.configuration.agc.againMinStep;
 			else
@@ -73,13 +72,13 @@  void Agc::updateExposure(IPAContext &context, IPAFrameContext &frameContext, dou
 
 	if (exposureMSV > kExposureOptimal + kExposureSatisfactory) {
 		if (again > context.configuration.agc.again10) {
-			next = again * kExpNumeratorDown / kExpDenominator;
+			double next = again * kExpNumeratorDown / kExpDenominator;
 			if (again - next < context.configuration.agc.againMinStep)
 				again -= context.configuration.agc.againMinStep;
 			else
 				again = next;
 		} else {
-			next = exposure * kExpNumeratorDown / kExpDenominator;
+			int32_t next = exposure * kExpNumeratorDown / kExpDenominator;
 			if (exposure - next < 1)
 				exposure -= 1;
 			else