[libcamera-devel] [PATCH v2 3/5] ipa: core: Move documentation from cpp file back into the mojom file

[Paul Elder]

Move the documentation back to the mojom file from the cpp file. While
at it, move the documentation for IPAInterface::init() and
IPAInterface::stop() to the IPA guide.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 Documentation/guides/ipa.rst     |   6 +
 include/libcamera/ipa/core.mojom | 200 ++++++++++++++++++++++++++++---
 2 files changed, 190 insertions(+), 16 deletions(-)

diff --git a/Documentation/guides/ipa.rst b/Documentation/guides/ipa.rst
index 6195b2b7..c612470f 100644
--- a/Documentation/guides/ipa.rst
+++ b/Documentation/guides/ipa.rst
@@ -166,6 +166,12 @@ At a minimum, the following three functions must be present (and implemented):
 All three of these functions are synchronous. The parameters for start() and
 init() may be customized.
 
+init() initializes the IPA interface. It shall be called before any other
+function of the IPAInterface.
+
+stop() informs the IPA module that the camera is stopped. The IPA module shall
+release resources prepared in start().
+
 A configure() method is recommended. Any ControlInfoMap instances that will be
 used by the IPA must be sent to the IPA from the pipeline handler, at configure
 time, for example.
diff --git a/include/libcamera/ipa/core.mojom b/include/libcamera/ipa/core.mojom
index 34a799c2..b32f3093 100644
--- a/include/libcamera/ipa/core.mojom
+++ b/include/libcamera/ipa/core.mojom
@@ -2,6 +2,11 @@
 
 module libcamera;
 
+/**
+ * \file core_ipa_interface.h
+ * \brief libcamera structs for IPAs
+ */
+
 /*
  * Things that can be defined here (and in other mojom files):
  * - consts
@@ -78,6 +83,116 @@ module libcamera;
 	uint32 height;
 };
 
+/**
+ * \struct IPACameraSensorInfo
+ * \brief Report the image sensor characteristics
+ *
+ * The structure reports image sensor characteristics used by IPA modules to
+ * tune their algorithms based on the image sensor model currently in use and
+ * its configuration.
+ *
+ * The reported information describes the sensor's intrinsics characteristics,
+ * such as its pixel array size and the sensor model name, as well as
+ * information relative to the currently configured mode, such as the produced
+ * image size and the bit depth of the requested image format.
+ *
+ * Instances of this structure are meant to be assembled by the CameraSensor
+ * class by inspecting the sensor static properties as well as information
+ * relative to the current configuration.
+ */
+
+/**
+ * \var IPACameraSensorInfo::model
+ * \brief The image sensor model name
+ *
+ * The sensor model name is a free-formed string that uniquely identifies the
+ * sensor model.
+ */
+
+/**
+ * \var IPACameraSensorInfo::bitsPerPixel
+ * \brief The number of bits per pixel of the image format produced by the
+ * image sensor
+ */
+
+/**
+ * \var IPACameraSensorInfo::activeAreaSize
+ * \brief The size of the pixel array active area of the sensor
+ */
+
+/**
+ * \var IPACameraSensorInfo::analogCrop
+ * \brief The portion of the pixel array active area which is read-out and
+ * processed
+ *
+ * The analog crop rectangle top-left corner is defined as the displacement
+ * from the top-left corner of the pixel array active area. The rectangle
+ * horizontal and vertical sizes define the portion of the pixel array which
+ * is read-out and provided to the sensor's internal processing pipeline, before
+ * any pixel sub-sampling method, such as pixel binning, skipping and averaging
+ * take place.
+ */
+
+/**
+ * \var IPACameraSensorInfo::outputSize
+ * \brief The size of the images produced by the camera sensor
+ *
+ * The output image size defines the horizontal and vertical sizes of the images
+ * produced by the image sensor. The output image size is defined as the end
+ * result of the sensor's internal image processing pipeline stages, applied on
+ * the pixel array portion defined by the analog crop rectangle. Each image
+ * processing stage that performs pixel sub-sampling techniques, such as pixel
+ * binning or skipping, or perform any additional digital scaling concur in the
+ * definition of the output image size.
+ */
+
+/**
+ * \var IPACameraSensorInfo::pixelRate
+ * \brief The number of pixels produced in a second
+ *
+ * To obtain the read-out time in seconds of a full line:
+ *
+ * \verbatim
+       lineDuration(s) = lineLength(pixels) / pixelRate(pixels per second)
+   \endverbatim
+ */
+
+/**
+ * \var IPACameraSensorInfo::lineLength
+ * \brief Total line length in pixels
+ *
+ * The total line length in pixel clock periods, including blanking.
+ */
+
+/**
+ * \var IPACameraSensorInfo::minFrameLength
+ * \brief The minimum allowable frame length in units of lines
+ *
+ * The sensor frame length comprises of active output lines and blanking lines
+ * in a frame. The minimum frame length value dictates the minimum allowable
+ * frame duration of the sensor mode.
+ *
+ * To obtain the minimum frame duration:
+ *
+ * \verbatim
+       frameDuration(s) = minFrameLength(lines) * lineLength(pixels) / pixelRate(pixels per second)
+   \endverbatim
+ */
+
+/**
+ * \var IPACameraSensorInfo::maxFrameLength
+ * \brief The maximum allowable frame length in units of lines
+ *
+ * The sensor frame length comprises of active output lines and blanking lines
+ * in a frame. The maximum frame length value dictates the maximum allowable
+ * frame duration of the sensor mode.
+ *
+ * To obtain the maximum frame duration:
+ *
+ * \verbatim
+       frameDuration(s) = maxFrameLength(lines) * lineLength(pixels) / pixelRate(pixels per second)
+   \endverbatim
+ */
 struct IPACameraSensorInfo {
 	string model;
 
