DP83826E: Issue in communication using DP83826E PHY with our custom board

Hi Gaurav,

Its good that physical link detection is working. Just to confirm, are you able to access registers through your software? It seems like the software reports a link up so you may be getting register access but I want to be sure.

Have you performed any loopback testing? If the PHY can respond to registers, but data is not getting through the PHY, a good step to try is MII loopback. This is described in our DP83826 troubleshooting guide.

Best,

Shane

Hi Gaurav,

In addition to Shane's suggestions, could you please share the procedure for testing communication? Do ethtool and ifconfig report the expected link and speed status, with static IP used for ping between link partners?

Thank you,
Evan

Hi Shane, 
Yes, I am able to access the registers through my software and read their status.

[ 3962.713300] am-cpsw-nuss 8000000.ethernet eth1: Link is Up - 100Mbps/Full - flow control rx/tx
[ 3967.823727] am-cpsw-nuss 8000000.ethernet eth1: Link is Down


ethtool eth1
Settings for eth1:
        Supported ports: [ TP    MII ]
        Supported link modes:   10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Supported pause frame use: Symmetric
        Supports auto-negotiation: Yes
        Supported FEC modes: Not reported
        Advertised link modes:  10baseT/Half 10baseT/Full
                                100baseT/Half 100baseT/Full
        Advertised pause frame use: Symmetric
        Advertised auto-negotiation: Yes
        Advertised FEC modes: Not reported
        Link partner advertised link modes:  10baseT/Half 10baseT/Full
                                             100baseT/Half 100baseT/Full
        Link partner advertised pause frame use: Symmetric Receive-only
        Link partner advertised auto-negotiation: Yes
        Link partner advertised FEC modes: Not reported
        Speed: 100Mb/s
        Duplex: Full
        Auto-negotiation: on
        Port: Twisted Pair
        PHYAD: 4
        Transceiver: external
        MDI-X: Unknown
        Supports Wake-on: gs
        Wake-on: d
        SecureOn password: 00:00:00:00:00:00
        Current message level: 0x000020f7 (8439)
                               drv probe link ifdown ifup rx_err tx_err hw
        Link detected: yes

I have assigned static IP addresses and checked the loopback by pinging  the same IP. The logs are attached below.

ifconfig
eth0      Link encap:Ethernet  HWaddr ------present----
          inet addr:192.168.30.122  Bcast:192.168.30.255  Mask:255.255.255.0
          inet6 addr: fe80::6670:60ff:feff:f338/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:510 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:24824 (24.2 KiB)

eth1      Link encap:Ethernet  HWaddr ----present----
          inet addr:192.168.31.122  Bcast:192.168.31.255  Mask:255.255.255.0
          inet6 addr: fe80::648a:5eff:fe9f:aa85/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:91 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:9126 (8.9 KiB)

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:1749 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1749 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:153468 (149.8 KiB)  TX bytes:153468 (149.8 KiB)

root@ ping 192.168.30.122
PING 192.168.30.122 (192.168.30.122): 56 data bytes
64 bytes from 192.168.30.122: seq=0 ttl=64 time=0.247 ms
64 bytes from 192.168.30.122: seq=1 ttl=64 time=0.526 ms

# ping 192.168.31.122
PING 192.168.31.122 (192.168.31.122): 56 data bytes
64 bytes from 192.168.31.122: seq=0 ttl=64 time=0.248 ms
64 bytes from 192.168.31.122: seq=1 ttl=64 time=0.528 ms

Since I have connected the PHY for working in Enhancement mode with RMII this is my hardware layout .

Please consider the black marked part as DNP .
 

