Display VDI 接入指南

概述

显示VDI（Vendor Device Interface）接口是为了方便芯片厂商接入OpenHarmony显示驱动框架模型而提供的接口。 显示VDI接口分为Composer和Buffer部分：

• Composer：负责图层（Layer）合成和显示。
• Buffer：负责申请和释放SurfaceBuffer。

Composer部分

图 1 Display Composer HDI架构

该框架模型内部分为三层，依次为框架层、HDI实现层、和Vendor驱动层。各层基本概念如下：

• 框架层：对接HDI实现层的控制、图层的显示和合成，管理显示模块各个硬件设备等功能。
• HDI实现层：实现OHOS（OpenHarmony Operation System）Composer HDI接口。
• Vendor驱动层：屏蔽底层芯片和OS（Operation System）差异，支持多平台适配。

Buffer部分

图 2 Display Buffer HDI架构

该框架模型内部分为三层，依次为框架层、HDI实现层、和Vendor驱动层。各层基本概念如下：

• 框架层：对接HDI实现层的控制、图形buffer的申请和释放。
• HDI实现层：实现OHOS（OpenHarmony Operation System）Buffer HDI接口。
• Vendor驱动层：屏蔽底层芯片和OS（Operation System）差异，支持多平台适配。

开发指导

Composer部分

接口说明

注：以下接口列举的为VDI接口，接口声明见文件/drivers/peripheral/display/composer/hdi_service/include/idisplay_composer_vdi.h，获取路径为：https://gitee.com/openharmony/drivers_peripheral/tree/master/display/composer。

• idisplay_composer_vdi.h

开发步骤

下面以rk3568为例说明，Composer接入VDI开发过程主要包含以下步骤：

1. 实现Composer VDI接口

芯片厂商应实现idisplay_composer_vdi.h中定义的接口，接口定义如下：

  class DisplayComposerVdiImpl : public IDisplayComposerVdi {
  public:
      DisplayComposerVdiImpl();
      virtual ~DisplayComposerVdiImpl();
      virtual int32_t RegHotPlugCallback(HotPlugCallback cb, void* data) override;
      virtual int32_t GetDisplayCapability(uint32_t devId, DisplayCapability& info) override;
      virtual int32_t GetDisplaySupportedModes(uint32_t devId, std::vector<DisplayModeInfo>& modes) override;
      virtual int32_t GetDisplayMode(uint32_t devId, uint32_t& modeId) override;
      virtual int32_t SetDisplayMode(uint32_t devId, uint32_t modeId) override;
      virtual int32_t GetDisplayPowerStatus(uint32_t devId, DispPowerStatus& status) override;
      virtual int32_t SetDisplayPowerStatus(uint32_t devId, DispPowerStatus status) override;
      virtual int32_t GetDisplayBacklight(uint32_t devId, uint32_t& level) override;
      virtual int32_t SetDisplayBacklight(uint32_t devId, uint32_t level) override;
      virtual int32_t GetDisplayProperty(uint32_t devId, uint32_t id, uint64_t& value) override;
      virtual int32_t GetDisplayCompChange(uint32_t devId, std::vector<uint32_t>& layers,
          std::vector<int32_t>& types) override;
      virtual int32_t SetDisplayClientCrop(uint32_t devId, const IRect& rect) override;
      virtual int32_t SetDisplayClientBuffer(uint32_t devId, const BufferHandle& buffer, int32_t fence) override;
      virtual int32_t SetDisplayClientDamage(uint32_t devId, std::vector<IRect>& rects) override;
      virtual int32_t SetDisplayVsyncEnabled(uint32_t devId, bool enabled) override;
      virtual int32_t RegDisplayVBlankCallback(uint32_t devId, VBlankCallback cb, void* data) override;
      virtual int32_t GetDisplayReleaseFence(uint32_t devId, std::vector<uint32_t>& layers,
          std::vector<int32_t>& fences) override;
      virtual int32_t CreateVirtualDisplay(uint32_t width, uint32_t height, int32_t& format, uint32_t& devId) override;
      virtual int32_t DestroyVirtualDisplay(uint32_t devId) override;
      virtual int32_t SetVirtualDisplayBuffer(uint32_t devId, const BufferHandle& buffer, const int32_t fence) override;
      virtual int32_t SetDisplayProperty(uint32_t devId, uint32_t id, uint64_t value) override;
      virtual int32_t Commit(uint32_t devId, int32_t& fence) override;
      virtual int32_t CreateLayer(uint32_t devId, const LayerInfo& layerInfo, uint32_t& layerId) override;
      virtual int32_t DestroyLayer(uint32_t devId, uint32_t layerId) override;
      virtual int32_t PrepareDisplayLayers(uint32_t devId, bool& needFlushFb) override;
      virtual int32_t SetLayerAlpha(uint32_t devId, uint32_t layerId, const LayerAlpha& alpha) override;
      virtual int32_t SetLayerRegion(uint32_t devId, uint32_t layerId, const IRect& rect) override;
      virtual int32_t SetLayerCrop(uint32_t devId, uint32_t layerId, const IRect& rect) override;
      virtual int32_t SetLayerZorder(uint32_t devId, uint32_t layerId, uint32_t zorder) override;
      virtual int32_t SetLayerPreMulti(uint32_t devId, uint32_t layerId, bool preMul) override;
      virtual int32_t SetLayerTransformMode(uint32_t devId, uint32_t layerId, TransformType type) override;
      virtual int32_t SetLayerDirtyRegion(uint32_t devId, uint32_t layerId, const std::vector<IRect>& rects) override;
      virtual int32_t SetLayerVisibleRegion(uint32_t devId, uint32_t layerId, std::vector<IRect>& rects) override;
      virtual int32_t SetLayerBuffer(uint32_t devId, uint32_t layerId,
          const BufferHandle& buffer, int32_t fence) override;
      virtual int32_t SetLayerCompositionType(uint32_t devId, uint32_t layerId, CompositionType type) override;
      virtual int32_t SetLayerBlendType(uint32_t devId, uint32_t layerId, BlendType type) override;
      virtual int32_t SetLayerMaskInfo(uint32_t devId, uint32_t layerId, const MaskInfo maskInfo) override;
      virtual int32_t SetLayerColor(uint32_t devId, uint32_t layerId, const LayerColor& layerColor) override;
  };
  using CreateComposerVdiFunc = IDisplayComposerVdi* (*)();
  using DestroyComposerVdiFunc = void (*)(IDisplayComposerVdi* vdi);
  extern "C" IDisplayComposerVdi* CreateComposerVdi();
  extern "C" void DestroyComposerVdi(IDisplayComposerVdi* vdi);

