DP83867IR: Intermittent link down

Hi Sato,

Can you check if the bootstrap settings are correct? Are the voltages on the strap pins during power-up the correct value for your customer's configuration?

If the above is fine, can you provide two sets of register dumps? I would like to see the data in registers 0x00 to 0x1F when the device is link up at 1Gb and when the device is link up at 100Mb.

Regards,

Adrian Kam

Hello Adrian-san,

Thank you for your support.

Customer confirmed bootstrap settings are correct as they designed.

And here are the register information from 0x00 to 0x1F for both link down case and link up case.

Difference is seen in 0x01 and 0x13 value. Could you please confirm this and let me know if you have any findings? 

Best regards,

Hi Sato,

Can you clarify what you mean by "link down to 100Mb"? Does this mean the link partner goes from 1Gb to 100Mb, which then causes link to drop? If so, does the link partner have auto-negotiation capabilities, or is the link partner in forced mode and the speed is being changed manually?

In addition, can you try enabling Robust Auto-MDIX and Fast Auto-MDIX in register 0x001E?

Regards,

Adrian Kam

Hello Adrian-san,

Customer tried enabling Auto-MDIX and Fast Auto-MDIX but there was no improvement. They provided register settings for this case.

>Does this mean the link partner goes from 1Gb to 100Mb, which then causes link to drop?

Yes it does. And link partner is also Auto-negotiation.

DP83867IR can linkup 1Gb, but irregularly linkdown happens. It is recovered soon, so TCP/IP communication is kept.

If connecting with forcing 100Mb, the phenomenon doesn't happen.  

Best regards,

Hi Sato,

I have a few questions:

1. Can you double confirm that Robust Auto-MDIX and Fast Auto-MDIX has been tried? The register data you provided seems to be the same as last time with Robust Auto-MDIX (bit 9 of register 0x001E) and Fast Auto-MDIX (bit 8 of register 0x001E) disabled.
2. When the link down scenario occurs, how long does it last until it recovers? How long does the link partner stay at 100Mb before going back to 1Gb?
3. What link partner device is being used?

Regards,

Adrian Kam

Hello Adrian-san,

1.

Sorry for inconvenient. I reattached register information. It didn't give improvement.

2.

Customer tried two connection destinations, one is Windows10 and the other is Linux.

In case of connection is Windows10, it takes about 500ms for recover from linkdown to linkup(1Gb).

In case of connection is Linux, it is about 30ms.

(Customer is not sure if 100Mb link is established during linkdown.)

3. 

Windows10(DELL Latitude5580) or Linux(RaspberryPI3)

Best regards,

Hi Sato,

I have a few questions:

1. Can I get the register information for registers 0x31, 0x6E, and 0x6F as well? Two sets like before with 100Mb link down scenario and 1Gb link up scenario. Since these registers are extended registers, the customer will need to use the extended address space access procedure outlined in section 8.4.2.1 in the datasheet to get the information.
2. Is the temporary drop from 1Gb to 100Mb intended for the application? Or is this a issue that occurs occasionally with the link partner?

Regards,

Adrian Kam

Hello Adrian-san,

1. Customer provided the register information. I attached file in below.

There are three cases data in the file.

• Left data: (Auto-negotiation) the case of LinkUp 1Gb and then LinkDown(1st time)
• Center data: (Auto-negotiation) Linkup 1Gb after 1st time linkdown(left data) and then LinkDown(2nd time)
  There are difference in register data in 1st time linkdown and 2nd time linkdown. So customer provided both data for reference.
  
  
• Right data: the case of 100Mb full-duplex LinkUp. and then linkdown by unplug the LAN cable manually for experimental purpose.

DP83867IR_RegisterInfo_0304.xlsx

2. Linkdown is not intentional and it occurs occasionally with link partner.

Please let me know if you find anything to improve the issue.

Best regards,

Hi Sato,

Looking at register 0x0031, it seems that bit[7] is set to 1 when it should be 0. Can you see if your issue is improved by clearing bit[7] of register 0x0031 to 0? Also, can you double check the voltage on the "RX_DV/RX_CTRL" strap and make sure that is is set to mode 3? If bit[7] of register 0x0031 is set to 1, then it means that the strap is not correctly set to either mode 3 or 4.

Regards,

Adrian Kam

Hello Adrian-san,

Customer changed register 0x0031 bit[7] to 0, however they couldn't see improvement.

Please refer register information with the change.

DP83867IR_RegisterInfo_0305.xlsx

Are there any other things we should to confirm?

Best regards,