# V4L2 Buffer Errors & Initialization Bug with Multi-Camera Sync on Jetson **URL:** \ **Category:** Jetson Orin NX\ **Tags:** camera\ **Created:** [August 25, 2025, 5:48pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123 "2025-08-25T17:48:29Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![gianlucacapezzuto](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@gianlucacapezzuto](https://forums.developer.nvidia.com/u/gianlucacapezzuto)\ **Post date:** [August 25, 2025, 5:48pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/1 "2025-08-25T17:48:29Z")
Hello everyone, We are facing a persistent issue with a multi-camera setup on a Jetson platform and are hoping to get some insights from the community, as we suspect the problem might be at a lower level than the camera-specific ROS drivers. Our Setup: - **Platform** : Aetina Orin NX 16GB, AIB-SN41-1-A1 - **JetPack / L4T** : 5.1.2 (R35.4.1) - **Cameras** : 2x e-con Systems e-CAM25\_CUONX (AR0234 sensor) - **Software** : ROS1 Noetic - **Goal** : Synchronize two cameras using an external hardware trigger and timestamps in ROS. **The Core Problem: V4L2 Buffer Errors** When we run our ROS nodes to capture and synchronize the two camera streams, one of the streams will inevitably fail after a short period. We have been in contact with the camera manufacturer, and they’ve suggested this is a `V4L2 buffer dequeue error`. We have verified our trigger signal is clean and stable. **Key Finding: A Reproducible Initialization Order Bug** While debugging, we discovered a **strict initialization order dependency**. We suspect this may be related to how entity priority is handled in the NVCSI controller. - **Working Order** : If we initialize Camera A **first** , and then Camera B **second** , both streams work perfectly. - **Failing Order** : If we initialize Camera B **first** , then Camera A fails to start. **Summary & Question for the Community** This initialization bug makes us believe the root cause isn’t just in the ROS application layer but potentially deeper in the stack. The fact that the order in which we access nodes determines if a device works or not points towards a potential resource conflict, a race condition, or an issue in how the V4L2 kernel drivers or the underlying NVIDIA Argus stack handle multiple CSI devices being activated in quick succession. 1. Has anyone in the community encountered similar V4L2 buffer errors or strange initialization dependencies with multi-camera setups on Jetson platforms? 2. Could this behavior be related to the NVIDIA V4L2 drivers or the Argus daemon’s management of the CSI ports? 3. Are there any recommended debugging steps at the `dmesg` or kernel level that could help us trace why one camera fails to initialize based on this sequence? Any advice or insights would be greatly appreciated! [2025-08-22\_20-56-56\_dmesg.log](https://forums.developer.nvidia.com/uploads/short-url/cQ6v8sjQK2RXn2FiUjsgrwdd9Zm.log) (176.7 KB) ---
**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\ **Post date:** [August 26, 2025, 5:32am UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/3 "2025-08-26T05:32:09Z")
1. Can these sensor running in unsync mode? Try if unsync mode. 2. Set the timeout to infinite by modify the capture timeout to -1 in vi5\_fops.c ---
**Author:** ![gianlucacapezzuto](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@gianlucacapezzuto](https://forums.developer.nvidia.com/u/gianlucacapezzuto)\ **Post date:** [August 26, 2025, 2:21pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/4 "2025-08-26T14:21:23Z")
Thank you for the response. 1. We tested the cameras in freerun mode, and they work without any buffer errors. However, our application requires precise multi-camera synchronization, which is why we must use the external hardware trigger. 2. We already tested this modification during our initial troubleshooting, and it did not resolve the buffer errors. Let me know if you need more information. ---
**Author:** ![enrique.ramirez](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/enrique.ramirez/32/273049_2.png) [@enrique.ramirez](https://forums.developer.nvidia.com/u/enrique.ramirez)\ **Post date:** [August 26, 2025, 2:28pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/5 "2025-08-26T14:28:54Z")
Hi, As a suggestion, have you tried reproducing the problem using v4l2-ctl? In this way we can make sure that the problem is not related to your application. I could try the following command: ```auto v4l2-ctl -d /dev/videoX --set-ctrl bypass_mode=0 --stream-mmap --stream-count=500 ``` Enrique Ramirez Embedded SW Engineer at RidgeRun Contact us: [support@ridgerun.com](mailto:support@ridgerun.com) Developers wiki: [https://developer.ridgerun.com](https://developer.ridgerun.com/) Website: [www.ridgerun.com](http://www.ridgerun.com/) ---
