Jetson Orin NX support MIPI CSI 4 lanes 4K 60fps

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

Hi,

I’m developing a driver for LT6911UXE support 4K 60fps.
Our hardware uses 4 lanes MIPI CSI for the connection between the LT6911UXE and the Jetson Orin NX.
This hardware can work well with the configuration for 4k 30fps, but if I change the configs for 4k 60fps, it does not work.

The pixel clock for 4k 30fps is 297000 KHz, and for the 4k 60fps is 594000 KHz. The pixel format is YUV422 8bit.
I’m wondering that can the Jetson Orin NX support 4k 60fps with 4 lanes? Or we need to use 8 lanes in this case?

Thank,

3

DPHY??

Skew calibration is required if sensor or deserializer is using DPHY, and the output data rate is > 1.5Gbps.
An initiation deskew signal should be sent by sensor or deserializer to perform the skew calibration. If the deskew signals is not sent, the receiver will stall, and the capture will time out.
You can calculate the output data rate with the following equation:

Output data rate = (sensor or deserializer pixel clock in hertz) * (bits per pixel) / (number of CSI lanes)
4

Hi,

Yes, the LT6911UXE will output DPHY.

Skew calibration is required if sensor or deserializer is using DPHY, and the output data rate is > 1.5Gbps

How to calculate the “output data rate” ?

5

If the pix_clk_hz is 594000 the output data rate is

594000*16/4 ~=2.4G

6

Hi,

So if I use 4k30, the data rate will be 297000/16*4 = 1.188G, no need the skew calibration. It’s reasonable why it worked.

How can I check the “skew calibration” on the driver side? Can I enable the logs or somethings to check it?

7

Please consult with vendor.

Thanks

8

Hi,

The vendor said to me that the Skew calibration signal is already sent.
Do i need to enable the deskew initial on the device tree?
Something like that “deskew-initial-calibration = <1>;”

9

Hi,

The convert chip only sends the skew calibration signal before the first frame, not for every frame. Does it work on this case?

10

Yes, current support sends the skew calibration signal before the first frame.

What’s the BSP version? Maybe upgrade to latest release to confirm.

11

Hi,

What’s the BSP version?

If you are asking for the Jetpack version, we are using Jetpack 6.2.

Also, If I try to reduce the pixel clock to 3500 (to make to data rate lower than 1.5Gbps), I can get the video frames, as below

image
image1148×868 133 KB

The vendor confirmed that the converter chip already sent the skew calibration signal before the first frame. But I don’t how to confirm this signal. Dow you have any idea on this?

12

You can modify the pix_clk_hz to make the output rate less than 1.5G and have below command to boost the clocks to try.

sudo su
echo 1 > /sys/kernel/debug/bpmp/debug/clk/vi/mrq_rate_locked
echo 1 > /sys/kernel/debug/bpmp/debug/clk/isp/mrq_rate_locked
echo 1 > /sys/kernel/debug/bpmp/debug/clk/nvcsi/mrq_rate_locked
echo 1 > /sys/kernel/debug/bpmp/debug/clk/emc/mrq_rate_locked
cat /sys/kernel/debug/bpmp/debug/clk/vi/max_rate |tee /sys/kernel/debug/bpmp/debug/clk/vi/rate
cat /sys/kernel/debug/bpmp/debug/clk/isp/max_rate | tee  /sys/kernel/debug/bpmp/debug/clk/isp/rate
cat /sys/kernel/debug/bpmp/debug/clk/nvcsi/max_rate | tee /sys/kernel/debug/bpmp/debug/clk/nvcsi/rate
cat /sys/kernel/debug/bpmp/debug/clk/emc/max_rate | tee /sys/kernel/debug/bpmp/debug/clk/emc/rate
13

Hi,

Yes, I tried this before.
By using the pixel clock 3500 and boost the clocks, I can get the frame, as the previous reply.

14

What’s the trace log

15

Hi,

I can get the frames, by reset the convert chip many many times.
I think the problem is the convert chip only send the “skew calibration signal” 1 time before the first frame, and the Jetson can not catch this calibration signal.

What do you think?
Do you think a burst of calibration signal will be a solution on this case?

16

I can’t tell but you can try it.

Thanks

17

Hi,

I can get the frames well.
Need to add a function to restart the MIPI output from the converter chip before starting the stream, then it worked.
It seems like the Jetson can not catch the skew calibration signal from the converter chip. The restart function is a solution in this case.

Thank you so much for your help.

19

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