topic Re: i.MX93 RMII 50MHz Reference Clock Disappears After Linux Boot in i.MX Processors

i.MX93 RMII 50MHz Reference Clock Disappears After Linux Boot

seongkeunjin — Fri, 30 Jan 2026 08:50:09 GMT

I am using i.MX93 with two Ethernet ports configured in RMII mode, where the SoC provides the 50 MHz RMII reference clock.
With the attached DTS, the 50 MHz RMII clock is correctly output during U-Boot, but disappears after Linux boots.
Please analyze the attached DTS and advise:
- The root cause of the RMII clock being disabled in Linux
- Required Linux device-tree changes or driver/clock configuration
- Any known limitations or mandatory settings for SoC-generated RMII clock on i.MX93
I would appreciate guidance on the correct configuration or recommended solution.

Best regards,
David

Re: i.MX93 RMII 50MHz Reference Clock Disappears After Linux Boot

seongkeunjin — Fri, 30 Jan 2026 08:51:30 GMT

The DTS file is here.

Re: i.MX93 RMII 50MHz Reference Clock Disappears After Linux Boot

joanxie — Sat, 31 Jan 2026 06:01:18 GMT

firstly I suggest that you can refer to the attached AN which has very detailed settings and configuration for imx93 RMII mode