libcamera: camera: Remove the prepared state

With the FrameBuffer rework completed there is no reason to keep the
camera prepared state around as buffer allocations are now decoupled
from the camera state. Remove the camera state simplifying the API.

Signed-off-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

6 files changed, 22 insertions, 116 deletions

diff --git a/src/android/camera_device.cpp b/src/android/camera_device.cpp
index 49321db0..a98fd744 100644
--- a/src/android/camera_device.cpp
+++ b/src/android/camera_device.cpp
@@ -77,8 +77,6 @@ int CameraDevice::open()
 void CameraDevice::close()
 {
 	camera_->stop();
-
-	camera_->freeBuffers();
 	camera_->release();
 
 	running_ = false;
@@ -690,16 +688,9 @@ void CameraDevice::processCaptureRequest(camera3_capture_request_t *camera3Reque
 
 	/* Start the camera if that's the first request we handle. */
 	if (!running_) {
-		int ret = camera_->allocateBuffers();
-		if (ret) {
-			LOG(HAL, Error) << "Failed to allocate buffers";
-			return;
-		}
-
-		ret = camera_->start();
+		int ret = camera_->start();
 		if (ret) {
 			LOG(HAL, Error) << "Failed to start camera";
-			camera_->freeBuffers();
 			return;
 		}
 
diff --git a/src/cam/capture.cpp b/src/cam/capture.cpp
index 738fa1c2..7d970f99 100644
--- a/src/cam/capture.cpp
+++ b/src/cam/capture.cpp
@@ -42,12 +42,6 @@ int Capture::run(EventLoop *loop, const OptionsParser::Options &options)
 		return ret;
 	}
 
-	ret = camera_->allocateBuffers();
-	if (ret) {
-		std::cerr << "Failed to allocate buffers" << std::endl;
-		return ret;
-	}
-
 	camera_->requestCompleted.connect(this, &Capture::requestComplete);
 
 	if (options.isSet(OptFile)) {
@@ -67,8 +61,6 @@ int Capture::run(EventLoop *loop, const OptionsParser::Options &options)
 		writer_ = nullptr;
 	}
 
-	camera_->freeBuffers();
-
 	delete allocator;
 
 	return ret;
diff --git a/src/libcamera/camera.cpp b/src/libcamera/camera.cpp
index f3a7578d..79a5f994 100644
--- a/src/libcamera/camera.cpp
+++ b/src/libcamera/camera.cpp
@@ -275,15 +275,13 @@ std::size_t CameraConfiguration::size() const
  * \section camera_operation Operating the Camera
  *
  * An application needs to perform a sequence of operations on a camera before
- * it is ready to process requests. The camera needs to be acquired, configured
- * and resources allocated or imported to prepare the camera for capture. Once
- * started the camera can process requests until it is stopped. When an
- * application is done with a camera all resources allocated need to be freed
- * and the camera released.
+ * it is ready to process requests. The camera needs to be acquired and
+ * configured to prepare the camera for capture. Once started the camera can
+ * process requests until it is stopped. When an application is done with a
+ * camera, the camera needs to be released.
  *
  * An application may start and stop a camera multiple times as long as it is
- * not released. The camera may also be reconfigured provided that all
- * resources allocated are freed prior to the reconfiguration.
+ * not released. The camera may also be reconfigured.
  *
  * \subsection Camera States
  *
@@ -297,7 +295,6 @@ std::size_t CameraConfiguration::size() const
  *   node [shape = doublecircle ]; Available;
  *   node [shape = circle ]; Acquired;
  *   node [shape = circle ]; Configured;
- *   node [shape = circle ]; Prepared;
  *   node [shape = circle ]; Running;
  *
  *   Available -> Available [label = "release()"];
@@ -307,14 +304,10 @@ std::size_t CameraConfiguration::size() const
  *   Acquired -> Configured [label = "configure()"];
  *
  *   Configured -> Available [label = "release()"];
- *   Configured -> Configured [label = "configure()"];
- *   Configured -> Prepared [label = "allocateBuffers()"];
+ *   Configured -> Configured [label = "configure(), createRequest()"];
+ *   Configured -> Running [label = "start()"];
  *
- *   Prepared -> Configured [label = "freeBuffers()"];
- *   Prepared -> Prepared [label = "createRequest()"];
- *   Prepared -> Running [label = "start()"];
- *
- *   Running -> Prepared [label = "stop()"];
+ *   Running -> Configured [label = "stop()"];
  *   Running -> Running [label = "createRequest(), queueRequest()"];
  * }
  * \enddot
@@ -330,19 +323,14 @@ std::size_t CameraConfiguration::size() const
  * Configured state.
  *
  * \subsubsection Configured
- * The camera is configured and ready for the application to prepare it with
- * resources. The camera may be reconfigured multiple times until resources
- * are provided and the state progresses to Prepared.
- *
- * \subsubsection Prepared
- * The camera has been configured and provided with resources and is ready to be
- * started. The application may free the camera's resources to get back to the
- * Configured state or start() it to progress to the Running state.
+ * The camera is configured and ready to be started. The application may
+ * release() the camera and to get back to the Available state or start()
+ * it to progress to the Running state.
  *
  * \subsubsection Running
  * The camera is running and ready to process requests queued by the
  * application. The camera remains in this state until it is stopped and moved
- * to the Prepared state.
+ * to the Configured state.
  */
 
