1. 概述
显示是非常重要的一个模块，人机交互的桥梁。那么SA8155 Hypervisor显示是如何处理的呢。对处理流程非常的好奇O(∩_∩)O哈哈~。
- 数据流(buffer)，如何刷屏
- 同步机制(Vsync)
- 帧率控制
TODO文章来源：https://uudwc.com/A/dPek0
2.OpenWFD
有点复杂，本文不介绍，标准基础的技术，需要专业的人去磨。如下贴两张图。
图1
图2
3. 显示框架
3.1 显示框架如下图
本人理解绘制
每个WFD Client连接一个显示输出：
eQDIDisplayID : This is the QDI display ID associated with each port.
Should be of type QDI_Display_IDType
QDI_DISPLAY_NONE = 0
QDI_DISPLAY_PRIMARY = 1
QDI_DISPLAY_SECONDARY = 2
QDI_DISPLAY_THIRD = 3
QDI_DISPLAY_EXTERNAL = 4
QDI_DISPLAY_EXTERNAL2 = 5
QDI_DISPLAY_EXTERNAL3 = 6
QDI_DISPLAY_FRAMEBUFFER = 7 <WFDClient
ID = '0x7817'
eWFDClientType = '0x7'>
<WFDPort ID='1'>
<PortAttribs
eQDIDisplayID = '3'
uDisplayNode = '0'
ePortType = '0x7660'
eZOrderBase = '0'
></PortAttribs>
<WFDPipeline
eQDILayerID = '17'
eZOrder = '0'
></WFDPipeline>
</WFDPort>
</WFDClient>3.2 Graphics Hypervisor 架构：
4. QNX MDSS(MultiMedia Display Sub System)及WFD相关
核心代码路基：qnx_ap/AMSS/multimedia/display
TODO
5. Bridge Driver/ 配置部分(重点)
常规座舱设计：
开发板设计：
核心代码路径：qnx_ap/boards/display
5.1 目录架构：
├── adp_star_sda8155
│ ├── config
│ │ ├── graphics_ADP_STAR.conf
│ │ ├── graphics_ADP_STAR_FDN.conf
│ │ ├── graphics_ADP_STAR_GVM.conf
│ │ ├── Makefile
│ │ ├── qcdisplaycfg_ADP_STAR_FDN.xml
│ │ ├── qcdisplaycfg_ADP_STAR_LA_MULTI_DISP.xml //WFDClient各个显示输出配置
│ │ └── qcdisplaycfg_ADP_STAR.xml
│ └── Makefile
├── common
│ ├── bridge_chip //涉及高可用框架
│ │ ├── client //客户端(API)
│ │ ├── drv //驱动/资源管理器
│ │ ├── Makefile
│ │ ├── plugins //串行解串芯片相关
│ │ └── server //服务端(高可用进程)
│ ├── Makefile
│ └── panels //屏接口配置，以及DSI->DP等转换芯片
│ ├── DANX7625_DP_QC_0
│ ├── DANX7625_DP_QC_1
│ ├── DANX7625_DP_QC_2
│ ├── DANX7625_DP_QC_3
│ ├── DP1_COMMON_QC
│ ├── DP_BOND_COMMON_QC
│ ├── DP_COMMON_MST_QC
│ ├── DP_COMMON_QC
│ ├── DSI_COMMON_QC_0
│ ├── DSI_COMMON_QC_1
│ ├── EDP_COMMON_QC
│ ├── Makefile
│ ├── public
│ ├── SDANX7625x2_DPx2_QC_8155
└── Makefile
Demo板中硬件接口对应的屏驱动文件：
| Display interface | driver for SA8155 Panel(Demo板) |
| DSI-0 | DANX7625_DP_QC_0 |
| DSI-1 | DANX7625_DP_QC_1 |
| DP0 | DP_COMMON_QC |
| DP-MST | DP_COMMON_MST_QC |
| DP1 | N/A |
| eDP | N/A |
TODO
5.2 Bridge Driver(Server/Client)资源管理器
TODO
5.3 转换芯片(DSI->DP)
TODO
5.4 串行解串(Serializer/DeSerializer)
行业两大技术：
- Ti的 PDLINK3
- 美信的 GMSL1/2
PDLINK 代表芯片：DS90UH947--DS90UH948
DS90UH953--DS90UH954
DS90UH941--DS90UH981
GMSL2 代表芯片：Max96737--Max96752
Max96718--Max96717
Max96751--Max96718F
Max96745--Max96768
Max96789--Max96752F/Max9278
├── common
│ │ ├── plugins //串行解串相关
│ │ │ ├── DS90UH981Q_QC_0 //TI PDLINK3 UH981
│ │ │ ├── DS90UH983Q_QC_0 //TI PDLINK3 UH983
│ │ │ └── Makefile
TODO
5.5 qcdisplaycfg配置
5.5.1 WFDClinet配置：
描述
<!-- WFD Configurations : Used to configure WFD driver -->
<WFDConfig>
<!-- Client enumeration :
ID : Defines a unique value that resembles a client. It must have a prefix of 0x78##;
where ## is any unique value for each of the clients.
