[libcamera-devel] [PATCH 2/3] libcamera: ipu3: Report sensor timestamp

[Jacopo Mondi]

Report the sensor's timestamp in the Request metadata by using the
CIO2 buffer timestamp as a good-enough approximation.

The buffer's timestamp is recorded at DMA-transfer time, and it does not
theoretically matches the 'start of exposure' definition, but when used
to compare two consecutive frames it gives an acceptable estimation of
the sensor frame period duration.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 src/libcamera/pipeline/ipu3/ipu3.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 519cad4f8148..d52e24f847a2 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -1251,6 +1251,15 @@ void IPU3CameraData::cio2BufferReady(FrameBuffer *buffer)
 
 	Request *request = info->request;
 
+	/*
+	 * Record the sensor's timestamp in the request metadata.
+	 *
+	 * \todo The sensor timestamp should be better estimated by connecting
+	 * to the V4L2Device::frameStart signal.
+	 */
+	request->metadata().set(controls::SensorTimestamp,
+				buffer->metadata().timestamp);
+
 	/* If the buffer is cancelled force a complete of the whole request. */
 	if (buffer->metadata().status == FrameMetadata::FrameCancelled) {
 		for (auto it : request->buffers())
-- 
2.31.1