From patchwork Fri Jul 16 12:19:02 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jacopo Mondi X-Patchwork-Id: 13028 Return-Path: X-Original-To: parsemail@patchwork.libcamera.org Delivered-To: parsemail@patchwork.libcamera.org Received: from lancelot.ideasonboard.com (lancelot.ideasonboard.com [92.243.16.209]) by patchwork.libcamera.org (Postfix) with ESMTPS id 54C8DC3226 for ; Fri, 16 Jul 2021 12:18:23 +0000 (UTC) Received: from lancelot.ideasonboard.com (localhost [IPv6:::1]) by lancelot.ideasonboard.com (Postfix) with ESMTP id C7B926853C; Fri, 16 Jul 2021 14:18:21 +0200 (CEST) Received: from relay5-d.mail.gandi.net (relay5-d.mail.gandi.net [217.70.183.197]) by lancelot.ideasonboard.com (Postfix) with ESMTPS id 6975768536 for ; Fri, 16 Jul 2021 14:18:20 +0200 (CEST) Received: (Authenticated sender: jacopo@jmondi.org) by relay5-d.mail.gandi.net (Postfix) with ESMTPSA id 88E301C000C; Fri, 16 Jul 2021 12:18:19 +0000 (UTC) From: Jacopo Mondi To: libcamera-devel@lists.libcamera.org Date: Fri, 16 Jul 2021 14:19:02 +0200 Message-Id: <20210716121902.48338-1-jacopo@jmondi.org> X-Mailer: git-send-email 2.32.0 MIME-Version: 1.0 Subject: [libcamera-devel] [PATCH v2] ipa: core.mojom: Rework core file documentation X-BeenThere: libcamera-devel@lists.libcamera.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: libcamera-devel-bounces@lists.libcamera.org Sender: "libcamera-devel" The comment block at the beginning of the core.mojom file is meant to provide an overview of how to use libcamera defined types in the definition of mojom interfaces. As the IPA/IPC interface definition mechanism evolved, the documentation has not been updated accordingly. Update the file comments to match the most recent IPA/IPC interface definition and generation mechanism. Signed-off-by: Jacopo Mondi --- v1->v2: - Address Paul's comment and clarify points that were not clear to me when I wrote v1 :) - (de)serializers implementations go in ipa_data_serializer.cpp - types used as array/map members do not require a mojom definition - remove duplications - s/the library/libcamera - While at it, make all statements start with a capital letter and end without a full-stop. --- include/libcamera/ipa/core.mojom | 67 +++++++++++++++++++------------- 1 file changed, 40 insertions(+), 27 deletions(-) -- 2.32.0 diff --git a/include/libcamera/ipa/core.mojom b/include/libcamera/ipa/core.mojom index b32f30939454..39fac624658a 100644 --- a/include/libcamera/ipa/core.mojom +++ b/include/libcamera/ipa/core.mojom @@ -15,40 +15,53 @@ module libcamera; * * Attributes: * - skipHeader - structs only, and only in core.mojom - * - designate that this struct shall not have a C++ header definition - * generated + * - Do not generate a C++ definition for the structure + * - Any type used in a mojom interface definition must have a corresponding + * definition in a mojo file for the Mojo core to accept it, except for + * types used as map/array members for which a definition is not required + * - This attribute allows defining a symbol for the Mojo core that + * corresponds to a libcamera type without duplicating its definition in the + * generated C++ headers * - skipSerdes - structs only, and only in core.mojom - * - designate that this struct shall not have a (de)serializer generated - * - all fields need a (de)serializer to be defined, either hand-written - * in ipa_data_serializer.h + * - Do not generate a (de)serializer for the structure + * - This attribute instructs the build system that a (de)serializer is + * available for the type and there's no need to generate one + * - All types need a (de)serializer to be defined in order to be transported + * over the IPA protocol. The (de)serializer can be: + * - Manually implemented as a template specialization in + * ipa_data_serializer.cpp in the libcamera sources + * - Generated at build time for types defined in a mojo interfaces * - hasFd - struct fields or empty structs only - * - designate that this field or empty struct contains a FileDescriptor + * - Designate that this field or empty struct contains a FileDescriptor * * Rules: - * - Any struct that is used in a struct definition in mojom must also be - * defined in mojom - * - If the struct has both a definition in a C++ header and a (de)serializer - * in ipa_data_serializer.h, then the struct shall be declared as empty, - * with both the [skipHeader] and [skipSerdes] attributes - * - If the struct only has a definition in a C++ header, but no - * (de)serializer, then the struct definition should have the [skipHeader] - * attribute - * - Nested structures (e.g. FrameBuffer::Plane) cannot be defined in mojom. - * - Avoid them, by defining them in a header in C++ and a (de)serializer in - * ipa_data_serializer.h - * - If a struct is in an array/map inside a struct, then the struct that is - * the member of the array/map does not need a mojom definition if it is - * defined in a C++ header. - * - This can be used to embed nested structures. The C++ double colon is - * replaced with a dot (e.g. FrameBuffer::Plane -> FrameBuffer.Plane) - * - The struct must still be defined in a header in C++ and a (de)serializer - * implemented in ipa_data_serializer.h, as it cannot be defined in mojom + * - If the type is defined in a libcamera C++ header *and* a (de)serializer is + * available then the type shall be declared as empty with both attributes + * associated and specified as: [skipHeader, skipSerdes] + * - Example: [skipHeader, skipSerdes] ControlList {}; + * - If the type is defined in libcamera but no (de)serializer is available + * then the type definition in the core.mojom file should have the + * [skipHeader] attribute only + * - A (de)serializer will be generated for the type + * - If a type definition has [skipHeader], then the header where the type is + * defined must be included in ipa_interface.h + * - Types that are contained in an array/map do not require a mojom definition + * if one exists in libcamera + * - Nested types (e.g. FrameBuffer::Plane) cannot be directly used in mojom + * - If used directly in mojom, the nested type shall be defined in a C++ + * header and a (de)serializer shall be provided + * - The C++ namespace separator :: is replaced with a dot + * - In example, to directly use the FrameBuffer::Plane type: + * - Provide a definition of the Plane type in a C++ header + * - Include the header in ipa_interface.h + * - Provide a (de)serializer implementation ipa_data_serializer.cpp + * - In mojom, reference the type as FrameBuffer.Plane + * - Nested types can be used without an associated C++ definition if used + * as part of an array/map container * - [skipHeader] and [skipSerdes] only work here in core.mojom. - * - If a struct definition has [skipHeader], then the header where the - * struct is defined must be #included in ipa_interface.h * - If a field in a struct has a FileDescriptor, but is not explicitly * defined so in mojom, then the field must be marked with the [hasFd] - * attribute. + * attribute * * \todo Generate documentation from Doxygen comments in .mojom files * \todo Figure out how to keep the skipHeader structs in sync with their