Tool/software:
Hello Support Team,
We are developing a custom board based on AM62L.
This board uses the DP83822 Ethernet PHY, which is recognized at PHY Address=9 and operates with the TI DP83822 driver.
[ 3.787182] davinci_mdio 8000f00.mdio: phy[9]: device 8000f00.mdio:09, driver TI DP83822
Issue
When the AM62L custom board and a Windows PC are connected via LAN, communication sometimes fails.
Normally, the link comes up at 100Mbps/Full, and communication with the Windows PC works correctly:
[ 6170.238949] ... eth0: Link is Up - 100Mbps/Full - flow control rx/tx
In this state, ping works fine.
However, sometimes the following messages appear, and the link speed downshifts to 10Mbps/Half:
[ 6173.776236] TI DP83822 8000f00.mdio:09: Downshift occurred from negotiated speed 100Mbps to actual speed 10Mbps, check cabling!
[ 6174.048950] ... eth0: Link is Up - 10Mbps/Half - flow control off
In this state, communication with the Windows PC fails (no ping response).
This issue occurs with both CAT6 and CAT6A cables, as it was observed when using either type.
Verification
We confirmed that both AM62L and the Windows PC are set to 100Mbps/Full, regardless of whether the downshift to 10Mbps/Half occurs or not.
- AM62L side:
root@custom_board:~# ethtool eth0 | grep -iE "speed|duplex"
Speed: 100Mb/s
Duplex: Full- Windows PC side:
PS C:\Users\user> Get-NetAdapter | Select-Object Status, LinkSpeed, FullDuplex
Status LinkSpeed FullDuplex
------ --------- ----------
Up 100 Mbps True
Questions
- What could be the possible causes of this behavior?
Thank you for your support.