[libcamera-devel,v2,16/20] ipa: rpi: agc: Add an AGC stable region
diff mbox series

Message ID 20231013074841.16972-17-naush@raspberrypi.com
State Accepted
Headers show
Series
  • Raspberry Pi: Preliminary PiSP support
Related show

Commit Message

Naushir Patuck Oct. 13, 2023, 7:48 a.m. UTC
From: David Plowman <david.plowman@raspberrypi.com>

Add a small "stable region" parameter (defaulting to 2%) within which
the AGC will not adjust the exposure it requests. It allows
applications to configure the AGC to avoid continual micro-adjustments
of exposure values if they are somehow sensitive to it.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
 src/ipa/rpi/controller/rpi/agc_channel.cpp | 7 +++++++
 src/ipa/rpi/controller/rpi/agc_channel.h   | 1 +
 2 files changed, 8 insertions(+)

Patch
diff mbox series

diff --git a/src/ipa/rpi/controller/rpi/agc_channel.cpp b/src/ipa/rpi/controller/rpi/agc_channel.cpp
index 3957dbc3fa32..1e7eae06d425 100644
--- a/src/ipa/rpi/controller/rpi/agc_channel.cpp
+++ b/src/ipa/rpi/controller/rpi/agc_channel.cpp
@@ -251,6 +251,8 @@  int AgcConfig::read(const libcamera::YamlObject &params)
 	defaultExposureTime = params["default_exposure_time"].get<double>(1000) * 1us;
 	defaultAnalogueGain = params["default_analogue_gain"].get<double>(1.0);
 
+	stableRegion = params["stable_region"].get<double>(0.02);
+
 	return 0;
 }
 
@@ -871,6 +873,8 @@  bool AgcChannel::applyDigitalGain(double gain, double targetY, bool channelBound
 void AgcChannel::filterExposure()
 {
 	double speed = config_.speed;
+	double stableRegion = config_.stableRegion;
+
 	/*
 	 * AGC adapts instantly if both shutter and gain are directly specified
 	 * or we're in the startup phase.
@@ -880,6 +884,9 @@  void AgcChannel::filterExposure()
 		speed = 1.0;
 	if (!filtered_.totalExposure) {
 		filtered_.totalExposure = target_.totalExposure;
+	} else if (filtered_.totalExposure * (1.0 - stableRegion) < target_.totalExposure &&
+		   filtered_.totalExposure * (1.0 + stableRegion) > target_.totalExposure) {
+		/* Total exposure must change by more than this or we leave it alone. */
 	} else {
 		/*
 		 * If close to the result go faster, to save making so many
diff --git a/src/ipa/rpi/controller/rpi/agc_channel.h b/src/ipa/rpi/controller/rpi/agc_channel.h
index ae826fa8097f..c1808422498a 100644
--- a/src/ipa/rpi/controller/rpi/agc_channel.h
+++ b/src/ipa/rpi/controller/rpi/agc_channel.h
@@ -75,6 +75,7 @@  struct AgcConfig {
 	double baseEv;
 	libcamera::utils::Duration defaultExposureTime;
 	double defaultAnalogueGain;
+	double stableRegion;
 };
 
 class AgcChannel