CameraProvider进程-Android12

android12-release
CameraService启动-Android12 看到CameraProviderManager与CameraProvider进程建立联系。这里我们查看一下CameraProvider进程

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1. rc文件android.hardware.camera.provider@2.4-service_64.rc

CameraProvider进程名：vendor.camera-provider-2-4 ，
bin文件：/vendor/bin/hw/android.hardware.camera.provider@2.4-service_64
对应启动入口：hardware/interfaces/camera/provider/2.4/default/service.cpp

hardware/interfaces/camera/provider/2.4/default/android.hardware.camera.provider@2.4-service_64.rc

2. service.cpp#main()启动

• android::ProcessState::initWithDriver("/dev/vndbinder"); kernel底层/dev/vndbinder驱动
• defaultPassthroughServiceImplementation("legacy/0", 6) 直通式Passthrough注册服务给hwservicemanager。（其中使用了#include 类，ICameraProvider类是由HIDL接口定义文件 ICameraProvider.hal 经过hidl-gen编译工具编译生成）

int main()
{
    ALOGI("CameraProvider@2.4 legacy service is starting.");
    // The camera HAL may communicate to other vendor components via
    // /dev/vndbinder
    android::ProcessState::initWithDriver("/dev/vndbinder");

    // b/166675194
    if (property_get_bool("ro.vendor.camera.provider24.disable_mem_init", false)) {
        if (mallopt(M_BIONIC_ZERO_INIT, 0) == 0) {
            // Note - heap initialization is only present on devices with Scudo.
            // Devices with jemalloc don't have heap-init, and thus the mallopt
            // will fail. On these devices, you probably just want to remove the
            // property.
            ALOGE("Disabling heap initialization failed.");
        }
    }

    status_t status;
    if (kLazyService) {
        status = defaultLazyPassthroughServiceImplementation<ICameraProvider>("legacy/0",
                                                                              /*maxThreads*/ 6);
    } else {
        status = defaultPassthroughServiceImplementation<ICameraProvider>("legacy/0",
                                                                          /*maxThreads*/ 6);
    }
    return status;
}
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2.1 ICameraProvider.hal生成CameraProvider.h

可以查看 HIDL实战笔记，相关文件查看上面rc目录等相关文件。HIDL机制本身是跨进程通信，所以Camera Service本身通过HIDL接口获取的对象都会有Bn端和Bp端，分别代表了Binder两端。
hardware/interfaces/camera/provider/2.4/default/CameraProvider_2_4.h
hardware/interfaces/camera/provider/2.4/default/CameraProvider_2_4.cpp

ICameraProvider.hal文件中定义了ICameraProvider接口类，由CameraProvider继承并实现，主要接口如下：

• getCameraDeviceInterface_V3_x: 该方法主要用于Camera Service获取ICameraDevice，通过该对象可以控制Camera 设备的诸如配置数据流、下发request等具体行为。
• setCallback：将Camera Service 实现的ICameraProviderCallback传入Camera Provider，一旦Provider有事件产生时便可以通过该对象通知Camera Service。
  
  

ICameraProviderCallback.hal文件中定义了ICameraProviderCallback回调接口类，该接口由Camera Service 中的CameraProviderManager::ProviderInfo继承并实现，在Camera Service 启动的时候被实例化，通过调用ICameraProvider::setCallback接口注册到Camera Provider中，其主要接口如下：

• cameraDeviceStatusChange：将Camera 设备状态上传至Camera Service，状态由CameraDeviceStatus定义

hardware/interfaces/camera/provider/2.4/ICameraProvider.hal

package android.hardware.camera.provider@2.4;

import ICameraProviderCallback;
import android.hardware.camera.common@1.0::types;
import android.hardware.camera.device@1.0::ICameraDevice;
import android.hardware.camera.device@3.2::ICameraDevice;

interface ICameraProvider {

    setCallback(ICameraProviderCallback callback) generates (Status status);

    getVendorTags() generates (Status status, vec<VendorTagSection> sections);

    getCameraIdList()
            generates (Status status, vec<string> cameraDeviceNames);

    isSetTorchModeSupported() generates (Status status, bool support);

    getCameraDeviceInterface_V1_x(string cameraDeviceName) generates
            (Status status,
             android.hardware.camera.device@1.0::ICameraDevice device);
    getCameraDeviceInterface_V3_x(string cameraDeviceName) generates
            (Status status,
             android.hardware.camera.device@3.2::ICameraDevice device);