Exception: Client ID 0x78FF must be used for SCREEN.
eWFDClientType : Defines the Client Type associated with different clients
WFD_CLIENT_TYPE_CLUSTER = 0x1
WFD_CLIENT_TYPE_MONITOR = 0x2
WFD_CLIENT_TYPE_TELLTALE = 0x3
WFD_CLIENT_TYPE_RVC = 0x4
WFD_CLIENT_TYPE_LA_GVM = 0x5
WFD_CLIENT_TYPE_LV_GVM = 0x6
WFD_CLIENT_TYPE_SPLASH = 0x7Port enumeration :
ID : Defines the order in which ports are enumerated
to client. Starts from '0'Port configuration : Define attributes for each enumerated port.
Following attributes to be set
eQDIDisplayID : This is the QDI display ID associated with each port.
Should be of type QDI_Display_IDType
QDI_DISPLAY_NONE = 0
QDI_DISPLAY_PRIMARY = 1
QDI_DISPLAY_SECONDARY = 2
QDI_DISPLAY_THIRD = 3
QDI_DISPLAY_EXTERNAL = 4
QDI_DISPLAY_EXTERNAL2 = 5
QDI_DISPLAY_EXTERNAL3 = 6
QDI_DISPLAY_FRAMEBUFFER = 7
ePortType : This defines the type of the port.
Should be of type WFDPortType
WFD_PORT_TYPE_INTERNAL = 0x7660
WFD_PORT_TYPE_COMPOSITE = 0x7661
WFD_PORT_TYPE_SVIDEO = 0x7662
WFD_PORT_TYPE_COMPONENT_YPbPr = 0x7663
WFD_PORT_TYPE_COMPONENT_RGB = 0x7664
WFD_PORT_TYPE_COMPONENT_RGBHV = 0x7665
WFD_PORT_TYPE_DVI = 0x7666
WFD_PORT_TYPE_HDMI = 0x7667
WFD_PORT_TYPE_DISPLAYPORT = 0x7668
WFD_PORT_TYPE_DSI = 0x766A
eZOrderBase : Starting Z-order for layers assigned to this port for
this clientPipeline configuration : Define attributes for each enumerated pipeline
within a port. Following attributes to be set
eQDILayerID : This is the QDI layer ID associated with each pipeline.