 /**
@@ -420,7 +408,6 @@ static const char *const camera_state_names[] = {
 	"Available",
 	"Acquired",
 	"Configured",
-	"Prepared",
 	"Running",
 };
 
@@ -465,8 +452,6 @@ bool Camera::stateIs(State state) const
  *
  * \todo Deal with pending requests if the camera is disconnected in a
  * running state.
- * \todo Update comment about Running state when importing buffers as well as
- * allocating them are supported.
  */
 void Camera::disconnect()
 {
@@ -474,11 +459,11 @@ void Camera::disconnect()
 
 	/*
 	 * If the camera was running when the hardware was removed force the
-	 * state to Prepared to allow applications to call freeBuffers() and
-	 * release() before deleting the camera.
+	 * state to Configured state to allow applications to free resources
+	 * and call release() before deleting the camera.
 	 */
 	if (state_ == CameraRunning)
-		state_ = CameraPrepared;
+		state_ = CameraConfigured;
 
 	disconnected_ = true;
 	disconnected.emit(this);
@@ -703,53 +688,6 @@ int Camera::configure(CameraConfiguration *config)
 }
 
 /**
- * \brief Allocate buffers for all configured streams
- *
- * This function affects the state of the camera, see \ref camera_operation.
- *
- * \return 0 on success or a negative error code otherwise
- * \retval -ENODEV The camera has been disconnected from the system
- * \retval -EACCES The camera is not in a state where buffers can be allocated
- * \retval -EINVAL The configuration is not valid
- */
-int Camera::allocateBuffers()
-{
-	if (disconnected_)
-		return -ENODEV;
-
-	if (!stateIs(CameraConfigured))
-		return -EACCES;
-
-	if (activeStreams_.empty()) {
-		LOG(Camera, Error)
-			<< "Can't allocate buffers without streams";
-		return -EINVAL;
-	}
-
-	state_ = CameraPrepared;
-
-	return 0;
-}
-
-/**
- * \brief Release all buffers from allocated pools in each stream
- *
- * This function affects the state of the camera, see \ref camera_operation.
- *
- * \return 0 on success or a negative error code otherwise
- * \retval -EACCES The camera is not in a state where buffers can be freed
- */
-int Camera::freeBuffers()
-{
-	if (!stateIs(CameraPrepared))
-		return -EACCES;
-
-	state_ = CameraConfigured;
-
-	return 0;
-}
-
-/**
  * \brief Create a request object for the camera
  * \param[in] cookie Opaque cookie for application use
  *
@@ -764,14 +702,14 @@ int Camera::freeBuffers()
  * The ownership of the returned request is passed to the caller, which is
  * responsible for either queueing the request or deleting it.
  *
- * This function shall only be called when the camera is in the Prepared
+ * This function shall only be called when the camera is in the Configured
  * or Running state, see \ref camera_operation.
  *
  * \return A pointer to the newly created request, or nullptr on error
  */
 Request *Camera::createRequest(uint64_t cookie)
 {
-	if (disconnected_ || !stateBetween(CameraPrepared, CameraRunning))
+	if (disconnected_ || !stateBetween(CameraConfigured, CameraRunning))
 		return nullptr;
 
 	return new Request(this, cookie);
@@ -842,7 +780,7 @@ int Camera::start()
 	if (disconnected_)
 		return -ENODEV;
 