};
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hardware/interfaces/camera/provider/2.4/ICameraProviderCallback.hal

package android.hardware.camera.provider@2.4;

import android.hardware.camera.common@1.0::types;

/**
 * Callback functions for a camera provider HAL to use to inform the camera
 * service of changes to the camera subsystem.
 */
interface ICameraProviderCallback {

    cameraDeviceStatusChange(string cameraDeviceName,
            CameraDeviceStatus newStatus);

    torchModeStatusChange(string cameraDeviceName,
            TorchModeStatus newStatus);

};
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2.2 HIDL直通式

ServiceManagement.cpp中openLibs() 调用到CameraProvider_2_4.cpp的HIDL_FETCH_ICameraProvider(const char* name)方法
（HAL 接口定义语言 (AIDL/HIDL) 在 Android 10 中，HIDL 功能已整合到 AIDL 中。此后，HIDL 就被废弃了，并且仅供尚未转换为 AIDL 的子系统使用。）

system/libhidl/transport/include/hidl/LegacySupport.h
system/libhidl/transport/LegacySupport.cpp
system/libhidl/transport/ServiceManagement.cpp
hardware/interfaces/camera/provider/2.4/default/CameraProvider_2_4.cpp

fqName为android.hardware.camera.provider@2.4::ICameraProvider

2.3 CameraProvider初始化模板

template其中IMPL相关文件hardware/interfaces/camera/provider/2.4/default/LegacyCameraProviderImpl_2_4.cpp、hardware/interfaces/camera/provider/2.4/default/ExternalCameraProviderImpl_2_4.cpp

hardware/interfaces/camera/provider/2.4/default/CameraProvider_2_4.h

template<typename IMPL>
struct CameraProvider : public ICameraProvider {
    CameraProvider() : impl() {}
    ~CameraProvider() {}

    // Caller must use this method to check if CameraProvider ctor failed
    bool isInitFailed() { return impl.isInitFailed(); }

    // Methods from ::android::hardware::camera::provider::V2_4::ICameraProvider follow.
    Return<Status> setCallback(const sp<ICameraProviderCallback>& callback) override {
        return impl.setCallback(callback);
    }

    Return<void> getVendorTags(getVendorTags_cb _hidl_cb) override {
        return impl.getVendorTags(_hidl_cb);
    }

    Return<void> getCameraIdList(getCameraIdList_cb _hidl_cb) override {
        return impl.getCameraIdList(_hidl_cb);
    }

    Return<void> isSetTorchModeSupported(isSetTorchModeSupported_cb _hidl_cb) override {
        return impl.isSetTorchModeSupported(_hidl_cb);
    }

    Return<void> getCameraDeviceInterface_V1_x(
            const hidl_string& cameraDeviceName,
            getCameraDeviceInterface_V1_x_cb _hidl_cb) override {
        return impl.getCameraDeviceInterface_V1_x(cameraDeviceName, _hidl_cb);
    }

    Return<void> getCameraDeviceInterface_V3_x(
            const hidl_string& cameraDeviceName,
            getCameraDeviceInterface_V3_x_cb _hidl_cb) override {
        return impl.getCameraDeviceInterface_V3_x(cameraDeviceName, _hidl_cb);
    }

private:
    IMPL impl;
};
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hardware/interfaces/camera/provider/2.4/default/CameraProvider_2_4.cpp

template<typename IMPL>
CameraProvider<IMPL>* getProviderImpl() {
    CameraProvider<IMPL> *provider = new CameraProvider<IMPL>();
    if (provider == nullptr) {
        ALOGE("%s: cannot allocate camera provider!", __FUNCTION__);
        return nullptr;
    }
    if (provider->isInitFailed()) {
        ALOGE("%s: camera provider init failed!", __FUNCTION__);
        delete provider;
        return nullptr;
    }
    return provider;
}
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3. 简要时序图

4. HAL硬件框架

深入理解高通 Camx CHI 架构 - segmentfault
高通CamX关键流程 - 腾讯云
CamX关键流程 - 简书