[PATCH v1 1/5] ipa: rkisp1: awb: Clamp gains to machine limits

[Stefan Klug]

When the color gains where set manually it was possible to specify a
gain that wrapped the hardware limits. It would also be possible to
further tune the floating point limits, but that is an error prone
approach. So the limits are imposed on the integers, just before writing
to the hardware. This noticeably reduces some oscillations in the awb
regulation.

Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
---
 src/ipa/rkisp1/algorithms/awb.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
index a01fe5d90973..1a5d4776970a 100644
--- a/src/ipa/rkisp1/algorithms/awb.cpp
+++ b/src/ipa/rkisp1/algorithms/awb.cpp
@@ -120,10 +120,14 @@ void Awb::prepare(IPAContext &context, const uint32_t frame,
 		frameContext.awb.gains.blue = context.activeState.awb.gains.automatic.blue;
 	}
 
-	params->others.awb_gain_config.gain_green_b = 256 * frameContext.awb.gains.green;
-	params->others.awb_gain_config.gain_blue = 256 * frameContext.awb.gains.blue;
-	params->others.awb_gain_config.gain_red = 256 * frameContext.awb.gains.red;
-	params->others.awb_gain_config.gain_green_r = 256 * frameContext.awb.gains.green;
+	params->others.awb_gain_config.gain_green_b =
+		std::clamp<int>(256 * frameContext.awb.gains.green, 0, 0x3ff);
+	params->others.awb_gain_config.gain_blue =
+		std::clamp<int>(256 * frameContext.awb.gains.blue, 0, 0x3ff);
+	params->others.awb_gain_config.gain_red =
+		std::clamp<int>(256 * frameContext.awb.gains.red, 0, 0x3ff);
+	params->others.awb_gain_config.gain_green_r =
+		std::clamp<int>(256 * frameContext.awb.gains.green, 0, 0x3ff);
 
 	/* Update the gains. */
 	params->module_cfg_update |= RKISP1_CIF_ISP_MODULE_AWB_GAIN;
-- 
2.43.0