RK测试显示输出时要把系统其他的显示关掉：service lightdm stop，因为drm只能允许一个显示输出程序。

libdrm-modetest原理及图显系统验证方法

https://cloud.tencent.com/developer/article/1855136

tools:drm-kms调试手段[modetest]

https://blog.csdn.net/u012839187/article/details/103507833?utm_medium=distribute.pc_relevant.none-task-blog-2%7Edefault%7EOPENSEARCH%7Edefault-3.base&depth_1-utm_source=distribute.pc_relevant.none-task-blog-2%7Edefault%7EOPENSEARCH%7Edefault-3.base