Yes ethtool and ifconfig report the expected link and speed status. Although ethtool is reporting RX errors.

ethtool -S eth1
NIC statistics:
     p0_rx_good_frames: 654
     p0_rx_broadcast_frames: 494
     p0_rx_multicast_frames: 160
     p0_rx_crc_errors: 0
     p0_rx_oversized_frames: 0
     p0_rx_undersized_frames: 0
     p0_ale_drop: 0
     p0_ale_overrun_drop: 0
     p0_rx_octets: 48764
     p0_tx_good_frames: 0
     p0_tx_broadcast_frames: 0
     p0_tx_multicast_frames: 0
     p0_tx_octets: 0
     p0_tx_64B_frames: 514
     p0_tx_65_to_127B_frames: 106
     p0_tx_128_to_255B_frames: 34
     p0_tx_256_to_511B_frames: 0
     p0_tx_512_to_1023B_frames: 0
     p0_tx_1024B_frames: 0
     p0_net_octets: 48764
     p0_rx_bottom_fifo_drop: 0
     p0_rx_port_mask_drop: 0
     p0_rx_top_fifo_drop: 0
     p0_ale_rate_limit_drop: 0
     p0_ale_vid_ingress_drop: 0
     p0_ale_da_eq_sa_drop: 0
     p0_ale_block_drop: 0
     p0_ale_secure_drop: 0
     p0_ale_auth_drop: 0
     p0_ale_unknown_ucast: 0
     p0_ale_unknown_ucast_bytes: 0
     p0_ale_unknown_mcast: 0
     p0_ale_unknown_mcast_bytes: 0
     p0_ale_unknown_bcast: 0
     p0_ale_unknown_bcast_bytes: 0
     p0_ale_pol_match: 0
     p0_ale_pol_match_red: 0
     p0_ale_pol_match_yellow: 0
     p0_ale_mcast_sa_drop: 0
     p0_ale_dual_vlan_drop: 0
     p0_ale_len_err_drop: 0
     p0_ale_ip_next_hdr_drop: 0
     p0_ale_ipv4_frag_drop: 0
     p0_tx_mem_protect_err: 0
     p0_tx_pri0: 0
     p0_tx_pri1: 0
     p0_tx_pri2: 0
     p0_tx_pri3: 0
     p0_tx_pri4: 0
     p0_tx_pri5: 0
     p0_tx_pri6: 0
     p0_tx_pri7: 0
     p0_tx_pri0_bcnt: 0
     p0_tx_pri1_bcnt: 0
     p0_tx_pri2_bcnt: 0
     p0_tx_pri3_bcnt: 0
     p0_tx_pri4_bcnt: 0
     p0_tx_pri5_bcnt: 0
     p0_tx_pri6_bcnt: 0
     p0_tx_pri7_bcnt: 0
     p0_tx_pri0_drop: 0
     p0_tx_pri1_drop: 0
     p0_tx_pri2_drop: 0
     p0_tx_pri3_drop: 0
     p0_tx_pri4_drop: 0
     p0_tx_pri5_drop: 0
     p0_tx_pri6_drop: 0
     p0_tx_pri7_drop: 0
     p0_tx_pri0_drop_bcnt: 0
     p0_tx_pri1_drop_bcnt: 0
     p0_tx_pri2_drop_bcnt: 0
     p0_tx_pri3_drop_bcnt: 0
     p0_tx_pri4_drop_bcnt: 0
     p0_tx_pri5_drop_bcnt: 0
     p0_tx_pri6_drop_bcnt: 0
     p0_tx_pri7_drop_bcnt: 0
     rx_good_frames: 0
     rx_broadcast_frames: 0
     rx_multicast_frames: 0
     rx_pause_frames: 0
     rx_crc_errors: 0
     rx_align_code_errors: 0
     rx_oversized_frames: 0
     rx_jabber_frames: 0
     rx_undersized_frames: 0
     rx_fragments: 0
     ale_drop: 0
     ale_overrun_drop: 0
     rx_octets: 0
     tx_good_frames: 113
     tx_broadcast_frames: 0
     tx_multicast_frames: 113
     tx_pause_frames: 0
     tx_deferred_frames: 0
     tx_collision_frames: 0
     tx_single_coll_frames: 0
     tx_mult_coll_frames: 0
