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meson: ipa: Add mapping for pipeline handler to mojom interface file

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Allow an arbitrary mapping between the pipeline handler and IPA mojom
interface file in the build system. This removes the 1:1 mapping of
pipeline handler name to mojom filename, and allows more flexibility to
pipeline developers.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
This commit is contained in:
Naushir Patuck 2023-05-03 13:20:23 +01:00 • committed by Laurent Pinchart
parent 8258bd6ad6
commit 312e9910ba
2 changed files with 48 additions and 25 deletions
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40
Documentation/guides/ipa.rst
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@ -19,6 +19,16 @@ connect to, in order to receive data from the IPA asynchronously. In addition,
it contains any custom data structures that the pipeline handler and IPA may
pass to each other.
It is possible to use the same IPA interface with multiple pipeline handlers
on different hardware platforms. Generally in such cases, these platforms would
have a common hardware ISP pipeline. For instance, the rkisp1 pipeline handler
supports both the RK3399 and the i.MX8MP as they integrate the same ISP.
However, the i.MX8MP has a more complex camera pipeline, which may call for a
dedicated pipeline handler in the future. As the ISP is the same as for RK3399,
the same IPA interface could be used for both pipeline handlers. The build files
provide a mapping from pipeline handler to the IPA interface name as detailed in
:ref:`compiling-section`.
The IPA protocol refers to the agreement between the pipeline handler and the
IPA regarding the expected response(s) from the IPA for given calls to the IPA.
This protocol doesn't need to be declared anywhere in code, but it shall be
@ -43,7 +53,7 @@ interface definition is thus written by the pipeline handler author, based on
how they design the interactions between the pipeline handler and the IPA.
The entire IPA interface, including the functions, signals, and any custom
structs shall be defined in a file named {pipeline_name}.mojom under
structs shall be defined in a file named {interface_name}.mojom under
include/libcamera/ipa/.
.. _mojo Interface Definition Language: https://chromium.googlesource.com/chromium/src.git/+/master/mojo/public/tools/bindings/README.md
@ -150,7 +160,7 @@ and the Event IPA interface, which describes the signals received by the
pipeline handler that the IPA can emit. Both must be defined. This section
focuses on the Main IPA interface.
The main interface must be named as IPA{pipeline_name}Interface.
The main interface must be named as IPA{interface_name}Interface.
The functions that the pipeline handler can call from the IPA may be
synchronous or asynchronous. Synchronous functions do not return until the IPA
@ -243,7 +253,7 @@ then it may be empty. These emissions are meant to notify the pipeline handler
of some event, such as request data is ready, and *must not* be used to drive
the camera pipeline from the IPA.
The event interface must be named as IPA{pipeline_name}EventInterface.
The event interface must be named as IPA{interface_name}EventInterface.
Functions defined in the event interface are implicitly asynchronous.
Thus they cannot return any value. Specifying the [async] tag is not
@ -266,38 +276,42 @@ The following is an example of an event interface definition:
setStaggered(libcamera.ControlList controls);
};
.. _compiling-section:
Compiling the IPA interface
---------------------------
After the IPA interface is defined in include/libcamera/ipa/{pipeline_name}.mojom,
After the IPA interface is defined in include/libcamera/ipa/{interface_name}.mojom,
an entry for it must be added in meson so that it can be compiled. The filename
must be added to the ipa_mojom_files object in include/libcamera/ipa/meson.build.
must be added to the pipeline_ipa_mojom_mapping variable in
include/libcamera/ipa/meson.build. This variable maps the pipeline handler name
to its IPA interface file.
For example, adding the raspberrypi.mojom file to meson:
.. code-block:: none
ipa_mojom_files = [
'raspberrypi.mojom',
pipeline_ipa_mojom_mapping = [
'rpi/vc4': 'raspberrypi.mojom',
]
This will cause the mojo data definition file to be compiled. Specifically, it
generates five files:
- a header describing the custom data structures, and the complete IPA
interface (at {$build_dir}/include/libcamera/ipa/{pipeline}_ipa_interface.h)
interface (at {$build_dir}/include/libcamera/ipa/{interface}_ipa_interface.h)
- a serializer implementing de/serialization for the custom data structures (at
{$build_dir}/include/libcamera/ipa/{pipeline}_ipa_serializer.h)
{$build_dir}/include/libcamera/ipa/{interface}_ipa_serializer.h)
- a proxy header describing a specialized IPA proxy (at
{$build_dir}/include/libcamera/ipa/{pipeline}_ipa_proxy.h)
{$build_dir}/include/libcamera/ipa/{interface}_ipa_proxy.h)
- a proxy source implementing the IPA proxy (at
{$build_dir}/src/libcamera/proxy/{pipeline}_ipa_proxy.cpp)
{$build_dir}/src/libcamera/proxy/{interface}_ipa_proxy.cpp)
- a proxy worker source implementing the other end of the IPA proxy (at
{$build_dir}/src/libcamera/proxy/worker/{pipeline}_ipa_proxy_worker.cpp)
{$build_dir}/src/libcamera/proxy/worker/{interface}_ipa_proxy_worker.cpp)
The IPA proxy serves as the layer between the pipeline handler and the IPA, and
handles threading vs isolation transparently. The pipeline handler and the IPA
@ -312,7 +326,7 @@ file, the following header must be included:
.. code-block:: C++
#include <libcamera/ipa/{pipeline_name}_ipa_interface.h>
#include <libcamera/ipa/{interface_name}_ipa_interface.h>
The POD types of the structs simply become their C++ counterparts, eg. uint32
in mojo will become uint32_t in C++. mojo map becomes C++ std::map, and mojo