这一节主要说说rkmedia vo模块的使用。

rkmedia的vo是对DRM接口的封装，提供给用户更方便的使用，rv1126/rv1109支持两个vo图层。

1、首先先介绍一下DRM的测试命令--modetest，用来确认当前屏幕能够正常点亮。 

modetest -M rockchip  //打印出rk平台的显示层的信息[root@RV1126_RV1109:/userdata]# modetest -M rockchip
Encoders:
id      crtc    type    possible crtcs  possible clones
55      53      DSI     0x00000001      0x00000000Connectors:
id      encoder status          name            size (mm)       modes   encoders
56      55      connected       DSI-1           68x121          1       55modes:name refresh (Hz) hdisp hss hse htot vdisp vss vse vtot)720x1280 60 720 768 776 828 1280 1296 1302 1317 65000 flags: nhsync, nvsync; type: preferred, driverprops:1 EDID:flags: immutable blobblobs:value:2 DPMS:flags: enumenums: On=0 Standby=1 Suspend=2 Off=3value: 05 link-status:flags: enumenums: Good=0 Bad=1value: 06 non-desktop:flags: immutable rangevalues: 0 1value: 043 brightness:flags: rangevalues: 0 100value: 5044 contrast:flags: rangevalues: 0 100value: 5047 saturation:flags: rangevalues: 0 100value: 5048 hue:flags: rangevalues: 0 100value: 50CRTCs:
id      fb      pos     size
53      0       (0,0)   (720x1280)720x1280 60 720 768 776 828 1280 1296 1302 1317 65000 flags: nhsync, nvsync; type: preferred, driverprops:38 left margin:flags: rangevalues: 0 100value: 10039 right margin:flags: rangevalues: 0 100value: 10040 top margin:flags: rangevalues: 0 100value: 10041 bottom margin:flags: rangevalues: 0 100value: 10051 FEATURE:flags: immutable bitmaskvalues: afbdc=0x1value: 0Planes:
id      crtc    fb      CRTC x,y        x,y     gamma size      possible crtcs
52      0       0       0,0             0,0     0               0x00000001formats: XR24 AR24 XB24 AB24 RG24 BG24 RG16 BG16props:8 type:flags: immutable enumenums: Overlay=0 Primary=1 Cursor=2value: 150 FEATURE:flags: immutable bitmaskvalues: scale=0x1 alpha=0x2 hdr2sdr=0x4 sdr2hdr=0x8 afbdc=0x10value: 2
54      0       0       0,0             0,0     0               0x00000001formats: XR24 AR24 XB24 AB24 RG24 BG24 RG16 BG16 NV12 NV16 NV24props:8 type:flags: immutable enumenums: Overlay=0 Primary=1 Cursor=2value: 050 FEATURE:flags: immutable bitmaskvalues: scale=0x1 alpha=0x2 hdr2sdr=0x4 sdr2hdr=0x8 afbdc=0x10value: 3Frame buffers:
id      size    pitch

modetest -M rockchip -s 56:720x1280 //正常情况下 在对应屏幕会有彩色条纹显示-s指定的56 是connectors id号，720x1280 是显示分辨率。rv1126 evb板配上的是此分辨率的屏，所以在正常情况下，屏幕会点亮并出现彩色条纹

 效果图：

2、rkmedia的vo图层有两个：

VO_PLANE_OVERLAY ：支持RGB888,ARGB8888,RGB565,422,420(nv12),444,

VO_PLANE_PRIMARY ：支持RGB888,ARGB8888,RGB565

如果需要叠加ui界面，一般情况是放在primary层，overlay层用来显示视频

  // VO[0] for primary planestVoAttr.pcDevNode = "/dev/dri/card0";stVoAttr.emPlaneType = VO_PLANE_PRIMARY;stVoAttr.enImgType = IMAGE_TYPE_RGB888;stVoAttr.u16Zpos = 0;stVoAttr.stDispRect.s32X = 0;stVoAttr.stDispRect.s32Y = 0;stVoAttr.stDispRect.u32Width = disp_width;stVoAttr.stDispRect.u32Height = disp_height;ret = RK_MPI_VO_CreateChn(0, &stVoAttr);if (ret) {printf("Create vo[0] failed! ret=%d\n", ret);return -1;}// VO[0] for overlay planestVoAttr.pcDevNode = "/dev/dri/card0";stVoAttr.emPlaneType = VO_PLANE_OVERLAY;stVoAttr.enImgType = IMAGE_TYPE_NV12;stVoAttr.u16Zpos = 0;stVoAttr.stDispRect.s32X = 0;stVoAttr.stDispRect.s32Y = 0;stVoAttr.stDispRect.u32Width = disp_width;stVoAttr.stDispRect.u32Height = disp_height;ret = RK_MPI_VO_CreateChn(0, &stVoAttr);if (ret) {printf("Create vo[0] failed! ret=%d\n", ret);return -1;}

如果设置双层同时显示，记得要配置zpos。zpos的值为0或1,1在上层 0在下层。 

查看屏幕信息：

cat /sys/kernel/debug/dri/0/summary

VOP [ffb00000.vop]: ACTIVEConnector: DSIbus_format[100a]: RGB888_1X24overlay_mode[0] output_mode[0] color_space[0]Display mode: 720x1280p60clk[65000] real_clk[65000] type[48] flag[a]H: 720 768 776 828V: 1280 1296 1302 1317win0-0: DISABLEDwin2-0: DISABLEDpost: sdr2hdr[0] hdr2sdr[0]pre : sdr2hdr[0]post CSC: r2y[0] y2r[0] CSC mode[1]

vo部分遇到的问题不多，只要可以用modetest点亮屏幕，用rkmedia也可以点亮。

rkmedia提供测试vo demo： rkmedia_vo_display_test

暂时关于VO部分写这么多，有新的建议后续加上来