[libcamera-devel] [PATCH v2 3/3] libcamera: pipeline: raspberrypi: Update sensor's V4L2_CID_NOTIFY_GAINS control

[David Plowman]

If the sensor exposes the V4L2_CID_NOTIFY_GAINS control, assume it
means the sensor wants to be told the latest colour gains.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 .../pipeline/raspberrypi/raspberrypi.cpp      | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
index b5c687da..0d4b5a57 100644
--- a/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
+++ b/src/libcamera/pipeline/raspberrypi/raspberrypi.cpp
@@ -1495,6 +1495,32 @@ void RPiCameraData::statsMetadataComplete(uint32_t bufferId, const ControlList &
 	Request *request = requestQueue_.front();
 	request->metadata().merge(controls);
 
+	/*
+	 * If the sensor has the V4L2_CID_NOTIFY_GAIN control then it wants
+	 * to be notified of the latest colour gains.
+	 */
+	auto it = sensor_->controls().find(V4L2_CID_NOTIFY_GAINS);
+	if (it != sensor_->controls().end()) {
+		if (controls.contains(libcamera::controls::ColourGains)) {
+			libcamera::Span<const float> colourGains = controls.get(libcamera::controls::ColourGains);
+			/*
+			 * This control is a linear gain value where the default is
+			 * defined to correspond to a gain of 1. The order of the gains
+			 * is always B, Gb, Gr, R.
+			 */
+			int unity = it->second.def().get<int32_t>();
+			ControlList ctrls(sensor_->controls());
+			int32_t gains[4] = { static_cast<int32_t>(colourGains[1] * unity),
+					     unity, unity,
+					     static_cast<int32_t>(colourGains[0] * unity) };
+			ControlValue c(Span<const uint8_t>{ reinterpret_cast<uint8_t *>(gains),
+							    sizeof(gains) });
+			ctrls.set(V4L2_CID_NOTIFY_GAINS, c);
+
+			sensor_->setControls(&ctrls);
+		}
+	}
+
 	state_ = State::IpaComplete;
 	handleState();
 }
-- 
2.30.2