ISP IPC Module Framework Description and Interface Specification

ID: RK-KF-YF-519

Release Version: V1.0.0

Date: 2020-06-19

Security Level: □Top-Secret □Secret □Internal ■Public

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Preface

Overview

This document aims to describe the role of the RkAiq (Rk Auto Image Quality) module, the overall workflow, and the related API interfaces. It is mainly intended to assist engineers developing ISP functions using the RkAiq module.

Product Versions

Chip Name	Kernel Version
RV1126/RV1109	Linux 4.19

Intended Audience

This document (guide) is mainly applicable to the following engineers:

ISP module software development engineers

System integration software development engineers

Chip System Support Status

Chip Name	BuildRoot	Debian	Yocto	Android
RV1126	Y	N	N	N
RV1109	Y	N	N	N

Revision History

Version	Author	Date	Description
V1.0.0	Qiu En	2020-06-19	Initial version

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Table of Contents

[TOC]

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Framework Overview

Overview

This module mainly implements the protocol specification for communication between the ispclient application and the ispserver process, as well as the specification for inter-process communication interfaces. Clients use the interface files we provide to interact between the client application and the ispserver process. ispserver mainly depends on the rkaiq library and interacts with isp through the rkaiq library. ispclient does not directly interact with the rkaiq library.

Software Architecture Diagram

Figure 1-1 ISP20 IPC Module Framework Diagram

The ISP20 IPC module framework diagram is shown in Figure 1-1. The module is designed using a layered model.

• ISP uAPI layer: mainly responsible for calling the interfaces provided by the aiq library.
• Protocol layer: the inter-process communication protocol, using a JSON protocol structure.
• IPC layer: mainly provides basic interfaces for inter-process communication, mainly using dbus and shared memory.
• Interface layer: the final interfaces provided to clients; protocol encapsulation is transparent to the client.
• Application layer: interface calls at the application layer.

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Interface Specification

Interface Layer Specification

Interfaces provided to the server and client.

Server:

[Interface Specification]

uAPI interface name + _ipc + (void *args)
void* args: pointer to the shared memory structure. args is the structure of interface parameters, defined in the protocol layer section.

[Interface Path]

$project/isp2-ipc/interface/

[Interface Description]

Since the interface functions correspond to the uAPI interfaces of the rkaiq library, refer to the functional description section of Rockchip_Developer_Guide_ISP20_RkAiq_CN.md for details on each interface. ==Note: When compiling the server, ensure linking against the librkaiq.so library.==

Client:

The implementation of the uAPI .h file interfaces. The client can work without depending on the rkaiq library. It calls the server interface via dbus (uAPI interface name + _ipc + (void *args)), which then calls the aiq library. Header file path: $sysroot/usr/include/rkaiq/uApi directory. ==Note: When compiling the client, ensure linking against ispclient.so.==

Protocol Layer Specification

Since the IPC layer communication mechanism is based on shared memory and DBUS, shared memory is mainly used to transmit interface parameter data. dbus is mainly used to synchronize shared memory, allowing the client to notify the server to synchronize shared memory.

[Protocol Specification]

   typedef struct uAPI interface name {
     rk_aiq_sys_ctx_t* sys_ctx;
     Parameter 2;
     ....
     Parameter N;
     xCamReturn returnvalue;
   }

• The structure name uses the interface name, for unified handling and code simplification.
• The structure fields represent each parameter of the interface.
• The returnvalue field represents the return value of each interface.
• The structure data is stored in shared memory and synchronized via dbus. The dbus protocol is transmitted based on json.
• The json structure mainly informs the other party of the interface name and shared memory id.

[Protocol Path]

$project/isp2-ipc/protocol/

One protocol file corresponds to one header file of uAPI, and each structure corresponds to the parameters of the corresponding interface.

[Protocol Description]

The client communicates with the server via the protocol; the protocol is included in ispclient when used by the client. Refer to Rockchip_Developer_Guide_ISP20_RkAiq_CN.md for the meaning of each protocol field.

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DBSERVER Mode Adaptation

The dbserver mode mainly uses a database approach for inter-process communication. The client writes ISP configuration data to the database, then broadcasts a message to ispserver via dbus. After receiving the message, ispserver calls the aiq interface to update the configuration. To enable this feature, turn on the BR2_PACKAGE_DBSERVER configuration in buildroot/config/xxx.config.h.

Source Code Structure

isp2-ipc
├── client*******************************Client library implementation
│   ├── CMakeLists.txt
│   ├── dbusconfig***********************dbus configuration file
│   └── impl*****************************Client uAPI interface implementation
├── CMakeLists.txt
├── common*******************************Common directory
├── demo*********************************Client test demo
├── interface****************************Server interface definitions
├── libs*********************************aiq library directory
│   └── librkaiq.so
├── LICENSE
├── protocol*****************************Protocol definition directory
└── server*******************************Server implementation
    ├── impl*****************************Server interface implementation, mainly implements interface interfaces
    └── main.c***************************Server main program interface

To obtain this code, add BR2_PACKAGE_ISP2_IPC=y to buildroot/config/xxxconfig.h. After compilation, the server code generates the ispserver binary file.

A Acronyms

Abbreviation	Full Name
isp2-ipc	ISP2.0 Interprocess Communication
RkAiq	Rockchip Automatical Image Quality
ISP	Image Signal Process