[libcamera-devel] [PATCH] libcamera: camera: Reset request sequence number on stop/start

[Umang Jain]

We now have V4L2VideoDevice ensuring that sensor sequence numbers
start from zero [1], and we desire that these should match the Request
sequence number as well.

[1] 1c9dc0fd89cf ("libcamera: v4l2_videodevice: Identify non-zero stream starts")

Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
 src/libcamera/camera.cpp           | 4 +++-
 src/libcamera/pipeline_handler.cpp | 2 ++
 src/libcamera/request.cpp          | 4 ++--
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index 713543fd..f8150dcd 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -497,7 +497,7 @@ Camera::Private::~Private()
  * facilitate debugging of internal request usage.
  *
  * The requestSequence_ tracks the number of requests queued to a camera
- * over its lifetime.
+ * over a single capture session.
  */
 
 static const char *const camera_state_names[] = {
@@ -1181,6 +1181,8 @@ int Camera::start(const ControlList *controls)
 
 	LOG(Camera, Debug) << "Starting capture";
 
+	ASSERT(d->requestSequence_ == 0);
+
 	ret = d->pipe_->invokeMethod(&PipelineHandler::start,
 				     ConnectionTypeBlocking, this, controls);
 	if (ret)
diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 7ebd76ad..67540533 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -312,6 +312,8 @@ void PipelineHandler::stop(Camera *camera)
 	/* Make sure no requests are pending. */
 	Camera::Private *data = camera->_d();
 	ASSERT(data->queuedRequests_.empty());
+
+	data->requestSequence_ = 0;
 }
 
 /**
diff --git a/src/libcamera/request.cpp b/src/libcamera/request.cpp
index 51d74b29..07613cb3 100644
--- a/src/libcamera/request.cpp
+++ b/src/libcamera/request.cpp
@@ -526,8 +526,8 @@ FrameBuffer *Request::findBuffer(const Stream *stream) const
  *
  * When requests are queued, they are given a sequential number to track the
  * order in which requests are queued to a camera. This number counts all
- * requests given to a camera through its lifetime, and is not reset to zero
- * between camera stop/start sequences.
+ * requests given to a camera and is reset to zero between camera stop/start
+ * sequences.
  *
  * It can be used to support debugging and identifying the flow of requests
  * through a pipeline, but does not guarantee to represent the sequence number
-- 
2.31.1