CSI-D IMX728 Camera Count Limit and CSI-AB Link Mapping on DRIVE Thor

Autonomous Vehicles DRIVE AGX Thor DRIVE AGX Thor General
1

We are evaluating cameras on DRIVE Thor with DriveOS 7.0.3 using nvsipl_camera. We would like to confirm whether the following behaviors are expected when using a supported camera configuration.

Environment

  • Platform: DRIVE Thor

  • OS: DriveOS 7.0.3

  • Tool: nvsipl_camera

  • Officially supported camera: Smartlead BF8S103G-100-00

  • Camera used in our evaluation: Smartlead BF8S103G-100-01

Note on Camera Configuration

We understand that the camera used in our evaluation is not exactly the same as the officially supported model. Even so, our questions below are intended to confirm the expected behavior for the supported camera configuration.

1. IMX728 Camera Count on CSI-D

When three or more IMX728 cameras are connected to CSI-D, we encounter an error in nvsipl_camera.

Example command:


./nvsipl_camera \

--platform-config "R0SIM728S3RU2120NB2_5Des_CPHY_x4" \

--link-enable-masks "0x0000 0x00 0x1111 0x0000 0x0000" \

--showfps -d 1

Observed behavior:

  • Video capture works correctly when up to two IMX728 cameras are connected to CSI-D.

  • The same IMX728 cameras can operate successfully with four cameras on other CSI ports such as CSI-GH under comparable conditions.

Based on this behavior, our understanding is that CSI-D may have a port-specific limitation related to bandwidth or the number of supported cameras.

2. link-0 / link-1 Behavior on CSI-AB

We also observed successful video capture when IMX728 cameras are connected to all four CSI-AB links (link-0 through link-3).

However, in the DRIVE AGX Thor Mechanical and Installation Guide, Table 3.17, “Camera Connector to Thor CSI Mapping,” CSI-AB link-0 and link-1 appear to be marked as “Not Connected.”

Reference:

Questions

  1. For IMX728, does CSI-D have any inherent limit on the number of supported cameras or the available bandwidth?

  2. According to the official specification, are CSI-AB link-0 and link-1 intended to be usable?

Any clarification on the intended behavior and specification would be greatly appreciated.

5

Dear @Natsuha_Shishido ,
CSI-D is 2 lane port, From my understanding only 2 IMX728 cameras can work. I will check internally and update you.
CSI-AB port can work with 4 IMX728 cameras. Let me check if it is documentation issue.

7

CSI-D only has 2 CSI lanes. Therefore, the total bandwidth is half of CSI-AB which has 4 CSI lanes. Therefore, if you run multiple high resolution sensors (ex IMX728) on CSI-D, it is likely the total sensor output exceeds the CSI bandwidth and streaming could fail. That is why the streaming worked for 2x IMX728 but not 3x or more IMX728. But on CSI-AB, you can stream with 4x IMX728 without issues

9

Dear @SivaRamaKrishnaNV
Thank you for providing the information

  1. Official documentation for CSI-D lane count and bandwidth

    Is there an official document that states CSI-D has a 2-lane configuration, unlike the other ports, and that also describes the concrete bandwidth of CSI-D?

    If so, could you please share the document name?

  2. Whether CSI-AB link-0 / link-1 are officially usable in the specification

    You mentioned that CSI-AB can work with 4x IMX728 cameras.

    However, in the DRIVE AGX Thor Mechanical and Installation Guide, Table 3.17, “Camera Connector to Thor CSI Mapping,” CSI-AB link-0 and link-1 appear to be marked as “Not Connected.”

    Are you still checking this point internally?

10

Dear @Natsuha_Shishido ,
I filed documentation bug to fix this info..