status register value always reads 0x0000 in eth_mcux_phy_setup

[armandciejak]

Describe the bug
In drivers/ethernet/eth_mcux.c:eth_mcux_phy_setup ENET_ReadSMIData is called right after calling ENET_StartSMIRead without waiting for the MII interrupt, which leads to the value of the status variable to always be 0x0000.

The correct sequence is documented in the i.MX RT1060 reference manual in chapter 41.7.17.4.

I've hacked the eth_mcux_phy_setup function to poll the EIR register until the MII interrupt bit is set before reading the status register and it works (i.e. the content of the status register is correctly retrieved).

Expected behavior
Status register value is correctly retrieved.

Impact
Calling eth_mcux_phy_setup has no effect.

Environment (please complete the following information):

• OS: Linux (Ubuntu 18.04)
• Toolchain: Zephyr SDK 0.10.3
• Commit: 9f7cccc

Additional context
This problem occurs on a custom board equipped with the IMXRT1062 MCU but should occur as well with the MIMXRT1060-EVK.

[armandciejak]

I tested it on the MIMXRT1060-EVK board and the problem is the same.