From which register, I can know the camera is online?

My xavier board version is R32.3.1 and the cameras is connected to the board via MIPI. I want to know whether the camera is online or not. Can you point out the register of MIPI to get the status of the camera?

There’s no REG for this. But you can have v4l2-ctl --list-devices to list the devices.

I have list the devices, but the the devices which the camera is not online is also listed.Do the MIPI have the frame count REG when there is data in?

You should check the sensor REG to check if the sensor is present or not.

There is a state that no camera is existed and only csi clock and data is connected with Xavier.
I try to get the value of VI_CSIMUX_STAT_FRAME_0. I try the command ./reg 0x15c144a4 and ./reg 0x15c054a4, and kernel all crashed. (the reg is get from Accessing registers from Linux).How can I get the value of the reg VI_CSIMUX_STAT_FRAME_0?

You can’t access those VI REG with some power gate enable/disable.
Also there’s no any NVCSI/VI/ISP REG able to know if the sensor is online or not.

If there is no input from the data line of csi and we have operation on the /dev/video*,the xavier of version 32.3.1 will crashed. How can I work around it?

Make the input available would be the only solution.