DP83867IS: SGMII to SGMII

Hello Kajetan,

Yes, the link status refers to the (Ethernet) PHY link.

This application may cause issues as the SGMII also has an auto-negotiation process where one PHY would be required to act as the slave. In the current case both your PHYs are acting as master and are unable to resolve this.

Here is something you can try:

"The SGMII Auto-Negotiation process can be disabled and the SGMII speed mode can be forced to the MDI resolved speed. The SGMII forced speed mode can be enabled with the MDI auto-negotiation or MDI manual speed mode. SGMII Auto-Negotiation can be disabled through the SGMII_AUTONEG_EN register bit in the CFG2 register (address 0x0014)."

Another way to go about this problem is using a DP83869 in RGMII-SGMII bridge mode:

 [Linux-SOM => Ethernet => DP83867IS => SGMII => connector] [connector => SGMII => DP83869HM Bridge => RGMII => DP83867ERGZ-S-EVM => Ethernet => RJ45 => cable => Laptop/Switch/"house ethernet"]

Thanks,

Vibhu

Hi Vibhu,

thanks for the fast answer.

Sadly clearing the SGMII_AUTONEG_EN bit did not lead to the intended bahaviour right away. I will continue to dig into this on Monday with tho USB-MDIO tools.

Just to be on the save side, can you please review my DP83867 to DP83867 cabeling?

GND <-> GND

SI_p <-> SO_p

SI_n <-> SO_n

SO_p <-> SI_p

SO_n <-> SI_n

Hello Kajetan,

Sorry if my previous response wasn't clear.

In addition to disabling SGMII_AUTONEG_EN, you also need to force both the PHYs into a certain mode after disabling the PHYs' auto-negotiations. Use register 0x0000 bits 13, 12 and 8 for this.

Good luck with the rest of the debug.

Thanks,

Vibhu

Hello Vibhu,

thanks, I think I am still missing something. The link is Ethernet-connection is shown as 1000MBit on my laptop after full reset of the chip. After writing the registers I loose the Ethernet/MDI link. Doing this to both sides also does not help.

Here is my routine (debug-read, write registers to disable negotiation, reset chip without registers, debug-read again)

register 0000 read  0x1140
register 0001 read  0x796D
register 0002 read  0x2000
register 0003 read  0xA231
register 0004 read  0x0181
register 0005 read  0xCDE1
register 0006 read  0x006F
register 0007 read  0x2001
register 0008 read  0x4006
register 0009 read  0x0300
register 000a read  0x7800
register 000b read  0x0000
register 000c read  0x0000
register 000d read  0x0000
register 000e read  0x0000
register 000f read  0x3000
register 0010 read  0x5848
register 0011 read  0xBC02
register 0012 read  0x0000
register 0013 read  0x1C42
register 0014 read  0x29C7

register 0000 read  0x1140
register 0000 write 0x2300
register 0000 read  0x2100
register 0014 read  0x29C7
register 0014 write 0x2907
register 0014 read  0x2907
register 001f write 0x4000 (reset chip without registers)

register 0000 read  0x2100
register 0001 read  0x7949
register 0002 read  0x2000
register 0003 read  0xA231
register 0004 read  0x0181
register 0005 read  0x0000
register 0006 read  0x0064
register 0007 read  0x2001
register 0008 read  0x0000
register 0009 read  0x0300
register 000a read  0x0000
register 000b read  0x0000
register 000c read  0x0000
register 000d read  0x0000
register 000e read  0x0000
register 000f read  0x3000
register 0010 read  0x5848
register 0011 read  0x6B02
register 0012 read  0x0000
register 0013 read  0x0440
register 0014 read  0x2907

register 0000 : 0x2100
        bit[15]  0 RESET
        bit[14]  0 LOOPBACK
        bit[13]  1 SPEED SELECTION LSB
        bit[12]  0 AUTO-NEGOTIATION ENABLE
        bit[11]  0 POWER DOWN
        bit[10]  0 ISOLATE
        bit[ 9]  0 RESTART AUTO-NEGOTIATION
        bit[ 8]  1 DUPLEX MODE
        bit[ 7]  0 COLLISION TEST
        bit[ 6]  0 SPEED SELECTION MSB
        bit[ 5]  0 reserved
        bit[ 4]  0 reserved
        bit[ 3]  0 reserved
        bit[ 2]  0 reserved
        bit[ 1]  0 reserved
        bit[ 0]  0 reserved


register 0001 : 0x7949
        bit[15]  0 100Base-T4
        bit[14]  1 100BASE-TX FULL DUPLEX
        bit[13]  1 100BASE-TX HALF DUPLEX
        bit[12]  1  10BASE-Te FULL DUPLEX
        bit[11]  1  10BASE-Te HALF DUPLEX
        bit[10]  0 100BASE-T2 FULL DUPLEX
        bit[ 9]  0 100BASE-T2 HALF DUPLEX
        bit[ 8]  1 EXTENDED STATUS
        bit[ 7]  0 RESERVED
        bit[ 6]  1 MF PREAMBLE SUPPRESSION
        bit[ 5]  0 AUTO-NEGOTIATION COMPLETE
        bit[ 4]  0 REMOTE FAULT
        bit[ 3]  1 AUTO-NEGOTIATION ABILITY
        bit[ 2]  0 LINK STATUS
        bit[ 1]  0 JABBER DETECT
        bit[ 0]  1 EXTENDED CAPABILITY


register 0014 : 0x2907
        bit[15]  0 reserved
        bit[14]  0 reserved
        bit[13]  1 INTERRUPT_POLARITY
        bit[12]  0 reserved
        bit[11]  1 SPEED_OPT_ATTEMPT_CNT
        bit[10]  0 SPEED_OPT_ATTEMPT_CNT
        bit[ 9]  0 SPEED_OPT_EN
        bit[ 8]  1 SPEED_OPT_ENHANCED_EN
        bit[ 7]  0 SGMII_AUTONEG_EN
        bit[ 6]  0 SPEED_OPT_10M_EN
        bit[ 5]  0 reserved
        bit[ 4]  0 reserved
        bit[ 3]  0 reserved
        bit[ 2]  1 reserved
        bit[ 1]  1 reserved
        bit[ 0]  1 reserved

Any ideas?

Best regards,

Kajetan