topic Re: i.mx8m mini ethernet reset pin pulled low after boot up in i.MX Processors

i.mx8m mini ethernet reset pin pulled low after boot up

Rajender — Mon, 13 Dec 2021 07:24:23 GMT

Hi,

We have designed a custom board with i.mx8m mini with RTL8211FDI realtek ethernet PHY IC. We have connected GPIO4_IO22 to ethernet PHY reset pin. 4.7k ohm pull up resistor is placed on this net.

During boot up, Reset pin of ethernet phy is pulled up but after completion of booting Reset pin is pulled to low and ethernet phy is not turning on.

We have taken i.mx8m plus as reference in schematic and device tree (as it uses same ethernet PHY).

We tried to keep GPIO internal pull up high but still observed same.

Please guide us how to proceed on this.

Thanks,

Rajender.

Re: i.mx8m mini ethernet reset pin pulled low after boot up

igorpadykov — Mon, 13 Dec 2021 09:24:38 GMT

Hi Rajender

what uboot used in the case, in nxp uboot one can try to debug it in function fec_gpio_reset() :

https://source.codeaurora.org/external/imx/uboot-imx/tree/drivers/net/fec_mxc.c?h=lf_v2021.04

Best regards
igor

Re: i.mx8m mini ethernet reset pin pulled low after boot up

Rajender — Mon, 13 Dec 2021 09:37:20 GMT

Hi Igor,

Thanks for the reply!

We are using uboot : U-Boot 2020.04-5.4.70-2.3.3+g44f5949dd9. We are not able to detect PHY in U-boot, But we are able to detect RTL8211F as per kernel log, we are getting following lines in kernel dmesg log but we don't see any link activity on ethernet port.

RTL8211F Gigabit Ethernet 30be0000.ethernet-1:01: attached PHY driver [RTL8211F Gigabit Ethernet] (mii_bus:phy_addr=30be0000.ethernet-1:01, irq=POLL)

I am attaching U-boot screen shot with this