Re: phy: fixed link 1000 or 100 set with autoneg off

Re: phy: fixed link 1000 or 100 set with autoneg off

[Bagas Sanjaya]

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On Mon, Oct 23, 2023 at 03:01:10PM +0800, Jia, Fang wrote:
> Hi Experts,
> 
> We use NXP LS1046 board and face an issue about the eth interface speed.
> 
> 1) Scenario
> 
> we set fixed link 1000Mb/s in device tree.
> 
> However, after we set the auto-neg off, then the eth1's speed changed to 10M
> and Duplex changed to Half.
> The value of /sys/class/net/eth1/speed is 10 and /sys/class/net/eth1/duplex
> is half
> 
> 2) Log is as following.
> 
> # ifconfig eth1 up
> # ethtool eth1
> Settings for eth1:
>         Supported ports: [ MII ]
> 
>         Supported link modes:   1000baseT/Full
>         Supported pause frame use: Symmetric Receive-only
>         Supports auto-negotiation: Yes
> 
> 
>         Supported FEC modes: Not reported
> 
> 
>         Advertised link modes:  1000baseT/Full
>         Advertised pause frame use: Symmetric Receive-only
> 
> 
>         Advertised auto-negotiation: Yes
>         Advertised FEC modes: Not reported
>         Speed: 1000Mb/s
>         Duplex: Full
>         Port: MII
>         PHYAD: 1
>         Transceiver: internal
>         Auto-negotiation: on
>         Supports Wake-on: d
>         Wake-on: d
>         Current message level: 0xffffffff (-1)
>                                drv probe link timer ifdown ifup rx_err
> tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000
>         Link detected: yes
> 
> # ethtool -s eth1 autoneg off
> # ethtool eth1
> Settings for eth1:
>         Supported ports: [ MII ]
>         Supported link modes:   1000baseT/Full
>         Supported pause frame use: Symmetric Receive-only
>         Supports auto-negotiation: Yes
>         Supported FEC modes: Not reported
>         Advertised link modes:  1000baseT/Full
>         Advertised pause frame use: Symmetric Receive-only
>         Advertised auto-negotiation: No
>         Advertised FEC modes: Not reported
>         Speed: 10Mb/s
>         Duplex: Half
>         Port: MII
>         PHYAD: 1
>         Transceiver: internal
>         Auto-negotiation: off
>         Supports Wake-on: d
>         Wake-on: d
>         Current message level: 0xffffffff (-1)
>                                drv probe link timer ifdown ifup rx_err
> tx_err tx_queued intr tx_done rx_status pktdata hw wol 0xffff8000
>         Link detected: yes
> 
> 3) After code tracing, we found that:
> 
> phy_state_machine()
> 	state PHY_RUNNING: phy_check_link_status()
> 		phy_read_status()
> 			genphy_read_status()
> 				genphy_read_status_fixed()
> 
> In genphy_read_status_fixed(), the speed and duplex changed.
> It seems like the bmcr value is always 0x1000 from swphy_read_reg().
> 
> After revert the commit 726097d6d6d(net: phy: improve auto-neg emulation in
> swphy), then the Speed and Duplex shown comes back to 1000M and Full.
> 

Thanks for the regression report. I'm adding it to regzbot

#regzbot ^introduced: 726097d6d6d8e9

-- 
An old man doll... just what I always wanted! - Clara

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