2. 编译共享库

实现上述接口后，编译一个名为libdisplay_composer_vdi_impl.z.so的共享库。参考如下编译，BUILD.gn文件见device/soc/rockchip/rk3568/hardware/display/BUILD.gn，获取路径为：https://gitee.com/openharmony/device_soc_rockchip/blob/master/rk3568/hardware/display/BUILD.gn。

  ohos_shared_library("libdisplay_composer_vdi_impl") {
    sources = [ "src/display_device/display_composer_vdi_impl.cpp" ]

    include_dirs = [
      "src/display_device",
      "${root_path}/drivers/peripheral/display/utils/include",
      "${root_path}/drivers/interface/display/composer",
      "${root_path}/drivers/peripheral/display/composer/hdi_service/include",
      "${root_path}/drivers/interface/display/composer/hdifd_parcelable",
    ]

    deps = [ ":display_composer_vendor" ]

    external_deps = [
      "c_utils:utils",
      "drivers_interface_display:display_composer_idl_headers",
      "graphic_chipsetsdk:buffer_handle",
      "hilog:libhilog",
      "ipc:ipc_single",
    ]

    install_enable = true
    install_images = [ chipset_base_dir ]
    subsystem_name = "hdf"
    part_name = "rockchip_products"
  }

BUILD.gn文件编写好后，可以在项目的根目录执行如下命令进行编译：

  ./build.sh -p rk3568 -T display_composer_model

执行完成后，即可在目录out/rk3568/hdf/rockchip_products中找到名为libdisplay_composer_vdi_impl.z.so的共享库。

开发实例

OpenHarmony中有一个默认VDI实现，芯片厂商可参考此实现。见drivers/peripheral/display/composer/vdi_base，获取路径为：https://gitee.com/openharmony/drivers_peripheral/tree/master/display/composer/vdi_base。

Buffer部分

接口说明

注：以下接口列举的为VDI接口，接口声明见文件/drivers/peripheral/display/buffer/hdi_service/include/idisplay_buffer_vdi.h，获取路径为：https://gitee.com/openharmony/drivers_peripheral/tree/master/display/buffer。