**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\ **Post date:** [August 26, 2025, 4:10pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/6 "2025-08-26T16:10:18Z")
> [@gianlucacapezzuto](#): > > We already tested this modification during our initial troubleshooting, and it did not resolve the buffer errors. What’s the error? ---
**Author:** ![gianlucacapezzuto](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@gianlucacapezzuto](https://forums.developer.nvidia.com/u/gianlucacapezzuto)\ **Post date:** [August 26, 2025, 6:25pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/7 "2025-08-26T18:25:40Z")
Thank you for the helpful suggestion. I tested both initialization orders using `v4l2-ctl` while the cameras were running in external\_trigger mode. Both cameras streamed without any errors, regardless of which one was started first. For context, our application’s camera handling logic is based on the package e-con Systems recommended: `rqt_cam` ([link](https://github.com/econsystems/rqt_cam)), specifically the logic within `camera.cpp` ([link](https://github.com/econsystems/rqt_cam/blob/master/source/ecam_v4l2/src/camera.cpp)). ---
**Author:** ![gianlucacapezzuto](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@gianlucacapezzuto](https://forums.developer.nvidia.com/u/gianlucacapezzuto)\ **Post date:** [August 26, 2025, 6:27pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/8 "2025-08-26T18:27:47Z")
These are the specific V4L2 buffer flags when the error occurs: `V4L2_BUF_FLAG_ERROR` and `V4L2_BUF_FLAG_MAPPED`. I also captured buffer index and another details: `(buffer index: 0, bytesused: 1843200, sequence: 0)` ---
**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\ **Post date:** [August 27, 2025, 1:53am UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/9 "2025-08-27T01:53:23Z")
Any kernel error like capture timeout? ---
**Author:** ![gianlucacapezzuto](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@gianlucacapezzuto](https://forums.developer.nvidia.com/u/gianlucacapezzuto)\ **Post date:** [August 27, 2025, 3:06pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/11 "2025-08-27T15:06:02Z")
Hi, Here are the errors that appear when the stream fails. The full log is available in the first post of this thread for reference. `[Fri Aug 22 20:54:24 2025] tegra-camrtc-capture-vi tegra-capture-vi: uncorr_err: request timed out after 2500 ms` `[Fri Aug 22 20:54:24 2025] tegra-camrtc-capture-vi tegra-capture-vi: err_rec: attempting to reset the capture channel` `[Fri Aug 22 20:54:24 2025] t194-nvcsi 13e40000.host1x:nvcsi@15a00000: csi5_stream_close: Error in closing stream_id=2, csi_port=2` `[Fri Aug 22 20:55:38 2025] tegra-camrtc-capture-vi tegra-capture-vi: corr_err: discarding frame 0, flags: 0, err_data 131072` ---
**Author:** ![ShaneCCC](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/shaneccc/32/14043_2.png) [@ShaneCCC](https://forums.developer.nvidia.com/u/ShaneCCC)\ **Post date:** [August 28, 2025, 7:14am UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/12 "2025-08-28T07:14:22Z")
This message tell unable capture frame data from the sensor. Maybe consult with E-CON for the solution. ---
**Author:** ![enrique.ramirez](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/enrique.ramirez/32/273049_2.png) [@enrique.ramirez](https://forums.developer.nvidia.com/u/enrique.ramirez)\ **Post date:** [August 28, 2025, 1:40pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/13 "2025-08-28T13:40:44Z")
Yes, it looks to be a problem with the application used. My theory is that the external trigger may not be activated or handled correctly by the application, causing the timeout errors as no data is received from the sensor. As ShaneCC it would be better to as E-CON, or invest time reviewing the application to find the problem. Embedded SW Engineer at RidgeRun Contact us: [support@ridgerun.com](mailto:support@ridgerun.com) Developers wiki: [https://developer.ridgerun.com](https://developer.ridgerun.com) Website: [www.ridgerun.com](http://www.ridgerun.com) ---
**Author:** ![Dharmalingam.K](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/dharmalingam.k/32/364066_2.png) [@Dharmalingam.K](https://forums.developer.nvidia.com/u/Dharmalingam.K)\ **Post date:** [September 11, 2025, 1:51pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/15 "2025-09-11T13:51:13Z")
Hi, Please write to “camerasolutions@e-consystems.com“. Our camera solutions expert will assist you. ---
**Author:** ![system](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/system/32/68080_2.png) [@system](https://forums.developer.nvidia.com/u/system)\ **Post date:** [September 25, 2025, 1:51pm UTC](https://forums.developer.nvidia.com/t/v4l2-buffer-errors-initialization-bug-with-multi-camera-sync-on-jetson/343123/16 "2025-09-25T13:51:50Z")
Closed on September 25, 2025, 1:51pm UTC This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.