i.MX8MPlus EVK: PHY loopback on ENET_QOS

[abelal]

Hi experts,

I have the i.MX8MP EVK on which I am trying to develop a loopback test for ethernet PHYs. On the EVK, one PHY is connected to ENET/fec and the other is connected to ENET_QOS/eqos. I understand both of these use a different driver when it comes to hardware IP but the PHY handling is same.

Without connecting any ethernet cables I use phytool to switch the PHY to loopback mode by using the standard BMCR register of the PHY. Example for fec

phytool write eth0/1/0x0 0x6100

and in dmesg I get

[  466.592107] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
[  466.592938] fec 30be0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control off

I am able to receive the packets that I send on this interface making clear the loopback works. The RJ45 port LED for this interface also goes up.

However when I try to do the same with ENET_QOS/eqos the interface never goes up

phytool write eth1/1/0x0 0x6100

nothing in dmesg at this point nor do I receive the packets I send on the interface but the RJ45 port LED is on.

Can this behavior be explained? How can I make the eqos work when PHY is in loopback mode?

[Zhiming_Liu]

The bit of Loopback mode in QOS is 12:

But the Bit12  of 0x6100 you used is 0, you  need change this value.

[abelal]

Hi @Zhiming_Liu ,

You are referring to the MAC loopback capability however please note that I am trying a different scenario where I am putting the PHY in the loopback mode (not the MAC) and it works as expected for the FEC interface and not the EQOS.

[abelal]

Hello team,

No updates/response here?