• idisplay_composer_vdi.h

开发步骤

下面以rk3568为例说明，Buffer接入VDI开发过程主要包含以下步骤：

1. 实现Buffer VDI接口

芯片厂商应实现idisplay_buffer_vdi.h中定义的接口，接口定义如下：

  class DisplayBufferVdiImpl : public IDisplayBufferVdi {
  public:
      DisplayBufferVdiImpl();
      virtual ~DisplayBufferVdiImpl();

      virtual int32_t AllocMem(const AllocInfo& info, BufferHandle*& handle) const override;
      virtual void FreeMem(const BufferHandle& handle) const override;
      virtual void *Mmap(const BufferHandle& handle) const override;
      virtual int32_t Unmap(const BufferHandle& handle) const override;
      virtual int32_t FlushCache(const BufferHandle& handle) const override;
      virtual int32_t InvalidateCache(const BufferHandle& handle) const override;
      virtual int32_t IsSupportedAlloc(const std::vector<VerifyAllocInfo>& infos,
          std::vector<bool>& supporteds) const override;
      virtual int32_t RegisterBuffer(const BufferHandle& handle) override;
      virtual int32_t SetMetadata(const BufferHandle& handle, uint32_t key, const std::vector<uint8_t>& value) override;
      virtual int32_t GetMetadata(const BufferHandle& handle, uint32_t key, std::vector<uint8_t>& value) override;
      virtual int32_t ListMetadataKeys(const BufferHandle& handle, std::vector<uint32_t>& keys) override;
      virtual int32_t EraseMetadataKey(const BufferHandle& handle, uint32_t key) override;
  };
  using CreateDisplayBufferVdiFunc = IDisplayBufferVdi* (*)();
  using DestroyDisplayBufferVdiFunc = void (*)(IDisplayBufferVdi* vdi);
  extern "C" IDisplayBufferVdi* CreateDisplayBufferVdi();
  extern "C" void DestroyDisplayBufferVdi(IDisplayBufferVdi* vdi);

2. 编译共享库

实现上述接口后，编译一个名为libdisplay_buffer_vdi_impl.z.so的共享库。参考如下编译，BUILD.gn文件见device/soc/rockchip/rk3568/hardware/display/BUILD.gn，获取路径为：https://gitee.com/openharmony/device_soc_rockchip/blob/master/rk3568/hardware/display/BUILD.gn。

  ohos_shared_library("libdisplay_buffer_vdi_impl") {
    sources = [ "src/display_gralloc/display_buffer_vdi_impl.cpp" ]

    public_configs = [ ":libdisplay_buffer_vdi_impl_config" ]

    include_dirs = [
      "./src/display_gralloc",
      "${root_path}/drivers/peripheral/base",
      "${root_path}/drivers/interface/display/composer/hdifd_parcelable",
      "${root_path}/drivers/interface/display/buffer",
      "${root_path}/drivers/peripheral/display/utils/include",
      "${root_path}/drivers/peripheral/display/buffer/hdi_service/include",
    ]

    output_name = "libdisplay_buffer_vdi_impl"
    cflags = [
      "-DGRALLOC_GBM_SUPPORT",
      "-Wno-macro-redefined",
    ]
    deps = [ ":libdisplay_buffer_vendor" ]

    external_deps = [
      "c_utils:utils",
      "drivers_interface_display:display_buffer_idl_headers",
      "drivers_interface_display:display_composer_idl_headers",
      "hdf_core:libhdf_utils",
      "hilog:libhilog",
      "ipc:ipc_single",
    ]

    install_enable = true
    install_images = [ chipset_base_dir ]
    innerapi_tags = [ "passthrough" ]
    subsystem_name = "hdf"
    part_name = "rockchip_products"
  }

BUILD.gn文件编写好后，可以在项目的根目录执行如下命令进行编译：

  ./build.sh -p rk3568 -T display_buffer_model

执行完成后，即可在目录out/rk3568/hdf/rockchip_products中找到名为libdisplay_buffer_vdi_impl.z.so的共享库。

开发实例

OpenHarmony中有一个默认VDI实现，芯片厂商可参考此实现。见drivers/peripheral/display/buffer/vdi_base，获取路径为：https://gitee.com/openharmony/drivers_peripheral/tree/master/display/buffer/vdi_base。