Should be of type QDI_Layer_IDType
QDI_LAYER_ID_OVERLAY1 = 5 - ViG0 (supports YUV content)
QDI_LAYER_ID_OVERLAY2 = 6 - ViG1 (supports YUV content)
QDI_LAYER_ID_OVERLAY3 = 7 - ViG2 (supports YUV content)
QDI_LAYER_ID_OVERLAY4 = 8 - ViG3 (supports YUV content)
QDI_LAYER_ID_OVERLAY5 = 9 - ViG4 (ViG0 REC1)
QDI_LAYER_ID_OVERLAY6 = 10 - ViG5 (ViG1 REC1)
QDI_LAYER_ID_OVERLAY7 = 11 - ViG6 (ViG2 REC1)
QDI_LAYER_ID_OVERLAY8 = 12 - ViG7 (ViG3 REC1)
QDI_LAYER_ID_DMA1 = 14 - DMA0
QDI_LAYER_ID_DMA2 = 15 - DMA1
QDI_LAYER_ID_DMA3 = 16 - DMA2
QDI_LAYER_ID_DMA4 = 17 - DMA3
QDI_LAYER_ID_DMA5 = 18 - DMA4 (DMA0 REC1)
QDI_LAYER_ID_DMA6 = 19 - DMA5 (DMA1 REC1)
QDI_LAYER_ID_DMA7 = 20 - DMA6 (DMA2 REC1)
QDI_LAYER_ID_DMA8 = 21 - DMA7 (DMA3 REC1)
eZOrder : Defines the Z-order of each pipeline within the port
Should be of type QDI_ZorderType
QDI_ZORDER_0 = 0 - bottom layer
QDI_ZORDER_1 = 1 - stage 1 layer
QDI_ZORDER_2 = 2 - stage 2 layer
QDI_ZORDER_3 = 3 - stage 3 layer
QDI_ZORDER_4 = 4 - stage 4 layer
QDI_ZORDER_5 = 5 - stage 5 layer
QDI_ZORDER_6 = 6 - stage 6 layer
QDI_ZORDER_7 = 7 - stage 7 layer
QDI_ZORDER_8 = 8 - stage 8 layer
QDI_ZORDER_9 = 9 - stage 9 layer
QDI_ZORDER_10 = 10 - top layerRestrictions:
- Each QDI layer ID can be used inside one WFDPipeline tag only
- WFDPipeline tags within one eQDIDisplayID tag must have unique eZOrder.
i.e. Two WFDPipelines cannot have the same eZOrder within the same
eQDIDisplayID
- Pipelines that represent different rectangles of the same physical pipe
must use the same QDI display ID.
i.e. If DMA0 is used on eQDIDisplayID='1' then DMA4 must also be used on
eQDIDisplayID='1', even if the pipelines are assigned to different clients
- RECT1 pipelines cannot be assigned to displays wider than 2048 pixels
-->
参考案例：
<WFDClient
ID = '0x7812' //Client ID，每个显示ID不同(0x7800~0x78FF)
eWFDClientType = '0x3'>//Client Type，倒车RVC还是仪表，还是HMI
<WFDPort ID='1'>//
<PortAttribs
eQDIDisplayID = '1'//显示ID，首屏，副屏等
uDisplayNode = '0'
ePortType = '0x7660'//显示接口类型，DSI/DP/eDP等
eZOrderBase = '10'
></PortAttribs>
<WFDPipeline
eQDILayerID = '8'
eZOrder = '10'
></WFDPipeline>
</WFDPort>
</WFDClient>
5.5.2 显示参数配置
- 分辨率
- 前后肩
- 时钟
- 其他
<Display ID='1'> //显示ID QDI_DISPLAY_PRIMARY 对应 eQDIDisplayID
<!-- Panel Library:
cPanelDriverRoot : Directory where the panel driver library is stored
cPanelName : Name of the panel driver library
--><PanelLibrary //屏驱动
cPanelDriverRoot = '/lib64/'
cPanelName = 'DANX7625_DP_QC_0' //DSI->转DP芯片
></PanelLibrary><PanelVideoTiming//时序配置
ePixelFormatType = '3' //格式
uVisWidth = '1920'
uHsyncFrontPorch = '88'
uHsyncWidth = '44'
uHsyncBackPorch = '148'
uVisHeight = '1080'
uVsyncFrontPorch = '4'
uVsyncWidth = '5'
uVsyncBackPorch = '36'
uPixelFreqInHz = '148500000'
bDEPolarity = '0'
></PanelVideoTiming><DSIConfiguration //DSI配置
cBridgeChipID = 'NATIVE' //是否有BridgeChip(串解器)，没有就是NATIVE
eMapSelect = '0'
uNumOfLanes = '4'// DSI LANE数量
></DSIConfiguration>
</Display>
TODO
6. 高可用机制(重要)
高可用机制是汽车电子软件设计的可靠性、稳定性的可靠保障。汽车电子产品尤其是前装，本着可靠性，稳定性第一原则。
TODO
6.1 异常监控
TODO
6.2 异常定位
TODO
6.3 异常恢复
TODO
6.4 热拔插支持
TODO
7. 总结
综上，对于BSP开发人员来讲，梳理后，感觉不难吧，O(∩_∩)O哈哈~。技术还是那些技术，只不过换了个平台，换了一种实现方式。文章来源地址https://uudwc.com/A/dPek0
