DS90UB954-Q1: Communication timing setting register of CSI-2

Hello Tomoaki

Our customer is facing the overflow of CSI-2 that same as you.
Did your customer fix it? Do you know how to fix it?

Regards,
Nao

Hi, Jiashow

Thank you for your reply.
Our customer tried to change this register.
They changed that all register value are minimum.
And then, Their system works without the buffer overflow.
BUT, AC timing does not meet CSI-2 spec.

So, do you have any advice of each register settings?

Regards,
Nao

Hi, Jiashow

No... I guess their system is fixed date rate.
Do you have any idea?

Regards,
Nao

Hi Nao,

Could you provide more details of their system? What imager are they using? What's the frame rate? Bits per pixel?

Best,
Jiashow

Hi, Jiashow

Their system is NOT using popular imager.
They use IC which has CSI-2 I/F and details are an undisclosed.

Other their system information.
1. The frame rate is 7kpbs.
2. Bits per pixel is 800Mbps/lane (They use 4 lane.)

Regards,
Nao

Hi Jiashow-san,

Our customers have not solved this issue yet.
According to their analysis, the CSI-2 output timing in LP mode is different from the input and becomes slow.
For example, the input LP-11 state is 200 ns, but the output it is very long, 600ns.
Packet transmission time in HS mode is the same as input.
The output timing gradually delays for each LP mode, so it seems that buffer overflow will eventually occur.

They think that timing adjustment like MR_TCK_PREP is not optimal automatically.
Should user usually adjust these registers?

Best regards,
Tomoaki Yoshida

Hi, Jiashow

Do you have any update for my information?
Should I rise new thread?

Regards,
Nao

Hi, Jiashow

Our customer issues is as same as Tomoaki's case.
> For example, the input LP-11 state is 200 ns, but the output it is very long, 600ns.

Hence, our customer tried to change the 0x47(=CSI0_THS_EXIT) register on UB954.
BTW, LP-11(idle time) does not change in this register value.

How do we change the LP-11 value?

Regards,
Nao

Hi, Jiashow

Thank you for your quick reply.
System requirement of our customer is "Bits per pixel is 800Mbps/lane (They use 4 lane.)".
And CSI_PLL_CTL(0x1F) value is 0x02.
I guess CSI-2 timing is same if I believe our customer's comment.

Please let me know if I need to check other registers.

Regards,
Nao

Hi, Jiashow

Yes. My customer is using one sensor.

Here is packet waveform of my customer system.
The yellow is CSI input data of UB953).
The blue is CSI output data of UB954.

Data bit timing is almost same. (560ns)
But, Idle timing is difference. Input data is 240ns. Output data is 600ns.
Our customer want to know how to fix it?
Do you have any ideas?

Regards,
Nao

Hi, Jiashow

This is zoom-out waveform.
Could you check it? Please tell me the comment.

I will ask my customer about #1 and #2 question.
#1 Are you seeing any errors other than buffer overflow?
     - Please tell me the address of registers to check  just in case.
#2 Could you zoom-in on your input side to provide the timing relationship LP-11, LP-01, LP-00, HS transition and make sure they meet the CSI spec?

Regards,
Nao

Hi Nao,

From the deserializer could you check registers 0x54-0x57 for any errors?

From the serializer could you check registers 0x5C-0x64?

Hi, Jiashow

Thank you for your update.
I asked our customer it. Please wait.

Please let me check again.
Is there a way to change the value of LP - 11?

Regards,
Nao

Hi, Jiashow

Do you have any update about this?

>Is there a way to change the value of LP-11?

Regards,
Nao

Hi Nao,

There's no register where you can change the timing of LP-11. Could you provide the registers and values the customers are setting? (for example, are they only forwarding one port to the CSI?)

Best,
Jiashow

Hi, Jiashow

Thank you for your update.

There are some error in register 0x5C-0x64 of UH953.
Our customer is confirming this error now.
I will get back to you, if I get new information.

One more thing, I will ask our customer that I can send you their register value.

Regards,
Nao

Hi Nao,

Has customer gotten back to you regarding this issue?

Best,
Jiashow

Hi, Jiashow

UH953 system is developing other customer.
So, my customer currently inquiring with other customer.
I will tell you soon if I get reprocess of our customer.

Regards,
Nao