Initial deskew parameters in Jetpack 5

Robotics & Edge Computing Jetson & Embedded Systems Jetson AGX Orin
1

Hello,

I am using a serdes setup with a 2gbps link. I have read in the documentation that a deskew signal was necessary for signals with a bandwidth superior to 1.5 gbps.

I have no issue opening my camera with bandwidth up to 2.5 gbps.

However, I have noticed that the initial deskew signal is not activated on my deserializer. So I have activated it, but I cannot see any difference. So I have several questions:

  • Why does it seem I can open my camera at 2.5 Gbps without setting up the initial deskew?
  • Is there a way to tell that the initial deskewing is indeed properly working?
  • What should be the initial deskew width? I can set it from 132k UI to 832k UI
  • Do we agree that periodic deskew is not supported?
  • It seems from the kernel sources that I don’t have to specify it in the device tree, am I right?

I thank you for your help!

3

hello louis.guerlin,

may I confirm your Jetpack release version, and, please also share your test pipeline to access to the camera stream for reference?
FYI, it’s RCE firmware to handle deskew calibration, which is a must if data-rate > 1.5 Gbps.

4

Hello JerryChang,

Thanks for your help!

We support Jetpack 5.0.2, up to 5.1.2, and in the documentation, I did read that the deskew was a must have at rates>1.5gbps for all these.

The full pipeline is the following:

  • 2 camera sensor in 4 lanes with a pixel clock of 57.6 MHz outputing RAW10
  • 2x4 Serializer (MAXIM)
  • Deserializer in 4x2 (MAXIM)
  • Jetson Orin AGX receiving 2 virtual channels from the deserializer in 1x2 lane mode, with a datarate of 2gbps per lane (deskew needed but not activated in the serializer or deserializera as of now)

Is it possible that deskew is bypassed in 2 lane mode? Because, I think I did the test, I start to have stability issues above 1.5 gbps in 4 lanes.

5

hello louis.guerlin,

it should not.

it might due to sensor pixel clock configurations,
please refer to SerDes Pixel Clock section, and review your device tree property settings.

6

Hello Jerry Chang,

When switching to 4 lanes, I did have to adjust the SerDes Pixel Clock. But why would instability be caused by their configuration?

Finally, do you know the answer to these two questions?

Thanks again!

7

hello louis.guerlin,

as mentioned, it’s RCE firmware to handle deskew calibration, it’ll enable pixel parser when deskew calibration has completed.
you may try updating the RCE firmware with debug flag enabled. it’ll report deskew related messages.
for example,
please refer to Topic 268833,
you may apply JP-5.1.2 camera firmware update, which has some bug fixes to update deskew algorithm, and also stability improvements.
in the same discussion thread, I’ve also attach the camera firmware with debug flag enabled.

9

This topic was automatically closed 14 days after the last reply. New replies are no longer allowed.