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Original question:

DS125BR820: AER fail issue

DS125BR820: AER issue

Patrick Chen
Mastermind 8875 points
Part Number: DS125BR820

Hello

       Customer happen AER issue.

       Attached are testing results. A:  before tuning re-driver (AER fail as below setting) B. After tuning re-driver (AER Pass as below setting).  Customer would like to know the root cause why tuning TX (EQ Level 4 &VOD level 1) and RX ( EQ level 1 & VOD Level 6). The AER issue will be pass.  Below is customer questions : 

 

  1. Could you help clarify why these setting will pass AER? Has any relationship between AER and these EQ/VOD settings ?
  2. If customer need to setting correct parameters to pass AER, has any tuning reference doc or step to customer to avoid AER issue happen on future? Thank you.   

BR

Patrick

  • 0
    TI__Mastermind 43795 points

    Hi Patrick,

    What kind of AER was reported?  The linear equalization is purely at the electrical level so it can only help to compensate the signal attenuation. 

    Most AER reports are correctable and reported as additional information or warning only.  The typical format is shown below.

    2.3 AER error output

When a PCIe AER error is captured, an error message will be output to
console. If it's a correctable error, it is output as a warning.
Otherwise, it is printed as an error. So users could choose different
log level to filter out correctable error messages.

Below shows an example:
0000:50:00.0: PCIe Bus Error: severity=Uncorrected (Fatal), type=Transaction Layer, id=0500(Requester ID)
0000:50:00.0:   device [8086:0329] error status/mask=00100000/00000000
0000:50:00.0:    [20] Unsupported Request    (First)
0000:50:00.0:   TLP Header: 04000001 00200a03 05010000 00050100

In the example, 'Requester ID' means the ID of the device who sends
the error message to root port. Pls. refer to pci express specs for
other fields.

    From an electrical - link training standpoint, going to a lower VOD should help signal the endpoint and root complex to apply additional gain to the incoming signal.  Using the high VOD can overdrive the low frequency signal information and keep the PCIe system components at the low boost setting in a sub-optimal link training solution.

    Regards,

    Lee

  • 0 in reply to Lee Sledjeski
    Mastermind 8875 points

    Dear Lee

                      please refer to linux command as below for AER issue. Customer thinks AER it is a issue. And If tuning above EQ/VOD setting. AER was pass. Customer would like to know why tuning these parameters and AER will pass. They need to know the root cause. Could I send their test report by mail? Thank you. 

  • 0 in reply to Patrick Chen
    TI__Mastermind 43795 points
    Sure. Send the report by email.

    I would recommend that they look very closely at the PCIe system component settings for Tx and Rx equalization. If there is some difference, it is the root cause of the error. As I said in previous post. The lower redriver VOD is likely helping link equalization reach a more optimal result.

    Thanks and Regards,
    Lee