Hello,
My team and I are trying to bringup a managed switch that uses the IMX6ULL as the host processor for the KSZ8567. Essentially, we've patched the DSA device driver for the KSZ9477 for the KSZ8567. See the patch file I've added to this question. We've also edited the device tree used by uboot and the linux kernel (using u-boot-imx and linux-imx) - see a snippet of the device tree below which describes the DSA topology.
&fec1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_enet1>;
phy-mode = "rmii";
status = "okay";
fixed-link {
speed = <100>;
full-duplex;
};
};
&i2c1 {
clock-frequency = <100000>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_i2c1>;
status = "okay";
switch@5f {
compatible = "microchip,ksz8567";
reg = <0x5f>;
ports {
#addess-cells = <1>;
#size-cells = <0>;
port@0 {
reg = <0x00>;
label = "lan1";
};
port@1 {
reg = <0x01>;
label = "lan2";
};
port@2 {
reg = <0x02>;
label = "lan3";
};
port@3 {
reg = <0x03>;
label = "lan4";
};
port@4 {
reg = <0x04>;
label = "lan5";
};
port@5 {
reg = <0x05>;
label = "cpu";
ethernet = <&fec1>;
phy-mode = "rmii";
fixed-link {
speed = <100>;
full-duplex;
};
};
};
};
};
We setup a Linux bridge with the following commands.
ip link set eth0 up ip link set lan5 up ip link set lan4 up ip link set lan3 up ip link set lan2 up ip link set lan1 up ip link add name br0 type bridge vlan_filtering 1 ip link set dev lan5 master br0 ip link set dev lan4 master br0 ip link set dev lan3 master br0 ip link set dev lan2 master br0 ip link set dev lan1 master br0 ip addr add 10.1.1.100/24 dev br0 ip link set dev br0 up
However we are seeing from ping tests from two hosts connected on each of the switch ports that they occasionally drop packets. In the following image, you can see that Seq 41 ICMP echo is dropped.
The same setup results in iperf3 TCP test which shows no packet transfer.
Likewise for an iperf UDP test, we can see 40% packet drop at 100Mbps.
Ultimately we've tried the following:
1. Manually set offloaded bridge forwarding database entires
2. Turning off auto-negotiation and force setting speed to 100Mbps, full duplex.
3. It is documented in KSZ8567 errata that EEE so we disabled that in all link partners.
Ultimately none of what we've tried helped so far.
My questions are:
1. Is the RMII backbone to the IMX6ULL problematic for the KSZ8567? Do we need to use a 1Gbit backbone for the CPU port instead?
2. Do we need to patch the fec controller in the linux-imx to work with KSZ switches?
