[FAQ] AM6422: How to configure the PCIe align with the simulation results.?

Hi wang shu,

Thanks for your query.

Which SDK you are working on ?

Regards

Ashwani

Hi Ashwani,

We are using PROCESSOR_SDK_AM64X.

BR

Shu

Hi Bin,

We confirmed with the SI engineer. they just close the "Deemphasis" which mean set the Deemphasis code to 0dB.

There are lots of PCIe setting in the phy-cadence-torrent.c file, but none of them describe about deemphasis or emphasis.

Do you know how to change the .c file to make the deemphasis to 0dB or close?

Regards,
Shu

Hi Shu,

The PCIe PHY deemphasis value shouldn't be changed.

Where did you get the IBIS model? from TI? I'd like to understand how it gives the 0dB result.

Hi Bin,

Yes, the IBIS model is from TI for AM64x. Do you need to know the simulator that our supplier used?

BR,
Shu

Hi Wang,

Do you know who from TI delivered the IBIS model to you? I'd like to discuss about the enumeration result internally.

Hi Bin,

Sorry to reply late. I download the IBIS-AMI model from TI website. It has a installer name "SPRM731-1.0-windows-x64-installer". Then you can see the difference IBIS models. I use the model in pcie2 folder.

Regards,
Shu

Hi Shu,

I am working internally to understand this. I will post here once I have any update.

Hello Shu, 

Please refer below inputs from the device expert:

We typically do not allow any updates to SerDes registers because our software has configured them as required for the respective peripheral to pass its industry standard certification tests.

Regards,

Sreenivasa

Hi Sreenivasa,

So does the chip support adaptive equalization? if yes, maybe we won't need worry about the signal quality. the chip will find the best way by itself. if not, why the chip doesn't need adjust the configuration? it doesn't know what load and hardware condition i am using on my board.

Best Regards,
Shu

Hello Shu,

Thank you.

Let me check with the expert.

Would you be able to share the application use case?

Regards,

Sreenivasa

Hi Sreenivasa,

We connect the AM6422 to a regular FPGA with PCIe. the simulation show the best result to disable equalization. we don't know how to do it. The FPGA replied they support adaptive equalization to adjust the signal quality automatically. we don't need to disable the equalization by ourselves.

now we wish the know the AM6422 design. does it support the adaptive equalization too?

Regards,
Shu

Thanks Sreenivasa, we will keep the default configuration of the PCIe.