Orin specific Display Configuration

Update DCB blob for Custom Carrier Boards

Display Control Block (DCB) describes the display outputs and their configurations on a platform. Refer to https://download.nvidia.com/open-gpu-doc/DCB/2/DCB-4.x-Specification.html for more information about DCB.

The DCB blob is stored in platform specific dtsi files in the nvidia,dcb-image property under the display node. AGX Orin’s DCB blob is in the tegra234-dcb-p3701-0000-a02-p3737-0000-a01.dtsi file.

dcb_tool:

DCB blob is made up of hex values, which makes it difficult to decode/edit manually. dcb_tool helps parse DCB blob in dtsi file and also helps modify the values of the fields in the DCB blob. The dcb_tool is packaged in the <top>/Linux_for_Tegra/tools/dcb_tool/ directory.

Refer to the <top>/Linux_for_Tegra/tools/dcb_tool/readme.txt file for more information about the dcb_tool commands and their usage.

Note

To update the DCB blob, users need to reflash the Orin platform.

Changing the Display Function Between DP and HDMI

The Jetson Orin SOM provides DP or HDMI functionality. The pinmux sheet contains the tab for DP and HDMI. Depending on their custom carrier board design, end users should generate the appropriate pinmux files. In addition to pinmux changes, the kernel display dtsi files needs to be included in the carrier board kernel DT files, which contains DCB blob update to change between DP and HDMI Refer to Orin Display Configuration.

VT switching support

The VT switching feature is enabled with or without the desktop GUI. This feature is supported when the monitor is connected to Jetson Orin before and after device bootup.

Enable VT switching as a default option:

Update ``driver`` option in file ``/etc/X11/xorg.conf`` from ``nvidia`` to ``FBDev`` and reboot

Note

  • The procedure above works only when the desktop manager is X11 and not Weston.

  • Here are the Limitations of the FBDev driver:

    • When FBDev driver is specified in the /etc/X11/xorg.conf file, the NVIDIA kernel display drivers are not loaded. This means there is no driver in the OS that controls the display functionality.

    • In this mode, Display is enabled by UEFI driver, and the scan-out frame buffer is passed to the OS which is then used by graphical applications.

    • Since There is no active display driver running in this mode, there are limitation with this approach. few described below.

      • Screen tearing is possible because the frame buffer blit and scan-outs are not controlled.

      • Display does not resume after Suspend/Resume.

      • The Weston apps does not work.

Seamless Display Support

Seamless display is supported from bootloader to kernel handover, but there will be blank display before desktop manager comes up.

Known Limitations

  • Killing the X11 that was launched with NVIDIA Kernel Display driver will not return user to the VT terminal.