-	if (!stateIs(CameraPrepared))
+	if (!stateIs(CameraConfigured))
 		return -EACCES;
 
 	LOG(Camera, Debug) << "Starting capture";
@@ -885,7 +823,7 @@ int Camera::stop()
 
 	LOG(Camera, Debug) << "Stopping capture";
 
-	state_ = CameraPrepared;
+	state_ = CameraConfigured;
 
 	pipe_->stop(this);
 
diff --git a/src/libcamera/framebuffer_allocator.cpp b/src/libcamera/framebuffer_allocator.cpp
index 57789b24..207a13bd 100644
--- a/src/libcamera/framebuffer_allocator.cpp
+++ b/src/libcamera/framebuffer_allocator.cpp
@@ -116,8 +116,7 @@ FrameBufferAllocator::~FrameBufferAllocator()
  */
 int FrameBufferAllocator::allocate(Stream *stream)
 {
-	if (camera_->state_ != Camera::CameraConfigured &&
-	    camera_->state_ != Camera::CameraPrepared) {
+	if (camera_->state_ != Camera::CameraConfigured) {
 		LOG(Allocator, Error)
 			<< "Camera must be in the configured state to allocate buffers";
 		return -EACCES;
@@ -163,7 +162,7 @@ int FrameBufferAllocator::allocate(Stream *stream)
  */
 int FrameBufferAllocator::free(Stream *stream)
 {
-	if (camera_->state_ != Camera::CameraConfigured && camera_->state_ != Camera::CameraPrepared) {
+	if (camera_->state_ != Camera::CameraConfigured) {
 		LOG(Allocator, Error)
 			<< "Camera must be in the configured state to free buffers";
 		return -EACCES;
diff --git a/src/qcam/main_window.cpp b/src/qcam/main_window.cpp
index 047bf15e..1d9c756f 100644
--- a/src/qcam/main_window.cpp
+++ b/src/qcam/main_window.cpp
@@ -172,13 +172,6 @@ int MainWindow::startCapture()
 
 	adjustSize();
 
-	ret = camera_->allocateBuffers();
-	if (ret) {
-		std::cerr << "Failed to allocate buffers"
-			  << std::endl;
-		return ret;
-	}
-
 	ret = allocator_->allocate(stream);
 	if (ret < 0) {
 		std::cerr << "Failed to allocate capture buffers" << std::endl;
@@ -244,7 +237,6 @@ error:
 	}
 	mappedBuffers_.clear();
 
-	camera_->freeBuffers();
 	return ret;
 }
 
@@ -264,7 +256,6 @@ void MainWindow::stopCapture()
 	}
 	mappedBuffers_.clear();
 
-	camera_->freeBuffers();
 	isCapturing_ = false;
 
 	config_.reset();
diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp
index 10db15d6..44cb4e7c 100644
--- a/src/v4l2/v4l2_camera.cpp
+++ b/src/v4l2/v4l2_camera.cpp
@@ -121,10 +121,6 @@ int V4L2Camera::configure(StreamConfiguration *streamConfigOut,
 
 int V4L2Camera::allocBuffers(unsigned int count)
 {
-	int ret = camera_->allocateBuffers();
-	if (ret)
-		return ret == -EACCES ? -EBUSY : ret;
-
 	Stream *stream = *camera_->streams().begin();
 
 	return bufferAllocator_->allocate(stream);
@@ -134,7 +130,6 @@ void V4L2Camera::freeBuffers()
 {
 	Stream *stream = *camera_->streams().begin();
 	bufferAllocator_->free(stream);
-	camera_->freeBuffers();
 }
 
 FileDescriptor V4L2Camera::getBufferFd(unsigned int index)