     tx_excessive_collisions: 0
     tx_late_collisions: 0
     rx_ipg_error: 0
     tx_carrier_sense_errors: 0
     tx_octets: 11558
     tx_64B_frames: 16
     tx_65_to_127B_frames: 77
     tx_128_to_255B_frames: 20
     tx_256_to_511B_frames: 0
     tx_512_to_1023B_frames: 0
     tx_1024B_frames: 0
     net_octets: 11558
     rx_bottom_fifo_drop: 0
     rx_port_mask_drop: 0
     rx_top_fifo_drop: 0
     ale_rate_limit_drop: 0
     ale_vid_ingress_drop: 0
     ale_da_eq_sa_drop: 0
     ale_block_drop: 0
     ale_secure_drop: 0
     ale_auth_drop: 0
     ale_unknown_ucast: 0
     ale_unknown_ucast_bytes: 0
     ale_unknown_mcast: 0
     ale_unknown_mcast_bytes: 0
     ale_unknown_bcast: 0
     ale_unknown_bcast_bytes: 0
     ale_pol_match: 0
     ale_pol_match_red: 0
     ale_pol_match_yellow: 0
     ale_mcast_sa_drop: 0
     ale_dual_vlan_drop: 0
     ale_len_err_drop: 0
     ale_ip_next_hdr_drop: 0
     ale_ipv4_frag_drop: 0
     iet_rx_assembly_err: 0
     iet_rx_assembly_ok: 0
     iet_rx_smd_err: 0
     iet_rx_frag: 0
     iet_tx_hold: 0
     iet_tx_frag: 0
     tx_mem_protect_err: 0
     tx_pri0: 113
     tx_pri1: 0
     tx_pri2: 0
     tx_pri3: 0
     tx_pri4: 0
     tx_pri5: 0
     tx_pri6: 0
     tx_pri7: 0
     tx_pri0_bcnt: 11558
     tx_pri1_bcnt: 0
     tx_pri2_bcnt: 0
     tx_pri3_bcnt: 0
     tx_pri4_bcnt: 0
     tx_pri5_bcnt: 0
     tx_pri6_bcnt: 0
     tx_pri7_bcnt: 0
     tx_pri0_drop: 0
     tx_pri1_drop: 0
     tx_pri2_drop: 0
     tx_pri3_drop: 0
     tx_pri4_drop: 0
     tx_pri5_drop: 0
     tx_pri6_drop: 0
     tx_pri7_drop: 0
     tx_pri0_drop_bcnt: 0
     tx_pri1_drop_bcnt: 0
     tx_pri2_drop_bcnt: 0
     tx_pri3_drop_bcnt: 0
     tx_pri4_drop_bcnt: 0
     tx_pri5_drop_bcnt: 0
     tx_pri6_drop_bcnt: 0
     tx_pri7_drop_bcnt: 0

Hi Gaurav,

Thank you for sharing the detailed logs. This could be an IP routing issue, addresses 192.168.30.122 and 192.168.31.122 share the same subnet with distinct IP address in the mask range.

Could you please try setting these static IPs with same subnet mask 255.255.255.0 :

eth0 to 192.168.30.122
eth1 to 192.168.30.123

Does ping work in this case?

Thank you,
Evan

Hi Evan, 
We tried that it is not working .

Regards
Gaurav

Hi Gaurav,

Thanks for confirming. In the ethtool log, I see incrementing values for "rx_good_frames" and "tx_good_frames". This suggests link is healthy with packet transfer over MDI and MAC, but some routing issue is preventing ping acknowledgment.

Are both PHYs connected to the same host, and is this topology required in your system? If possible, please try ping with unique {Host+PHY} endpoints.

Appnote reference for debug: https://www.ti.com/lit/an/spradj8/spradj8.pdf

Thank you,
Evan