[PATCH] libcamera: reserve frame sequence reported from the hardware

[Harvey Yang]

From: Yudhistira Erlandinata <yerlandinata at chromium.org>

Originally libcamera resets the sequence to 0 on streamOn. However,
However, there are occasions when the user needs the original
hardware sequence to query processing information of the particular
frame. The patch reserves the hwSequence in the FrameMetadata.

Signed-off-by: Yudhistira Erlandinata <yerlandinata at chromium.org>
Co-developed-by: Harvey Yang <chenghaoyang at chromium.org>
Signed-off-by: Harvey Yang <chenghaoyang at chromium.org>
---
 include/libcamera/framebuffer.h    | 1 +
 src/libcamera/framebuffer.cpp      | 9 +++++++++
 src/libcamera/v4l2_videodevice.cpp | 1 +
 3 files changed, 11 insertions(+)

diff --git a/include/libcamera/framebuffer.h b/include/libcamera/framebuffer.h
index ff8392430..fccfaa82a 100644
--- a/include/libcamera/framebuffer.h
+++ b/include/libcamera/framebuffer.h
@@ -34,6 +34,7 @@ struct FrameMetadata {
 
 	Status status;
 	unsigned int sequence;
+	unsigned int hwSequence;
 	uint64_t timestamp;
 
 	Span<Plane> planes() { return planes_; }
diff --git a/src/libcamera/framebuffer.cpp b/src/libcamera/framebuffer.cpp
index 826848f75..d9d6294bc 100644
--- a/src/libcamera/framebuffer.cpp
+++ b/src/libcamera/framebuffer.cpp
@@ -86,6 +86,15 @@ LOG_DEFINE_CATEGORY(Buffer)
  * Gaps in the sequence numbers indicate dropped frames.
  */
 
+/**
+ * \var FrameMetadata::hwSequence
+ * \brief The real hardware Frame sequence number
+ *
+ * \a FrameMetadata::sequence auto-corrects the initial value to zero on frame
+ * start. This value keeps the original hardware sequence to allow users to
+ * query processing information of particular frames.
+ */
+
 /**
  * \var FrameMetadata::timestamp
  * \brief Time when the frame was captured
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index 14eba0561..9bc677edf 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -1862,6 +1862,7 @@ FrameBuffer *V4L2VideoDevice::dequeueBuffer()
 			? FrameMetadata::FrameError
 			: FrameMetadata::FrameSuccess;
 	metadata.sequence = buf.sequence;
+	metadata.hwSequence = buf.sequence;
 	metadata.timestamp = buf.timestamp.tv_sec * 1000000000ULL
 			   + buf.timestamp.tv_usec * 1000ULL;
 
-- 
2.47.0.rc1.288.g06298d1525-goog