@@ -94,35 +209,88 @@ struct IPACameraSensorInfo {
 	uint32 maxFrameLength;
 };
 
+/**
+ * \struct IPABuffer
+ * \brief Buffer information for the IPA interface
+ *
+ * The IPABuffer structure associates buffer memory with a unique ID. It is
+ * used to map buffers to the IPA with IPAInterface::mapBuffers(), after which
+ * buffers will be identified by their ID in the IPA interface.
+ */
+
+/**
+ * \var IPABuffer::id
+ * \brief The buffer unique ID
+ *
+ * Buffers mapped to the IPA are identified by numerical unique IDs. The IDs
+ * are chosen by the pipeline handler to fulfil the following constraints:
+ *
+ * - IDs shall be positive integers different than zero
+ * - IDs shall be unique among all mapped buffers
+ *
+ * When buffers are unmapped with IPAInterface::unmapBuffers() their IDs are
+ * freed and may be reused for new buffer mappings.
+ */
+
+/**
+ * \var IPABuffer::planes
+ * \brief The buffer planes description
+ *
+ * Stores the dmabuf handle and length for each plane of the buffer.
+ */
 struct IPABuffer {
 	uint32 id;
 	[hasFd] array<FrameBuffer.Plane> planes;
 };
 
+/**
+ * \struct IPASettings
+ * \brief IPA interface initialization settings
+ *
+ * The IPASettings structure stores data passed to the IPAInterface::init()
+ * function. The data contains settings that don't depend on a particular camera
+ * or pipeline configuration and are valid for the whole life time of the IPA
+ * interface.
+ */
+
+/**
+ * \var IPASettings::configurationFile
+ * \brief The name of the IPA configuration file
+ *
+ * This field may be an empty string if the IPA doesn't require a configuration
+ * file.
+ */
+
+/**
+ * \var IPASettings::sensorModel
+ * \brief The sensor model name
+ *
+ * Provides the sensor model name to the IPA.
+ */
 struct IPASettings {
 	string configurationFile;
 	string sensorModel;
 };
 
-struct IPAStream {
-	uint32 pixelFormat;
-	Size size;
-};
-
 /**
- * \fn IPAInterface::init()
- * \brief Initialise the IPAInterface
- * \param[in] settings The IPA initialization settings
+ * \struct IPAStream
+ * \brief Stream configuration for the IPA interface
  *
- * This function initializes the IPA interface. It shall be called before any
- * other function of the IPAInterface. The \a settings carry initialization
- * parameters that are valid for the whole life time of the IPA interface.
+ * The IPAStream structure stores stream configuration parameters needed by the
+ * IPAInterface::configure() method. It mirrors the StreamConfiguration class
+ * that is not suitable for this purpose due to not being serializable.
  */
 
 /**
- * \fn IPAInterface::stop()
- * \brief Stop the IPA
- *
- * This method informs the IPA module that the camera is stopped. The IPA module
- * shall release resources prepared in start().
+ * \var IPAStream::pixelFormat
+ * \brief The stream pixel format
+ */
+
+/**
+ * \var IPAStream::size
+ * \brief The stream size in pixels
  */
+struct IPAStream {
+	uint32 pixelFormat;
+	Size size;
+};
-- 
2.27.0