Packet Loss with AR8031 PHY on STM32MP1 - Direct Connection to Linux Host

[DmitryKon]

Hello everyone,

I'm experiencing an issue with network packet loss in a setup using the AR8031 PHY with an STM32MP1 system and would appreciate any insights or suggestions.

Problem Description:

• Significant (60-90%) packet loss when STM32MP1 board is directly connected to a Linux host via Ethernet

• No packet loss when the same board is connected through an Ethernet switch

• Issue occurs consistently with direct host connections

Tested/Verified so far:

• Multiple known-good Ethernet cables (CAT5e/CAT6)

• Different Linux hosts

• Link speed and duplex settings (100M/1G, full/half duplex), 100M works fine with no packet loss

• Enable/disable various PHY driver quirks (qca,disable-smarteee, qca,disable-hibernation-mode, qca,clk-out-strength, qca,keep-pll-enabled, qca,smarteee-tw-us-1g)

Device Tree Snippet:

&ethernet0 {                                                                                                                                                                                               
        status = "okay";                                                                                                                                                                                   
        pinctrl-0 = <&ethernet0_rgmii_pins_a>;                                                                                                                                                             
        pinctrl-1 = <&ethernet0_rgmii_sleep_pins_a>;                                                                                                                                                       
        pinctrl-names = "default", "sleep";                                                                                                                                                                
        phy-mode = "rgmii-id";                                                                                                                                                                             
        max-speed = <1000>;                                                                                                                                                                                
        phy-handle = <&phy0>;                                                                                                                                                                              
        nvmem-cells = <&ethernet_mac_address>;                                                                                                                                                             
        nvmem-cell-names = "mac-address";                                                                                                                                                                  
        phy-supply = <&eth_reg>;                                                                                                                                                                           
        st,eth-clk-sel;                                                                                                                                                                                    
                                                                                                                                                                                                           
        mdio0 {                                                                                                                                                                                            
                #address-cells = <1>;                                                                                                                                                                      
                #size-cells = <0>;                                                                                                                                                                         
                compatible = "snps,dwmac-mdio";                                                                                                                                                            
                phy0: ethernet-phy@0 {                                                                                                                                                                     
                        reg = <0>;                                                                                                                                                                         
                        qca,clk-out-frequency = <125000000>;                                                                                                                                               
                        qca,disable-smarteee;                                                                                                                                                              
//                      qca,disable-hibernation-mode;                                                                                                                                                      
//                      qca,clk-out-strength = <0>;                                                                                                                                                        
//                      qca,keep-pll-enabled;                                                                                                                                                              
//                      qca,smarteee-tw-us-1g = <128>;                                                                                                                                                     
//                      qca,smarteee-tw-us-100m = <24>;                                                                                                                                                    
                };                                                                                                                                                                                         
        };                                                                                                                                                                                                 
}; 

Questions:

1. Has anyone encountered similar issues with AR8031 PHY on STM32MP1?

2. Are there specific device tree properties for AR8031 that I might be missing?

3. Any known workarounds/specific settings for direct host connections?

Additional Info:

• Kernel version: 6.1.28

• ST OpenSTLinux 6.1