libcamera: pipeline: extend pipelines to support stream configuration

All streams which are to be used for capture need to be configured at
the same time. This allows the pipeline handler to take any dependencies
between the different streams and their configuration into account when
setting up the hardware.

Extend the pipeline API and all pipeline implementations with two new
functions, one to read a default configuration and one to set a new
configuration. Both functions operate on a group of streams which the
pipeline handler should consider when performing the operations.

In the current implemented pipelines this is rather easy as they only
have one stream each per camera. Furthermore as there is yet no way for
the pipeline handlers to interact with the hardware all they do is
return a null format, log that a default configuration has been
requested and log that a new configuration has been set. Future work
based on more components are needed to make the pipelines return a good
default format and actually interact with the hardware.

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

1 files changed, 34 insertions, 0 deletions

diff --git a/src/libcamera/pipeline_handler.cpp b/src/libcamera/pipeline_handler.cpp
index 1c864079..3a560e10 100644
--- a/src/libcamera/pipeline_handler.cpp
+++ b/src/libcamera/pipeline_handler.cpp
@@ -75,6 +75,40 @@ PipelineHandler::~PipelineHandler()
 {
 };
 
+
+/**
+ * \fn PipelineHandler::streamConfiguration()
+ * \brief Retrieve a group of stream configurations for a specified camera
+ * \param[in] camera The camera to fetch default configuration from
+ * \param[in] streams An array of streams to fetch information about
+ *
+ * Retrieve the species camera's default configuration for a specified group of
+ * streams. The caller shall populate the \a streams array with the streams it
+ * wish to fetch the configuration from. The map of streams and configuration
+ * returned can then be examined by the caller to learn about the defualt
+ * parameters for the specified streams.
+ *
+ * The intended companion to this is \a configureStreams() which can be used to
+ * change the group of streams parameters.
+ *
+ * \return A map of successfully retrieved streams and configurations or an
+ * empty map on error.
+ */
+
+/**
+ * \fn PipelineHandler::configureStreams()
+ * \brief Configure a group of streams for capture
+ * \param[in] camera The camera to configure
+ * \param[in] config A map of stream configurations to apply
+ *
+ * Configure the specified group of streams for \a camera according to the
+ * configuration specified in \a configs. The intended caller of this interface
+ * is the Camera class which will receive configuration to apply from the
+ * application.
+ *
+ * \return 0 on success or a negative error code on error.
+ */
+
 /**
  * \fn PipelineHandler::match(DeviceEnumerator *enumerator)
  * \brief Match media devices and create camera instances